CA2422415A1

CA2422415A1 - Multi-phase energy absorbing and impact attenuating modules

Info

Publication number: CA2422415A1
Application number: CA002422415A
Authority: CA
Inventors: Lawrence R. Parisotto
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-03-13
Filing date: 2003-03-07
Publication date: 2003-09-13

Abstract

An improved energy absorbing and impact attenuating module comprising multip le layers of energy absorbing cores, panels or articles fused or bonded together by common facin g sheets or otherwise fixed or positioned adjacent or in juxtaposition to one another to form an integral module each layer comprising honeycomb, foam or other energy absorbing materials. The properti es of the energy absorbing layers are designed and produced with a variation in physical properties such as thickness, density, crush and compressive strength to provide a specified no n- progressive crush sequence of layers or segments of layers and specified compound load (stress ) versus deflection (strain) response upon impact as the layers of the module crush. The successive layers in the crush sequence are positioned preferentially maximally distal to one another in th e module. The module of the present invention is more efficient and effective than energy absorbi ng articles of prior art by incorporating multi-phase energy absorption, designated deceleration and attenuation of the impacting body, and transfer and reflection of impact energy within and between layers or segments of layers of the module. The energy absorbing and impact attenuating respons e of the module can be designed specifically for a wide range of impact energies and variety of applications including an impact-absorbing barrier for racecars, highway barriers, automobile bumper systems, automobile chassis components, interior and door panels, crash and sports helmets, safe ty and protective equipment, protective clothing and the like.

Description

MULTI-PHASE ENERGY ABSORBING AND IMPACT ATTENUATING MODULES
BACKGROUND OF THE INVENTION
Field of the Invention This invention pertains generally to mufti-layer energy absorbing and impact attenuating articles, particularly honeycomb and foam articles with or without facing sheets integrated to the core, that form mufti-layer modules designed to enhance absorption of impact energy and attenuate in a controlled fashion an impacting body by plastically, elastically or viscoelastically deforming, crushing or compressing upon impact thereby reducing potential. injury and damage resulting from an impact.
More specifically, this invention relates to mufti-layered honeycomb, foam, or articles of other energy absorbing materials of similar or varying sizes fused or bonded together by common facing sheets or surfaces, or otherwise fixed or positioned adjacent or in juxtaposition to one another to form an integral energy absorbing and impact attenuating module in which the individual layers are generally designed and manufactured to provide a specified crush sequence within and/or between layers in the module, mufti-phase energy absorbing response and controlled attenuation of an impacting body of low to extreme impact energy. It will be understood that the term honeycomb core also includes modified honeycomb and honeycomb-like structures and that the term foam includes any energy absorbing foam material or reinforced foam. material that has compressive or crush strength including expanded polystyrene, expanded polypropylene, polyurethane, vinyl nitrile, viscoelastic, open-celled, closed cell and metallic foams.
The energy absorbing honeycomb, foam, and articles of other energy absorbing material may be designed to be effective for a single impact only, i.e., plastic deformation, or for multiple impacts, i.e., elastic or viscoelastic deformation, by varying the material ~ztilized.
The cores, panels or articles are positioned relative to one another in the specified configuration of the present invention described herein to load, reflect and transfer an increased or ma~:imized amount of impact energy between and/or within layers or segments of layers in the integral module as it is compressed, crushed or deformed to enhance its energy absorbing characteristics relative to single layer or single density energy absorbing structures. The energy absorbing modules are positioned to intercede in an impact between an impacting body of variable mass and energy with a receiving body, e.g., a racecar colliding with a receiving body such as a concrete barrier, or a head with an energy

2 absorbing liner in a sports or crash helmet, so used to not only absorb the impact energy but also attenuate the impact energy in a controlled and designated fashion, thus producing a specified deceleration response which cushions the impact and minimizes abrupt changes in impact dynamics.
The mufti-phase energy absorbing and impact attenuating modules of the present invention described herein have broad and varied applicability in manufactured articles, for example, in the automotive, motor sports, sports and recreation fields. Several aspects of the present invention are provided to demonstrate the inventiveness, r~velty and utility of the claimed invention. The aspects of the invention described are a mufti-phase energy absorbing and impact attenuating barrier system for use with racecars and automobiles; a mufti-phase energy absorbing and impact attenuating bumper assembly and system for vehicles; a mufti-phase energy absorbing and impact attenuating structure within a vehicle door, chassis structure, or protective sl:ructure for an interior compartment for example, the cockpit surround of an open wheel racecar; and a mufti-phase energy absorbing and impact attenuating component of safety or protective equipment, for example, crash and sports helmets or other protective equipment and clothing. While specified in the context of the aspects and embodiments described herein, the mufti-phase energy absorbing and impact attenuating modules may be advantageously used in any energy absorbingarticles in which the physical damage of and injury to the impacting body, and its occupants if applicable, be F-educed or minimized, regardless of the relative impact energy.
DESCRIPTION OF PRIOR ART
The structural and energy absorbing properties of honeycomb, foam and other energy absorbing structures and articles are well known and have been previously described by those skilled in the art. Energy absorbing articles of prior art typically utilize a single honeycomb or foam layer and are limited by the energy absorbing response characteristic of the single layer.
More efficient energy absorbing responses in these single layer or single density energy absorbing articles are typically achieved by increasing the thickness or altering the density of the article.
In some instances where physical dimensions are constrained, increasing the thickness of the energy absorbing material is not a viable option. Additionally, single density energy absorbing materials represent a compromise to overall energy absorbing capacity being either too soft (i.e., low compressive or crush strength) when kinetic energies are high, or too hard (i.e., high compressive or crush strength) when kinetic

3 energies are low. In either of the latter situations an abrupt change in impact dynamics and spike in deceleration forces which may cause injury and damage occurs when the material perfectly crushes if it is too soft, or before it begins crushing if it is too hard.
Because the kinetic energy of an object in motion is equal to l/2mvz, where m equals the mass of the object and v equals the speed of the object, the energy which is converted to force at and during impact is related to the square of the speed. Thus, as the speed of the object is reduced by half, the energy is reduced by one quarter. Additionally, the distance over which impact energy is absorbed determines the magnitude of the force and deceleration involved; because distance is generally limited in most applications, an energy absorbing article must be as efficient as possible. The time over which the impact energy is absorbed is also a critical factor, generally, the longer the time the lower the forces.
However, single layer energy absorbing articles have only a single response characteristic of the energy absorbing material. For honeycomb, this response generally involves an initial compressive strength followed by a relatively constant crush strength until perfect crushing is approached at which point the honeycomb essentially becomes a solid and the load increases radically with little or no change in deflection. For resilient foam the response is often represented by a stress versus percent strain function exhibiting a curve that steadily increases in slope dependent on the modulus of the foam until all cells have collapsed at which point the foam essentially becomes a solid and the stress on the foam increases radically with little or no change; in percent deflection or strain.
Honeycomb.
Generally, honeycomb is used in structural applications where strength and bending stiffness are required, but with a minimum of weight. One such example is the aerospace industry where honeycomb panels made of aluminum or other materials are used extensively in the manufacture of aircraft. However, honeycomb is not only useful in structural applications where strength and weight are a concern, but also in impac~absorbing applications where strength and weight are a concern. Honeycomb has excellent impact-absorbing properties in its thickness direction because energy from an impact is dispersed throughout the honeycomb matrix. Since the cells of a honeycomb matrix are interconnected, energy from an incident, colliding body is not only absorbed by the cell or cells involved, but also those adjacent to the involved cells by nature of common cell walls.

4 Honeycomb structures and properties are described in terms of their thickness (T) direction, length direction (L), and width direction (W). The core is the central member of the honeycomb structure.
Honeycomb can be manufactured through a variety of processes such as extrusion, injection molding, pressure molding, expansion and corrugation that results in a honeycomb core. The resultant cells of the honeycomb core may be round, rectangular or polygonal in honeycomb-like structures but are commonly produced to be hexagonal in true honeycomb structures.
Modified honeycomb structures comprise honeycomb cells but may be modified in their structure, e.g., containing openings in the cell walls or junctions to modify the compressive properties of the honeycomb core. Honeycomb consisting of hexagonal cells may comprise true hexagonal cells, under-expanded hexagonal cells where the cell diameter in the L direction is greater than the cell diameter in the W direction (L>W), and over-expanded cells where the cell diameter in the W
direction is greater than the cell diameter in the L direction (W>L).
Typically, honeycomb cannot be bent to form contours, though under-expanded and over-expanded honeycomb are capable of moderate contours.
It will be understood that a honeycomb panel is comprised of a honeycomb core and a facing sheet or sheets. A facing sheet is a flat sheet of material fused or bonded to the open ends in the T
direction of the honeycomb or foam core. Honeycomb cores are capable of carrying transverse loads when produced with facing sheets bonded or fused to both. sides of the honeycomb core in the T direction to produce a honeycomb panel that also carries tensile and compressive loads. The bare compressive strength of a honeycomb core is its ultimate compressive strength as measured in pounds (kilograms) per square inch (square centimeter) when loaded in the T
direction. The stabilized compressive strength is the ultimate compressive strength of the honeycomb core when stabilized by a facing sheet bonded or fused to the honeycomb core, i.e., a honeycomb panel, when loaded in the T direction. The stabilized compressive strength is greater than the bare compressive strength for identical honeycomb cores.
It is primarily the compressive strength in the T direction of the honeycomb structure that is utilized for absorbing the energy of an impact. Once the ultimate compressive strength of the honeycomb has been exceeded, it will typically deform plastically or elastically, and crush uniformly, typically at a constant stress level depending on the core material and its density as measured in pounds (kilograms) per cubic foot (cubic metre). This constant stress level is defined as the crush strength expressed in pounds (kilograms) per square inch (square centimeter) and is described as the average crush load per unit cross-sectional area. The energy absorption capacity of honeycomb cores and panels in the T direction are therefore predictable in load versus deflection measurements and can be engineered for specific energy absorption applications. Advantageously, the embodiments of the present invention utilize multiple layers of honeycomb cores, articles or structures with different energy absorbing characteristics to provide for a mufti-phase energy absorbing and impact attenuating response.
As stated previously, honeycomb will initially resist crushing until the bare or stabilized compressive strength is realized, and subsequently crush predictably at a crush energy that is less than the bare or stabilized compressive strength. Honeycomb cores can be caused to crush below the compressive strength through a process called pre-crushing or pre-stressing. It will be understood that the terms pre-crushing and pre-stressing are considered synonymous. Pre-crushing allows the honeycomb core to crush at its crush strength upon impact without having to attain the stabilized or bare compressive strength. Advantageously, the embodiments described herein may utilize both pre-crushed and non pre-crushed honeycomb cores, panels, or articles to provide for a mufti-phase energy absorbing and impact attenuating response.
Honeycomb panels also have shear strength in both the L and W direction that is typically dependent on facing sheet material and facing sheet thickness. Shear strength in the L direction is typically greater than that of the W direction for honeycomb panels. Shear strength is also an important characteristic of energy absorbing and impact attenuating articles as incident collisions may not be orthogonal to the surface of the module, but rather from a variety of incident angles.
Thus, the energy absorbing and impact attenuating module must be capable of being resilient, i.e., having sufficient shear strength, along its L or W direction so as to prevent damage to the energy absorbing capability of the honeycomb panels due to piercing impacts from a incident body.
Advantageously, the embodiments described herein utilize a sufficiently resilient facing sheet, outer shell or protective layer to protect the integrity of mufti-phase energy absorbing and impact attenuating modules.
As stated previously, honeycomb cores, panels, or articles have excellent impact-absorbing properties along their T direction because energy from an impact is absorbed and dispersed throughout cells of the honeycomb. This dispersion of impact energy generally occurs within an individual honeycomb layer (infra-layer transfer) in prior art. However, a transfer of impact energy from layer to layer of a mufti-layer integral module (inter-layer transfer) is important not only for enhancing impact energy absorption but also to prolong the time over which the impact energy is dissipated and attenuate the impact energy in a designated and controlled fashion. The specified configuration of honeycomb energy absorbing layers of the present invention can be utilized to increase the transfer of energy within the energy absorbing modlule by producing a specified load versus deflection response and crush sequence of layers within the module as it crushes. This specified configuration of layers also attenuates the impact energy in a designated and controlled fashion.
Energy absorbing articles utilizing a single honeycomb energy absorbing material layer of consistent configuration, density and structure are not only limited to infra-layer transfer of impact energy, but also provide only a single-phase response to impact energy. That is, the crush strength for the honeycomb energy absorbing material, panel or article, while both predictable and capable of being engineered to certain specifications, is of a single order. Once the energy absorbing material has fully (perfectly) crushed, compressed or collapsed in the T
direction under the compressive load of the impact, the energy absorbing properties of the article have been exhausted and the honeycomb core, panel or article effectively becomes solid causing a significant and abrupt change in impact dynamics. These significant and abrupt changes in impact dynamics can cause 'spikes', i.e., very rapid increases, in deceleration forces that may cause injury or damage.
Advantageously, the mufti-phase energy absorbing and impact attenuating module of the present invention utilizes a plurality of honeycomb, foam or other energy absorbing layers to produce a mufti-phase energy absorbing and impact attenuating response to an impacting body that utilize a compound function of several energy absorbing responses forming an exponential, logarithmic or linear response of the appropriate order to reduce the abrupt changes in impact dynamics.
Honeycomb structures of prior art have been commonly made of materials and adhesives that are classified as rigid and deform plastically, such as aluminum, fiberglass, carbon, NomexTM or even cardboard. Honeycomb structures manufactured from norrelastic materials are incapable of recovering once impacted and crushed. To enhance the energy absorbing capacity of honeycomb manufactured from rigid materials, multiple layers of honeycomb panels fused or bonded by common facing sheets have been utilized, each comprising different energy absorbing properties, e.g., from highest to lowest crush strength or vice versa. These examples of prior art, however, do not produce an enhanced transfer of impact energy nor do they specify a non successive crush or compression sequence or claim an optimum relationship between crush strengths of different panels. Alternatively, single layer modified honeycomb structures have been utilized to enhance energy absorbing capacity. Single layer modified honeycomb structures, while capable of modifying the energy absorbing response, are constrained by the thickness T of the single honeycomb structure.
Those who have described mufti-layer honeycomb impact absorbing systems manufactured from plastic materials include Niemeski (1999, US Patent 6,004,066), who described an impactor for a moveable, deformable barrier simulating the front end of an automobile for the purpose of crash safety evaluation comprising a plurality of energy absorbing impact segments each comprising a plurality of layers of aluminum honeycomb having different crush strength characterized by increasing crush strength of successive layers from the outer impact face.
Eskandrian et al. (1997) also described a mufti-compartment honeycomb material for usf; in a surrogate reusable test vehicle used by the United States Federal Highway Administration in crash tests named Bogie. The multi-layer honeycomb impactors described by Niemeski and Eskandrian et al. are designed to simulate a specific vehicle type in crash tests rather than provide optimum energy absorbing properties.
Those who have described single layer modified honeycomb structures include Bitzer (2001, US
Patent 6,245,408) who described a modified honeycomb structure in which the crush properties are modified and controlled by crush control surfaces that form openings through the cell walls at intersections to provide a reduction in crush strength of the honeycomb cell.
Bitzer claims a wide variety of crush properties for a given honeycomb achieved by varying the size, shape, number and location of the crush control surfaces within the honeycomb in preferred embodiments of aluminum, aluminum alloy or cellulose-based materials.
Due to the relatively inelastic materials utilized in mufti-layer or modified honeycomb structures of prior art, the impact absorbing capabilities of inventions such as those of Niermeski and Bitzer utilizing multiple layers of honeycomb or a modified honeycomb structure are designed to be exhausted after a single, severe impact. Additionally, although multiple layers of honeycomb as described in prior art will provide for a mufti-phase energy absorbing characteristic, no specification g has been provided or claimed in prior art with respect to no~successive crush sequences or how to advantageously integrate the energy absorbing properties of individual layers or increase transfer of energy from the impact throughout the multiple layers of the honeycomb structure to enhance the energy absorption and impact attenuating properties of honeycomb.
Prior art also describes the use of elastomeric materials in energy absorbing applications of honeycomb. Utilizing materials of elastomeric composition in honeycomb may provide resilience for multiple impacts. Utilizing materials of elastomeric composition may also increase the load bearing capability and enhance the article's ability to absorb high or extreme energy impacts.
Utilizing an elastomeric composition that has a moderated or controlled memory for its original morphology and controlled rebound characteristics to resume that shape may both increase the load bearing capability of the article and its ability to absorb and attenuate multiple impacts.
Thermoplastic elastomers (TPE) have been selected in energy absorbing applications due to their exceptional compressive, tensile and tear strength, resistance to puncture, and flexibility at low and high temperatures. Landi et al. (1991, US Patent 5,039,567) have utilized such a material in a honeycomb core for impact absorbing bumpers on an amusement ride.
Honeycomb cores, panels and articles may not have the same physical properties in their T, L, and W directions, that is, they are generally anisotropic. Honeycomb consisting of over-expanded cells produced from thermoplastic elastomers and a fusion-bonding process may result in a flexible honeycomb that is anisotropic. Anisotropic honeycomb may be designed with different attributes in its L, W, and T directions allowing it to absorb energy and impacts from different angles. The impact absorbing properties of anisotropic honeycomb is affected by the physical properties of the honeycomb core, the facing material, cell diameter, thickness of cell wall and the thickness T of the core. Anisotropic honeycomb may also be used to produce contoured panels rather than linear panels and thus are useful in applications where slight contours are required, for example, automobile bumpers. Thus, anisotropic, elastic honeycomb can be engineered to absorb specific loads, to a desired flexibility, to a specific puncture resistance and to a controlled rebound.
Advantageously, utilizing multiple layers of anisotropic, elastic honeycomb in the energy absorbing and impact attenuating honeycomb modules of this invention provides for multiple impact, multi-phase energy absorption and impact attenuation of an incident body in a variety of configurations that are compact and of more effective energy absorbing capacity than prior art.

It is an object of the present invention to achieve a compound, mufti-phase load versus displacement response for mufti-layer honeycomb articles of total thickness T such that the mufti-Iayer article is more efficient in its energy absorbing capacity than a single layer honeycomb of equal thickness T.
Moreover, the time over which the impact energy is absorbed in a mufti-layer foam article can be potentially increased by the preferential positioning of successive layers or segments of layers in the crush sequence positioned maximally distal from one another by increasing the distance in which the stress wave is propagated and reflected within the module.
Foam.
Foam is also well known in energy absorbing applications. Foarn articles consist generally of a vast network of minute three-dimensional cells resembling a honeycomb structure shaped in a pentagonal dodecahedron configuration (twelve five-sided planf;s). Foams may be open celled or closed-cell. Foams may be manufactured from a variety of procf;sses and result in foams that may be either flexible or rigid and are generally isotropic in their energy absorbing capacity. Flexible foams are primarily used in cushioning or shock absorbing applications while rigid polyurethane foams are primarily used as thermal insulators or other similar insulating applications. Expanded polypropylene (EPP), flexible polyurethane (FPF) or expanded polystyrene (EPS) foams are used in impact absorbing functions. Single density expanded polypropylene (El'P), expanded polystyrene (EPS), polyurethane, vinyl nitrite (VN) and other compressible foams are used in sports and crash helmet liners of prior art.
Flexible foam is somewhat similar in structure to honeycomb in that the cells of the foam are made up of two structural parts, cell walls (struts) and open window areas (voids).
The strut and void structure allows air to pass through the foam; when a force is applied the struts and air within the voids are compressed. The elasticity of the struts acts as a shock absorber and allows the foam to recover its shape after compression allowing for use in multiple impact situations. Expanded polypropylene (EPP) foam is capable of absorbing multiple impacts, as are viscoelastic foams such as open-celled polyurethane foams. Other foam energy absorbing materials may be effective only for single impacts. Expanded polystyrene (EPP) absorbs energy by developing micro-fractures throughout its structure and thus is effective only for single impact situations.

It will be understood that a foam energy absorbing layer or article is self defining and a foam panel is comprised of a foam core with a facing sheet or sheets attached to its surface. Foam is typically isotropic in its energy absorbing characteristics thereby absorbing energy in its thickness (T), length (L), or width (W) directions. Foam may be fibre-reinforced or otherwise modified to provide for increased compressive strength in its T direction. A facing sheet is a flat sheet of material fused or bonded to the open ends in the T, L or W direction of the foam core.
While honeycomb crushes at a relatively constant crush strength, generally most resilient foams exhibit a compression force deflection consistent with Hooke's Law, i.e., the further the foam is compressed, the harder the foam pushes back against the compressive force.
Thus, a load (stress) versus displacement (percent strain) function exhibits a curve that steadily increases in slope dependent on the modulus of the foam until all cells have collapsed and the foam essentially becomes a solid and the stiffness of the foam increases radically.
The compressive strength of foam energy absorbing materials is typically measured at 25 percent, 50 percent and 75percent compression (strain, deflection) of the foam material. Foam materials may have a complex compressive strength (load, stress) versus strain function of varying orders that may be in basic terms referred to as approximating an exponentially shaped function of various orders.
Some foams, e.g., CONFOR TM made by E-A-R Specialty Composites, may have a strain ratc-sensitive stiffness characteristic in which the dynamic properties have a significantly greater stiffness at higher strain rates. Energy absorbing articles or structures of a single (or only slightly variable) density of prior art have a compressive strength versus strain function characteristic of the material, while a mufti-layer energy absorbing article may have several compressive strength versus strain functions that may be integrated to form a more efficient compound compressive strength versus strain function. This compound function can be designed to cause a secondary inter-layer transfer of impact energy caused when the compressive strength of a layer at a certain strain is less than the compressive strength of a norrsuccessive layer in the preferential crush sequence.
The inventive concept of the present invention for multiple layers of energy absorbing and impact attenuating articles manufactured of honeycomb cores and panels also applies to foam. However, the stress versus strain function of foam in basic terms is an approximation of a power or exponentially-shaped function rather than a threshold compressive strength followed by relatively constant crush strength as is the case with honeycomb. A compound, mufti-phase stress versus l percent strain response may be achieved for mufti-layer foam articles of total thickness T such that the mufti-layer article is more efficient in its energy absorbing capacity than a single layer foam of equal thickness T.
Moreover, the time over which the impact energy is absorbed in a mufti-layer foam article can be potentially increased by the preferential positioning of successive layers or segments of layers in the crush sequence positioned maximally distal from one another bar increasing the distance in which the stress wave is propagated and reflected within the module. A secondary intra- and inter-layer propagation and transfer of impact energy within the mufti-phase energy absorbing and impact attenuating module can be achieved by ordering the relative connpressive strengths at 25 percent, 50 percent and 75 percent strain of the different foam layers such that segments of individual layers and segments of layers are also positioned maximally distal from their predecessor in the crush sequence.
Advantageously, the aspects and embodiments described herein utilize multiple layers of foam articles or structures of differing physical properties, e.g., thickn.ess, density, compressive and crush strength, to provide for a mufti-phase energy absorbing and impact attenuating response.
Mufti-layer Energy Absorbing Articles.
Literature on the compound energy absorbing properties of mufti-compartment or mufti-layer energy absorbing articles is not common. The inventive concept., embodiments and aspects of the present invention are based on a preferential non-progressive crush sequence of energy absorbing layers in response to the propagation of the stress wave resulting from the impact and transfer and reflection of impact energy between and through interceding layers and segments of layers of greater compressive strength in a mufti-layer energy absorbing and impact attenuating module so as to partially load or compress the interceding layers.
Yasui (2000) indicates that in the case of a three-layer uniformed build-up honeycomb panel subjected to dropped-hammer impact and placed on a backing material of significantly greater compressive strength (for example, concrete), the crushing of thc~ panels occurred in the order of top panel, the bottom panel and middle panel in that order on drop-hammer testing.
After perfect crushing of the top panel, the crushing of the bottom panel occurred from the center portion. After perfect crushing of both the top and bottom panel, the crushing o~f the middle panel occurred from the lower portion of the panel. Additionally, the number of crushing response steps in the load versus displacement data corresponded to the number of honey<;omb layers.
Thus, when mufti-layer energy absorbing honeycomb materials which are backed and supported by a backing material of significantly greater compressive strength are subjected to an innpact, impact energy and forces are transferred through the energy absorbing material and layers such that compression or crushing of the energy absorbing materials against the backing material also occurs. In the applications of the present invention, such a backing surface may be a concrete barrier to which an energy absorbing and impact attenuating module is positioned against in the aspect of a motor sports safety barrier, or the hard, outer liner of a sports or recreational helmet to which the energy absorbing and impact attenuating helmet liner is positioned against.
Yasui found that the energy absorption of the pyramid build-up type (prismatic streamlined) of mufti-layer panels was superior in efficiency and capacity in comparison to the uniform build-up type. Yasui also indicated that mufti-layer panels of the pyramid built-up type accompanied with the uniform build-up type can be expected to provide high performance impact energy absorption.
Pyramid build-up of mufti-layer energy absorbing articles in which the layers of lesser surface area are firstly subjected to the impacting object have demonstrated efficiency in shock absorption applications because the energy and force of impact is distributed over a smaller area causing the initial layer or layers to compress quickly, and then the crushing or compression of the subsequent layers of greater surface area occurs more slowly as the layers with the greater surface area are loaded. Yasui's results indicate that the crush sequence of layers of similar or varying sizes in a mufti-layer honeycomb module are not necessarily progressive from one layer to its adjacent layer, and thus the propagation of a stress wave resulting from impact energy can indeed load layers, be reflected or transferred between layers or segments of layers in a mufti-layer module.
It is an object of the present invention to create a designated non-progressive crush sequence of layers or segments of layers positioned preferentially maximally distal from their predecessor in the crush sequence within the module to maximize the distance the :dress wave is propagated during absorption of impact e~rgy, loading (stressing) of layers of greater compressive strength positioned between successive layers of the crush sequence, and transfer and/or reflection of impact energy between layers or segments of layers of a mufti-layer energy absorbing module to enhance its energy absorbing performance. If impact energy is considered to propagate as a stress wave in an impact attenuating material, then by increasing the distance over which the stress wave is propagated through and reflected at layer boundaries as impact energy is absorbed can potentially increase the time over which the impact energy is absorbed, which enhances the energy absorbing characteristic of the energy absorbing article. if interceding layers of energy absorbing material of sufficiently greater compressive and/or strength are positioned t:o propagate stress waves through to a maximally distal layer, then some impact energy may be absorbed into heat or loading of the interceding layer also enhancing the energy absorbing characteristic of the energy absorbing article.
Advantageously, the mufti-phase energy absorbing and impact attenuating module of this invention provides for an increased transfer of impact energy within the module by utilizing a plurality of honeycomb or foam layers of varying physical properties such as thickness, density, compressive and crush strengths, e.g., five discrete honeycomb panels or foam layers, in a preferred configuration that produces a specified preferential crush sequence of maximally distal layers within the module and loading of layers that intercede between successive distal layers of the crush sequence with impact energy that is transferred and/or reflected within and between layers or segments of layers. By ordering layers within the module according to increasing density, crush strength and/or compressive strengths, and decreasing thickness, and positioning the layers of increasing density, crush strength and/or compressive strengths, and decreasing thickness, maximally distal to its predecessor in the specified crush sequence in the module, a preferential crush sequence of layers is created in the module. Note that successive panels are placed preferentially maximally distal from their predecessor but may also be placed distal or adjacent to their predecessor as required.
The variation in physical properties of layers may also be achieved by varying the structural properties of the individual honeycomb or foam core or panels, c~.g., the material used, core thickness, cell diameter, cell wall thickness, length of cell, presence of facing sheet, facing sheet material and thickness, and pre-crushing of honeycomb panels. Additionally, the successively increasing density, crush and/or compressive strengths in layers positioned adjacent, distal or maximally distal from their predecessor in the module are mathematically related to one another to produce an exponential, power, mufti-phase linear or logarithmic; shaped load versus deflection response of varying orders. Ultimately, the load versus deflection response will determine the deceleration of the incident body that characterizes its attenuation.

Thus, in an exemplary module of the present invention, a first layer of least compressive and/or crush strength and maximum thickness is positioned maximally distal from the impacting object in an exemplary module so as to load and partially compress or crush interceding layers and preferentially partially or fully crush the layer of least compressive and/or crush strength and maximum thickness. A second layer of next greater compressive and/or crush strength and next lesser thickness with respect to the first layer is positioned preferably maximally distal in an exemplary module to the first layer of least compressive and/or crush strength and maximum thickness in the module so as to load and partially compress or crush interceding layers and preferentially partially or fully crush the second layer of next greater compressive and/or crush strength and next lesser thickness. A third layer of next greater compressive and/or crush strength and next lesser thickness with respect to the second layer is positioned preferably maximally distal in an exemplary module to the second layer of next greater compressive andlor crush strength and next thinner thickness so as to load and partially compress or crush interceding layers and preferentially partially or fully crush the third layer of next greater compressive and/or crush strength and next lesser thickness. Generally a minimum of a three layer module of total thickness T
is required for the inventive concept to demonstrate a significant increase in efficiency over a single layer energy absorbing article of similar or equivalent thickness T, though any number of layers greater than one can be used by extension of the inventive concept. For example, in an exemplary 4 layer module, a fourth layer of next greater compressive and/or crush strength and next lesser thickness with respect to the third layer is positioned preferably maximally distal in the module to the third layer of next greater compressive and/or crush strength and next thinner thickness so as to load and partially compress or crush interceding layers and preferentially partially or fully crush the fourth layer of next greater compressive andlor crush strength and next lesser thickness. And in an exemplary five layer module, a fifth layer of next greater compressive and/or crush strength and next lesser thickness with respect to the fourth layer is positioned preferably maximally distal in the module to the fourth layer of next greater compressive and/or crash strength and next thinner thickness so as to load and partially compress or crush interceding layers and preferentially partially or fully crush the fifth layer of next greater compressive and/or crush strength and next lesser thickness. Note that as layers partially or fully compress, some layers may need be positioned adjacent or distal to one another rather than maximally distal to the predecessing layer in the crush sequence. In this manner, a compound load (stress) versus deflection (strain) function is produced, for example in basic terms an exponentially shaped function, in which the resulting load or stress results from the characteristics of the layer being crushed or compressed and the loading and compression of interceding layers.
While in basic terms the compound response may be mufti-phase liner, power, logarithmic or exponentially-shaped, a compound exponentially-shaped load versus deflection response and absorption of impact energy is advantageous because energy absorption and deceleration is relatively low initially in impact dynamics when kinetic energy is high and progressively and exponentially greater as kinetic energy of the impacting object is reduced.
This function is consistent with the relationship of kinetic energy being related to the square of the speed. That is, a mufti-phase exponentially-shaped load (stress) versus deflection (strain) response of an appropriate order to an impacting object not only absorbs impact energy bui:
advantageously attenuates the impact in a manner that cushions the impact by progressively and exponentially decelerating the impacting object more quickly as its kinetic energy is being reduced. It is an object ofthe present invention to describe a mufti-phase response produced by an enf;rgy absorbing article comprising multiple layers of energy absorbing materials of different physical properties such as thickness, density, compressive and crush strengths of total thickness T which is more efficient and effective in absorbing impact energy than a single layer, single density article of equal thickness T. This will allow for enhanced performance from an energy absorbing article of similar or equivalent thickness, or similar or equivalent performance from an energy absorbing article that is thinner or lighter.
Note that while honeycomb generally crushes at constant crush strength regardless of load depending on its physical characteristics such as density and cell size for the bulk of its deflection, resilient foam generally has a stress versus percent strain response of steadily increasing slope as percent strain increases that may vary on static or dynamic compression. If the stress versus strain response is considered in basic terms to be of four discrete segments, i.e., a first segment from 0-25 percent strain, a second segment from 26-50 percent strain, a third segment from 51-75 percent strain, and a fourth segment from 76-100 percent strain, then each layer of a mufti-layer energy absorbing and impact attenuating module could be considered to comprise four compressive or crush segments. Thus, segments of layers may also be positioned according to increasing crush and/or compressive strengths such that segments of layers are positioned preferentially maximally distal from their predecessor in the module and are tnathematica:lly related to one another to produce an exponential, power, mufti-phase linear or logarithmic shaped load versus deflection response of varying orders. For example, in an exemplary three layer modules of the present invention as described above, a first segment of a second layer is positioned maximally distal from a first segment of a first layer and of compressive and/or crush strength such that the stress wave may propagate, load, deflect or transfer energy through the interceding third layer and preferentially crushes before a second segment of the first layer. Likewise, a second segment of the second layer is positioned maximally distal from a second segment of the first layer and of compressive andlor crush strength such that the stress wave may propagate, load, deflect or transfer energy through the interceding third layer and preferentially crushes before a third segment of layer one. The inventive concept is extended to further segments and layers of the module.
Due to the variety of impact energies possible in the aspects of the present invention, e.g., greater than approximately 300 g (300 times the force of gravity) in impact dynamics, the energy absorbing and impact attenuating module of the present invention has several different energy absorbing layers and thus phases of energy absorption and impact attenuation in which the impact absorbing properties are not too hard for low energy impacts nor exhausted or perfectly crushed upon high or extreme impact energies relative to single layer or single density honeycomb or foam articles. The energy absorption and impact attenuation response may be advantageously designed to be synergistic with respect to the energy absorbing characteristics of the impacting body, if applicable, thereby creating a maximum summative response representing energy absorbing components of both the incident body and impacted body. For example, the compressive strength of each of the honeycomb panels in an energy absorbing and impact attenuating barrier for motor sports can be designed to be synergistic with the impact absorbing crumple zones of the impacting racecar (e.g.
wheel and suspension components) producing not only a mufti-phase energy absorbing and impact attenuating response, but also a mufti-phase energy absorbing and impact attenuating response that is synergistic with the energy absorbing and impact attenuating n~esponse of the racecar. Likewise, the compressive strength of each of the foam layers in an energy absorbing and impact attenuating module used in a racecar head rest or cockpit surround can be designed to be synergistic with the impact absorbing characteristics of the helmet that will impact it producing not only a mufti-phase energy absorbing and impact attenuating response, but also a mufti-phase energy absorbing and impact attenuating response that is synergistic with the energy absorbing and impact attenuating response of the impacting helmet.
The more efficient energy absorbing and impact attenuating modules of this invention may be manufactured by a variety of processes and of materials classified as rigid and plastic, e.g., l~
aluminum or aluminum foam, in which only a single impact is required to be accommodated, or elastic, viscoelastic, or elastomeric materials, e.g., thermoplastic elastomers or viscoelastic foams, of moderated or controlled rebound where multiple impacts are required to be accommodated.
Advantageously, the embodiments of the mufti-phase energy absorbing and impact attenuating modules described herein also provide for mufti-phase energy absorption and impact attenuation of multiple impacts with a limited "dead time" when utilizing materials that deform elastically. Due to the unpredictable nature of collisions involving incident bodies such as racecars or automobiles, or in sporting events, it is not inconceivable that an impact with a rnulti-phase energy absorbing and impact attenuating module would be the only impact in the course of an uncontrolled accident, but rather it possible that another collision could impact the same portion of the mufti-phase energy absorbing and impact attenuating module before it be repaired o~r replaced.
Utilizing elastic, elastomeric or viscoelastic materials that return to their original morphology within a minimum dead time, that is the time the mufti-phase energy absorbing and impact attenuating module structures require to return from a crushed, deformed or compressed state to a sufficiently energy absorbing and impact attenuating state and provide a specified percentage of their original multi-phase energy absorbing and impact attenuating properties, allows for accommodation of multiple impacts.
Traffic and Safety Barriers.
In the first aspect of this invention, this invention relates to traffic barriers used to absorb and attenuate the impact energy of racecars colliding with barrier systems that define the limits of race tracks including, but not limited to, oval, tri-oval, speedway, super speedway, temporary street circuits, road racing courses, drag racing or any combination of the former.
The mufti-impact, mufti-phase energy absorbing and impact attenuating barrier system of this invention is installed in intimate association with and in a prescribed alignment with existing concrete barrier systems thereby interacting with incident colliding racecars 'From a multi~hzde of incident angles and in a multitude of orientations to absorb energy and attenuate the impact of the racecar thereby decreasing the peak force of impact in multiples of the force of gravity ~g force) and increasing the time as measured in milliseconds over which the peak g force is exerted thereby reducing injury to the racecar driver and damage to the incident colliding racecar. 'lf'lhese factors are particularly significant in collisions between a racecar and an energy absorbing and impact attenuating barrier 1~
system because the length of time that impact energy is dissipated as measured in milliseconds is an important characteristic of the barrier system.
Automobile racing tracks require a barrier that defines the outer limits of the race track to prevent racecars from leaving the racing surface, and to contain any debris from the normal course of the racing event or racing collisions which occur during the racing event within the confines of the race track. Automobile racing tracks also require a barrier that defines a spectator area physically separate and remote from the racetrack to provide a safe envirorunent for spectators. A necessary and increasingly important characteristic of this type of barrier that has emerged as raeecar speeds have increased is that it must have some degree of energy absorbing and impact attenuating properties to minimize physical damage to racecars and racing drivers upon collision with the barrier.
Historically, a number of devices have been utilized primarily for the purpose of defining the outer limits of the racing surface or track and defining a remote spectator area -devices such as hay bales, dirt beans, wooden and metal railings, concrete abutments, wire fencing or combinations of the above. In particular, steel fencing, such as Armco, and concrete abutments, such as concrete barriers with a rectangular surface parallel to and in a vertical orientation to the racetrack and attached wire containment fencing, serve as barriers commonly utilized in European and North American automobile racing events respectively. Concrete barrier systems have become commonplace in North American racing because they are modular, not dislodged or damaged after an impact with an incident racecar, do not require repair within or between racing events, and have no associated parts that may be dislodged during the collision that cause a danger to other racing vehicles, drivers or spectators.
However, while the latter barrier systems serve well to define the outer limits of the racetrack and contain ordinary or extraordinary racing debris, they do so by providing a fixed, hard surface ('hard wall'), and thus do not have any significant energy absorbing and impact attenuating properties to reduce peak impact forces and assist in preventing serious injury to a raging driver or significant damage to the racecar. The impact absorbing responsibility of such a collision lies solely with the racecar.

A commonplace and economical solution used in road racing applications is to supplement the existing racetrack barrier system, e.g., concrete barriers, metal barriers and beans, with tire barriers consisting of used automobile tires lying horizontally and bundled sevcral tires high in adjoining vertical columns, sometimes with a rigid tube placed in the tire .opening of the vertical column, to provide energy-absorbing characteristics (refer to Federation Internationale de L'Autornobile Standard 8861-2000, FIA Energy Absorbing Inserts for Formula ~ne, Tire Barriers Standard).
These tire barriers are typically used in applications where the racetrack barrier system is at a distance from the racing surface itself such as may be the case in road racing circuits, that is, where a gravel trap or grass field intercedes between the racing surface and racetrack barrier system.
However, tire barriers are not useful in applications where the racing surface and barrier system are immediately adjacent to one another because significant impacts with an incident racecar during the event can dislodge the tire barrier module itself or break the tire bundles causing the dislodged tires or associated hardware from the barrier to be a safety hazard to l:he racing event.
Those skilled in the art have previously described energy absorbing or attenuating elements in a plurality of barrier modules manufactured of a variety of materials such as metal, polymers or rubber to be utilized for absorbing the impact of incident colliding vehicles Yunick (1997, US Patent 5,645,368) described a racetrack consisting of barrier modules including a base mounted on the barrier support surface delineating two crash barrier rings circumscribing the racing surface with the inner ring in a juxtaposed relationship wiah the racing surface. Yunick's invention relates also to racetracks and their constn~ction, more particularly to new vehicle racetracks constructed with novel and improved crash barriers. However, the novel barrier method described by Yunick cannot be integrated easily, if at all, with existing barner systems found at existing racetracks.
Muller (1998, US Patent 5,851,005) described the use of hexagonal metal elements to absorb incident impacts, however the impact-absorbing capabilities of such a device are exhausted after a single severe impact and afford no further impact absorbing properties for collisions that may occur immediately after this first impact. Arthur (1999, US Patent 6,276,667) described the use of cylindrical elements of a rubber or polymer material that may reo:ain their impact-absorbing characteristics after an initial severe impact. Muller and Arthur .have both chosen to align the impact absorbing hexagonal or cylindrical elements such that the long axes are parallel and longitudinal to the vertical surface of the existing barrier rather than orthogonal. Such alignment provides for only limited collapse or compression of the elements as defined by the material, and width of the hexagonal or cylindrical elements. Moreover, longitudinal alignment of similar hexagonal or cylindrical elements does not provide for multiphase energy absorbing or impact attenuating characteristic s.
In the application of an energy absorbing and impact attenuating barrier system for racing or other vehicles, an energy absorbing material must have a controlled rebound characteristic to prevent impact energy from the collision being transferred back to the impacting body.
A controlled rebound property of an energy absorbing and impact attenuating barrier system is critical in automobile racing because incident colliding racecars must have' as much impact energy as possible absorbed and dispersed throughout the honeycomb or foam structure yet have a minimum of rebound to prevent energy from being transferred back to the incident vehicle causing either more energy to be absorbed by the racecar structure or, in the case of a relatively elastic collision, cause the racecar to be propelled back into the race track, possibly into the path of oncoming racing traffic.
More recently, those skilled in the art have considered barriers whereby materials of relatively low density, for example, low, medium or high density foam, have been placed in front of the existing concrete barrier system to provide energy absorbing and impact attenuating characteristics generally known as 'soft wall' barriers. Due to the relatively low density of these materials, however, a significant depth of material is required to attenuate racing vehi<;les, thus decreasing the overall usable surface of the racetrack. Moreover, these materials are generally not resilient and a single impact may exhaust or significantly reduce the energy absorbing; and impact attenuating characteristics of such barriers. In addition, unless a combination of materials of various densities is utilized in the 'soft wall' barrier design, the energy absorbing and impact attenuating properties of such a system are also of a single phase owing to the single density energy-absorbing medium.
Thermoset elastomers (TSE) consisting of cross-linked polymer chains have also been considered for 'soft wall' applications. Safari Associates, Inc. utilize a material called MolecuthaneT"'~ for soft wall applications in automobile racing. While TSE barriers may be designed with suitable energy absorbing and impact attenuating characteristics in their thickness direction, and may provide multi-phase absorption and attenuation due to layers of differing densities, they may cause a 'pocketing' response as described below and are also generally not recyclable as thermoplastic elastomers (TPE) are.
Other 'soft wall' barrier solutions such as sacrificial inertial barriers that utilize frangible barriers containing energy absorbing dispersible mass including sand and water (Pitch, 1999, US Patent

5,957,616) have been described. A single, severe impact with the frangible barrier will not only exhaust or significantly reduce its energy absorbing and impact attenuating capabilities, but also may contaminate the racing surface with the dispersed energy-absorbing material.
However, 'soft wall' barrier solutions may result in a 'snagging" or 'pocketing' characteristic that snags incident cars upon impact when they penetrate the relatively soft materials thereby causing a very fast deceleration of the incident car that in fact may cause significant damage to the driver in the collision of the car with the 'soft wall' due to the; pronounced deceleration forces associated with the 'pocketing' response.
A solution in prior art to the problems of 'soft walls' and 'pocketing' responses is to use an impenetrable outer surface to the barrier system such as high-density polyethylene, guardrails or rectangular metal tubing. The Indy Racing League (IRL) and Indianapolis Motor Speedway (IMS) installed a barrier system on the inside of Turn 4 in 1998 called the Polyethylene Energy Dissipating System (PEDS) utilizing 5-foot long overlapping, high density, polyethylene impact plates with two 16-inch diameter polyethylene cylinders bolted behind the impact plates acting as the energy absorbing medium. However, the high-density polyethylene impact plates are not sufficiently resilient when positioned on the outside of a curve to avoid penetration and subsequent 'snagging' or 'pocketing' by an impacting racecar.
Pitch (1999, US Patent 5,921,702) describes displaceable highway safety barrier system extending along the side of a roadway that includes a number of skid assemblies resting without attachment on a supporting surface adjacent to the roadway. However, such displaceable guardrail barriers require many mounting and interface members and significant space requirements. Pitch (2000, US Patent

6,010,275) also describes a compression guardrail including a rail extending longitudinally along a roadway with a plurality of fixed support posts spaced behind thf: rail and resilient compressible energy absorbing means mounted between the rail and the posts. However, in both systems described by Fitch, the barrier itself is a continuous, strong, impenetrable surface and, while bendable, as such is not easily displaceable or compressible, therefore not providing an energy absorbing or impact attenuating response as efficient as possible.
The Indy Racing League (IRL) and Indianapolis Motor Speedway (IMS) have developed a barrier system in conjunction with the Midwest Roadside Safety Facility at the University of Nebraska -Lincoln called the SAFER (Steel and Foam Energy Reduction) barrier that was installed on the outside of turns at IMS in the spring of 2002. The barrier consists of four rectangular structural steel tubes welded together forming sections, each section joined to the next by heavy steel internal splines. Bundles of 2-inch thick polystyrene sheets are placed between the structural steel tube barrier and the existing concrete barrier. The polystyrene bloclts comprise several layers and may utilize differing densities or thicknesses, however an integrated response and crush sequence of maximally distal layers is not specified.
An efficient racing safety barrier should resist breaking, avoid snagging of incident vehicles or racecars, bend or displace to absorb a significant amount of impact energy, and redirect the incident vehicle or racecar without bouncing it back across the traffic stream. Thus, an object of an improved energy absorbing and impact attenuating barrier is to utilize the .advantages of a 'soft wall' system, i.e., effective energy absorption due to the compression of an energy absorbing medium or media, with the advantages of a 'hard wall' barrier, i.e., without the inherent detrimental 'pocketing' response, yet provide for improved energy absorption by providing a more bendable, displaceable and compressible barrier system as compared to axed, continuous, 'hard wall' systems such the IRL
SAFER system.
Accordingly, several objects and advantages of the mufti-impact, mufti-phase, energy absorbing and impact attenuating barrier system described herein are:
(a) the energy-absorbing characteristics of the barrier system are not exhausted after a single impact such as is the case in energy absorbing barrier systems utilizing a light density crushable material such as foam (Nelson, 1999,US Patent 5,860,762) or metal (Mul:ler, 1998, US
Patent 5,851,005) that do not provide energy absorbing or impact attenuating characteristics for a secondary incident following the primary impact prior to repair being affected to said energy absorbing barrier system.

(b) the mufti-layered panels of the barrier system provide for a specific mufti-phase energy absorbing and impact attenuating response that inherently absorbs an increased amount of impact energy due to the transfer of impact energy between layers within the module as compared to the energy absorbing capabilities of prior art.
(c) the barrier system is relatively compact and integrated easily with the existing concrete barrier system as compared to other 'soft wall' designs so as to be practical and economical.
(d) the impact-absorbing and attenuating barrier system elements are fixed with a minimum of hardware to the existing concrete barrier system in a manner that prevents elements from being dislodged or damaged such that they or debris from them may be dangerous to other drivers, vehicles or spectators.
(e) there are no dispersible elements of the impact absorbing and attenuating barrier system that will interfere with the racing circuit or cause consequence to the race after impact and consequent rupture of the energy absorbing barrier such as is the case with frangible barriers.
(f) the energy-absorbing characteristics of an energy absorbing and impact attenuating barrier system are mufti-phase due to different shapes, configurations, a.nd physical dimensions of energy absorbing components rather than providing a linear or single phase attenuation due to the use of a single material of consistent density, shape, configuration or physical dimension.
(g) the energy absorbing and attenuating characteristics, becausf; they are designed to be variable and mufti-phase, may be 'tuned' or engineered to certain specifications to be complementary and synergistic with the impact absorbing characteristics of the racecar or vehicle in use.
{h) the energy-absorbing and attenuating characteristics are designed such that in relative terms, in comparison to the existing concrete ('hard") barrier system, the :impact absorbing and attenuating barrier system is:
~ relatively 'hard' for crash energy below approximately 5 to 10 times the multiple of the force of gravity (5-10g) and the racing vehicle primarily absorbs the bulk of the impact, thus not sacrificing absorption characteristics of the wall for inconsequential collisions, nor having 'soft' portions of the wall that an incident racecar could interact with (e.g., puncture, get impeded by, get caught up with) in highly oblique collisions. This may be achieved by means of a sufficiently resilient facing sheet or protective apron positioned in intimate contact and in a prescribed fashion external to the honeycomb module and facing incident colliding bodies.
~ relatively 'arm', yet progressively more energy absorbing and impact attenuating for crash energy between approximately 10 to 40 times the multiple of the force of gravity ( 10-40g), and the racing vehicle and said impact absorbing and attenuating barrier system share in a synergistic manner the impact energy of the crash, ~ relatively 'soft' for crash energy above approximately 40 times the multiple of the force of gravity (40g) and the impact absorbing and attenuating barrier system absorbs a shared but increasingly larger portion of the impact energy of the crash. In this capacity, a mufti-phase energy absorbing and impact attenuating response, e.g., logarithmic or f;xponential, tuned to the incident body, e.g., an open wheel racecar, becomes increasingly significant.
(i) the energy absorbing and attenuating elements of the impact absorbing and attenuating components can be easily reconfigured and 'tuned' for different applications (e.g., open wheel racecars, closed wheel racecars) without involving an altered process of manufacture.
(j) that, where it is understood that the impact absorbing and attenuating harrier system is not required to be installed adjacent to the existing concrete barrier system around the racetrack in its entirety, that contoured end-piece components be designed and manufactured to define the beginning and end of the energy absorbing and impact attenuating barrier system.
{k) the energy absorbing and attenuating barrier manufacturing process is well known to those skilled in the art and can be made of a materials familiar to those associated with the racing and tire industry thereby offering both an economical and practical advantage.
Further objects and advantages of the mufti-impact, mufti-phase energy absorbing and impact attenuating barrier system described herein are to provide an impact absorbing and attenuating barrier system in conjunction with existing concrete barrier systems that are inert to environmental forces, require a minimum of maintenance, and maintain a surface for other previously defined functions of the concrete barrier system, e.g. advertising.
Still further objects and advantages will become apparent from review and consideration of the ensuing description and drawings.
Automobile Bumper Assembly and System.
In the second aspect of this invention, this invention relates to a mufti-phase energy absorbing and impact attenuating core material for automobile bumper assemblies in which said mufti-phase energy absorbing and impact attenuating core material for an automobile bumper assembly is an integrated component of an automobile bumper system comprising a compound energy absorbing and impact attenuating response involving the bumper assembly and vehicle energy absorbing crumple zones of the chassis or unit body.
It is well known that automobiles may sustain front and rear impacts of varying energies during routine operation. The use of front and rear automobile bumpers in automobiles in North America was mandated in 1925. Automobile bumpers generally serve two fianctions, one, to provide the esthetic function of extending downward the front and back bodywork of the vehicle with continuity to its overall shape, and, two, to perform the mechanical fun<;tion of absorbing impacts of a variety of energies that the vehicle may sustain.
Those skilled in the art have devised methods involving metal bumpers, metal bumpers augmented by hydraulic or mechanical dampers, tubes, profiles or honeycomb structures.
According to Glance (US Patent 5799991, 1998) most contemporary automobile bumper systems consist of three basic components, a bumper beam, a bumper absorber, and a cover or fascia. The bumper beam is often metal, the bumper absorber is commonly a shock absorbing device or a polypropylene foam block, and the fascia is typically molded from a urethane plastic. Recently, thermoplastic elastomers (TPE) and thermoplastic polyolefins (TPO) have been used to manufacture molded, deformable, glass mat reinforced bumpers. Tusim et al. (2001, US Patent 6,213,540) describes an energy absorbing article of extruded thermoplastic foam that exhibits anisotropic compressive strength for use in light weight plastic automobile energy absorbing units (EAU).

More recently, hybrid steel/thermoplastic TPO bumpers have been described for lighter bumpers resilient to small impacts. The use of elastomers in molded bumpers and bumper fascias provides great design flexibility, lighter weight, improved resistance to impacts and corrosion, and the ability to recycle old or damaged bumpers.
The required energy absorption capacity of an autormobile bumper directly relates to the weight of the vehicle, i.e., the heavier the vehicle, the higher the levels of energy absorbing capacity are required. Bumpers for light cars often utilize a metal or composite fiber reinforced beam fixed to the vehicle frame with a molded foam polypropylene energy absorbing block mounted between the beam and the fascia cover. Bumpers for heavy cars often utilize a metal or composite fiber reinforced beam mounted on hydraulic shock absorbing devices.
While many of these automobile bumper assemblies satisfy the requirements 2 miles per hour (4 kilometres per hour) and 5 miles per hour (8 kilometres per hour) impact tests, they have limitations. The energy absorbing and impact attenuating properties of existing bumper assemblies may not be sufficient for high impact energies thereby causing a. large portion of the impact energy to be transferred to the vehicle structure and thus the occupants of the vehicle.
Occupant injuries can be reduced if a greater amount of impact .energy is isolated from the vehicle chassis or unit body structure, and if the impact energy is absorbed by the bumper assembly and vehicle chassis or unit body structure in an integrated manner to prevent abrupt changes in impact dynamics. Impact energy is not generally absorbed in an integrated fashion by the bumper assembly and the energy absorbing crumple zones of the vehicle chassis or unit body structure with which the bumper assembly is in association with in prior art. This causes an abrupt change in impact dynamics in vehicles with bumper assemblies of prior art and causes a transfer of a significant amount of impact energy in an abrupt manner to the vehicle chassis or unit body structure potentially to the detriment of the driver and passengers.
Additionally, due to the primarily single-phase energy absorption and impact attenuating characteristics of energy absorbing cores of prior art, the only way to increase the impact absorbing capacity involves increasing the dimensions and/or masses of the energy absorbing devices.

Advantageously, the mufti-phase energy absorbing and impact attenuating module of the present invention can be utilized as the absorber or core material of an automobile bumper assembly with the thickness direction of the honeycomb and/or foam module aligned generally parallel and longitudinal to the direction of front and rear impacts, i.e., parallel and longitudinal to the length of the vehicle. The individual panels or layers and overall energy absorbing response of the module may be tuned to the weight of the vehicle providing for a cost advantage by means of the same configuration of core material being used for light and heavy vehicles, but with a variation in structure creating appropriate energy absorbing and impact attenuating properties specific to the vehicle. The module may be contoured to the shape of the bumper to serve both esthetic and impact absorbing functions. The honeycomb and/or foam modules of this invention when used as the absorber or core material for automobile bumpers may be fused or bonded on the one side to an outer foam component associated with the bumper fascia to provide resilience for multiple inconsequential impacts, and on the other side, to the inner beam component of the bumper, or be aligned in intimate contact with the energy absorbing crumple zone structure of the vehicle itself.
The load versus deflection response of the mufti-phase energy absorbing and impact attenuating module of the present invention module is designed with respect to weight of the vehicle and overall compressive and crush strengths of the front or rear crumple zones of the vehicle chassis or unit body or other vehicle structures with which it is in intimate association with. The maximum transfer of impact energy between layers within the mul ti-phase energy absorbing and impact attenuating module will isolate a greater amount of impact enerl;y from the vehicle structure and thus the occupants of the vehicle, thereby potentially reducing morbidity or mortality of the vehicle occupants. The mufti-impact capabilities of the mufti-phase energy absorbing and impact attenuating module utilized as a core material for bumper assemblies also provides for energy absorption of secondary impacts, for example, a rear impact from another vehicle may cause the impacted vehicle to careen out of control and collide with another body in the same area impacted by the primary impact.
Further advantages have been described in the other aspects of this invention.
Still further objects and advantages will become apparent from review and consideration of the ensuing descriptions and drawings.

2~
Energy Absorbing Vehicle Structure.
In the third aspect of the present invention, this invention relates to a mufti-phase energy absorbing and impact attenuating module for a vehicle door, or other vehicle, cha:>sis, cabin or cockpit energy absorbing structure.
Automobile doors are constructed in a well-known manner typically comprising an inner and outer door panel. A decorative door trim panel is usually affixed to the inner door panel.
It is well known that automobiles may sustain side or other imp;~cts of ~aarying energies that intrude upon the cabin during their routine operation. Those knowledgeable in the art have employed various means to absorb the impact energy of a side collision with an automobile to protect the occupants from injury. Metal beams have been positioned in vehicle doors to protect occupants from side collisions but offered little energy absorbing characteristics. hoam materials, egg crate or cone shaped structures have been described whereby these articles are positioned between the inner and outer door panels to provide energy absorbing capabilities. :Elowever, the space between the inner and outer door panel is typically small and varying in width and is intruded upon by various mechanical components making it difficult for low density, single-phase energy absorbing structures to be effective for higher impact energies involved in automobile collisions. More recently, side impact air bags have been utilized to protect vehicle occupants from side impacts, and while effective, are relatively expensive both in initial installment and repair.
Honeycomb has been described by those skilled in the art as an energy absorbing material for vehicle doors and other vehicle structures. Saathoff ( 1994, US Patent 5,306,066) whose assignee was the Ford Motor Company described a honeycomb shaped energy absorbing structure for absorbing energy from a side collision type impact of the door vehicle.
Saathoff listed advantages of his invention as being able to be tuned to meet side collision type impact requirements, having the honeycomb shaped energy absorbing structure precrushed to provide lower crush strength, and being light weight and low cost compared to conventional foam material and cone shaped structures. However, Saathoff claimed only a single layer honeycomb structure made of precrushed aluminum, thus of single phase, plastic response.
Wielinga (2000, US Patent 6,117,520) whose assigalee was AB Volvo (SE) described a honeycomb block useful as an impact force-absorbing element in a door of a vehicle comprising three sections of cardboard honeycomb elements characterized in that the cell size of each honeycomb element section decreases from a large size in one section to a smaller si:ae in the neighboring section and an even smaller size in the third section facing inward with respect to the passenger compartment of the vehicle. While Wielinga claimed a mufti-layered honeycomb block that provides for a gradually hardened impact, he does not claim an embodiment that provides for a tuneable energy absorbing response, a preferred crush sequence or a means for maximizing the transfer of impact energy within the honeycomb block as described for the a mufti-phase energy absorbing and impact attenuating module for a vehicle door of this invention. While claiming a progressively smaller cell size from the outer to inner sections of the honeycomb block, there is no consideration or relation of compressive or crush strengths of individual layers claimed by '~Vielenga, nor of an elastic response.
Advantageously, the mufti-phase energy absorbing and impact attenuating module for a vehicle door or other vehicle chassis or cabin structure of the present invention provides improved energy absorption due to the tunable and specified mufti-phase response in a limited space described in the previous aspects of this invention. The load versus deflection re sponse of the module is designed to be complementary or synergistic with respect to the overall corr.~pressive strength of the door or other vehicle chassis and cabin structures that it is in intimate association with. In this application, the controlled and moderated rebound characteristics of the honeycomb module are not critical as in the farst aspect of this invention, i.e., some energy from the collision may be transferred back to the impacting body. The multiphase energy absorbing and impact attenuating honeycomb module of this invention may also be utilized similarly in other vehicle chassis or cabin structures such as the firewall, dashboard, pillars, rear crumple zone and passenger safety cell..
Head injury of drivers and occupants is also a problem in vehicles and racecars. Road-going vehicles generally have energy absorbing foam materials positioned to intercede in an impact between the head or other body parts of the driver or occupant and a vehicle chassis structure, for example, dashboards and cabin pillars. Cockpit surrounds and head rests comprised of energy absorbent foams are generally utilized in racecars as well to attempt to miniz~ize head injury. These safety features are typically limited in the thickness of energy absorbing material due to design constraints. With such limitations, the more efficient the capacity of the energy absorbing honeycomb and foam materials, the more effective the energy absorbing capability will be given the same thickness of material. Advantageously, the more efficient mufti-layer energy absorbing and impact attenuating modules of the present invention provide enhanced performance without increasing the thickness of energy absorbing material.
Further advantages have been described in the other aspects of this invention.
Still further objects and advantages will become apparent from review and consideration of the ensuing descriptions and drawings.
Crash, Sports and Recreational Helmets.
In yet another aspect of this invention, this invention relates to a mufti-impact, mufti-phase energy absorbing and impact attenuating component of protective or safety equipment, e.g., liners for protective clothing, articles, and equipment, and sports and crash helmets.
Protective clothing, articles and equipment such as shin pads, gloves, and shoulder pads are used in contact sports such as football and hockey to protect the wearer from injury. Sports and Brash helmets are used by persons engaging in sporting, recreational and work activities in which they are exposed to a risk of head injury. Protective clothing, articles, equipment and helmets. of prior art generally comprise a hard outer shell that serves to diffuse, distribute and absorb impact energy, an inner liner that further absorbs the energy of the impact and cushions (i.e., attenuates) the impact sufficiently to protect the wearer from injury, comfort or sizing pads, and a retention system that maintains the protective device appropriately on the wearer's body.
Improvements on existing sports and crash helmet designs may be made by utilizing the more efficient mufti-phase energy absorbing and impact attenuating nodules of the present invention described herein to offer improved performance, for example improved energy absorbing capacity with the same or similar physical dimensions of prior art, or similar or equivalent performance as compared to prior art with lighter and/or thinner energy absorbing liners.
Additionally, the inner liner and hard outer shell may be treated as integral components of a mufti-layer energy absorbing module to further enhance its energy absorbing capability.
Crash Helmets.
Drivers and passengers of motorcycles, cars and other vehicles involved in racing events are exposed to a high risk of head injury and are generally required to wear a crash helmet meeting specified standards.

Generally, a crash helmet requires a strong, shatterproof outer shell and an inner liner that dissipates energy and cushions the head from sharp impacts to the shell, thereby protecting the head and brain from linear and rotational impact energy. The outer shell is substantially spheroidal in shape and typically consists of an injectior~molded thermoplastic or pressure-molded thermoset reinforced with fibres. In prior art, the inner foam liner is commonly polystyrene, but may be polyurethane foam. The crash helmet absorbs impact energy when the outer shell bends and the underlying foam deforms. The foam inner liner can generally compress by approximately 90 percent during an impact, thus provided cushioning of a blow to the head. However, if the maximum strain exceeds the approximate 90 percent compression, then the foam becomes effectively solid and linear and rotational impact energy will be transmitted to the head.
Typically, the energy absorbing capability of the foam inner lirner of crash helmets of prior art is limited by having single density foam of limited thickness. As tlhe single layer foam liner approaches complete crushing due to the impact, it no longer absorbs impact energy causing an abrupt change in impact absorption dynamics, causing transfer of impact energy to the head thereby potentially causing morbidity and mortality. Additionally, the energy absorbing response of the inner liner and outer shell of crash helmets of prior are not well integrated, that is, the compressive strength and energy absorbing characteristics of the foam liner and shell do not form an integrated, compound response which minimizes abrupt changes between phases of impact dynamics. In the case of a crash helmet, thickness and density of the shell and liner must be limited as increased helmet mass and size can add to angular inertia of the head increasing risk of neck injury and helmet roll off Advantageously, the mufti-phase energy absorbing and impact attenuating module of the present invention can be utilized to form a mufti-layer crash helmet liner which provides improved energy absorption with the same total thickness and weight compared t~o single layer foam liners, or thinner, lighter liners with similar or equivalent performance. In particular, an exemplary embodiment of this invention in the aspect of a crash helmet involves multiple layers of foam of differing densities positioned intimately adjacent to one another in the inner liner, with the inner liner in intimate association with the outer shell, the outer shell being consistent with prior art or comprising an inner and outer facing sheet of substantially a spheroidal shape with a honeycomb core integrated between the facing sheets.

The outer shell is manufactured by a variety of processes, for example injection or pressure molding of a thermoplastic or thermoset material. Advantageously the c~~mpressive strengths of the inner liner foam layers and outer shell of the crash helmet of this inventive concept are designed relative to one another such that the impact is firstly diffused, dispersed and absorbed partially by the outer shell, then by a successive crush sequence of the foam layers of differing physical properties such as density and thickness of the inner liner while minimizing changes in impact dynamics between layers and phases of impact absorption by formang an integrated, compound, exponentially-shaped stress (load) versus strain (deflection) response. The layers are positioned such that successive layers according to density, thickness and/or compressive strengths are positioned preferentially maximally distal, but also distal or adjacent where required, from one another in the crush sequence.
Sports/Recreational Helmets.
Head injury remains a significant cause of morbidity and mortality in sporting, recreational and work activities.
Sports and recreational helmets generally fall into one of three categories.
1. Helmets generally comprising a hard outer shell of a thermoplastic material, an energy-absorbing inner liner of expanded polystyrene (EPS) or expanded polypropylene (EPP) or similar material, and comfort or sizing pads of flexible foam.
2. Helmets comprising an EPS, EPP or similar layer and comfort or sizing pads of flexible foam with no outer shell.
3. Helmets comprising an EPS, EPP or similar layer and comfort or sizing pads of flexible foam with a thin outer microshell of thermoplastic material.
EPS liners are generally rigid, inelastic and permanently deform on impact and thus are useful only for single impacts. EPP liners are sufficiently elastic to accommodate multiple impacts. Flexible and viscoelastic foams are also generally sufficiently elastic to accommodate multiple impacts Mendoza (United States patent Application 20020023291) describes a safety helmet constructed of layers of polyurethane, monoprene gel, polyethylene and either :polycarbonate or polypropylene. An alternate embodiment is described in which multiple layers of impact absorbing inner layers of two, three or more different densities may be utilized. However, there is no description or claims relating to crush sequence, positioning or relative thickness of layers, or an integrated, compound response.

Moore, III (United States Patent 6,453,476) describes a protective helmet which preferably has a hard outer shell and an energy absorbing liner made of low resilience or slow-recovery foam which is compression rate sensitive. Moore claims a liner with a first, second and third portion of viscoelastic polymeric foam, each portion of which has a different stiffness.
Moore claims the first, second and third foams as positioned adjacent to one another in different portions of the helmet rather than layering the foams however. While this configuration allows for three different compressive strengths in three different portions of the helmet liner, the different portions are not layered and do not create a mufti-phase response in a specific portion of the helmet liner.
Halstead, et al. (Unites States Patent 6,434,755) describes a helmet with a one-piece first shock attenuating member positioned adjacent to and substantially in contact with portions of the inner surface of the shell, and a plurality of second shock attenuating members positioned adjacent to portions of the first shock attenuating member and adjacent to and substantially in contact with portions of the inner surface of the shell. Each second shock attenuating member has a second thickness and second density, the second density of which is greater than the first thickness and the second compression deflection being less than the first compression deflection. The second shock attenuating members, being thicker and of less compression deflection than the first shock attenuating member, firstly compress on impact by the head, compressing until the thickness of the first shock attenuating member. However, the first shock attenuating member being preferably constructed of expanded polypropylene (EPP) does not substantially compress and the second shock attenuating members do not further contribute significantly to the energy absorption of the impact.
Thus, while the response of the helmet liner described by Halstead, et al. is mufti-phase, a number of layers greater than two is not claimed, the layers are positioned adjacent to one another rather than built up on one another, compression of the layers being successive does not cause a secondary absorption of impact energy by loading energy absorbing layers positioned between successive layers of the crush sequence, and an optimal compound responsf; is not claimed in which absorption of impact energy is relatively low initially in impact dynamics when kinetic energy is high and progressively greater as kinetic energy of the impacting object is reduced.
Ewing, et al. (United States Patent Application 20020184699, United States Patent 6,425,141 ) described a helmet with a rigid outer shell and three energy-absorbing layers made of two types of open-celled polyurethane foams. The first layer adjacent to the rigid shell and inner-most layer are a CONFOR TM CF-40 yellow foam while the middle layer is a CONFOR TM CF-47 green foam, the middle layer of which is of greater stiffness than the first and imler-most layers. Swing claims at least three energy absorbing layers positioned with respect to one another such that a layer of low dynamic impedance is adjacent to layer of high dynamic impedance, thus comprising alternating layers of energy absorbing materials having different dynamic i~npedances.
Swing describes the multiple layering of materials having different stiffnesses as causing a reflection of propagating stress waves through the materials, ultimately absorbing larger amounts of energy than the same materials not layered with alternating stiffness could absorb. Swing does not describe or claim the loading of, or transfer of energy through, or maximizing the distance of stress wave propagation by layers positioned between successive layers of the crush sequen<;e positioned maximally distal from one another as a secondary energy absorption characteristic enhancing the energy absorbing response. Swing claims alternating layers of high and low impedance rather than successive layers in the crush sequence positioned preferably maximally distal to one another.
Swing does not claim a different thickness for each layer related to its density or comprf;ssivc strength thereby causing a compound exponentially- or logarithmic-shaped compound response of varying orders. Thus, while Swing describes a mufti-phase response with a secondary energy absorption characteristic his claims do not optimize this response.
Additionally, none of the inventions of prior art have considered or claimed the use of thin, pliable facing sheets at the common boundary surface where a layer of thickness, density and compression strength is positioned adjacent to another layer of the same or differing thickness, density and compression strength to further distribute and dissipate impact energy from one layer to another.
Inventions of prior art also do not consider the compressive strength of the hard, outer liner as an integral component of a mufti-layer energy absorbing system thereby not minimizing the abrupt change in impact dynamics that may occur as energy is transferred from the outer shell to the inner liner or vice versa.
Further advantages have been described in the other aspects of this invention.
The above discussed and many other features, objects and advantages of the present invention will be better understood by reference to the following detailed description and accompanying drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Multi-phase Energy Absorbing and Impact Attenuating Traffic and Safety Barriers.
Referring now to the ensuing diagrams, a mufti-phase energy absorbing and impact attenuating module 10 is shown generally in FIG. 1 wherein said module is a component of an impact-absorbing barrier for racecars or highway barriers comprising several panels, each panel of which comprises a honeycomb or foam core with or without a facing sheet or sheets, each core of which comprises a plurality of honeycomb or foam cells. An exemplary five-layer honeycomb module is shown generally in FIG. 2, FIG. 3 and FIG. 4 wherein said module is a component of an impact-absorbing barrier for racecars or highway barriers. The exemplary five-layer honeycomb module comprises honeycomb panels 1 l, 12, 13, 14, 15 and facing sheets 31, 32, 33, 34, 35. The honeycomb module is described as a uniform build-up type in which the panels are of the same length and width. It will be understood that the modules of the present invention may also be of the pyramid build up type in which the panel or panels facing the incident body are of a smaller length and width than the back panels facing the receiving body producing a pyramidal build up of panels in the module.
An exemplary honeycomb core is shown generally at 12 in FIG. 5. The honeycomb has a length (L), a width (W) and a thickness (T). It will be understood that t:he same convention of physical dimensions applies to foam core structures or articles. It will be also understood that the exemplary honeycomb 12 is one of multiple honeycomb, modified honeycomb or honeycomb-like cores or foam cores or articles in the mufti-phase energy absorbing and impact attenuating module 10 positioned to intercede in an impact between an incident body of variable mass and energy colliding with a receiving body of variable mass and energy so used to not only absorb the impact energy of the incident body but also attenuate it in a controlled and specified fashion.
It will be further understood that the honeycomb core may be comprised of true honeycomb cells, honeycomb-like cells, over-expanded or under-expanded cells, or modified honeycomb cells and that the honeycomb or foam core may be manufactured of a variety of materials generally classified as rigid, elastic, viscoelastic, plastic, polymeric, elastomeric or fibre reinforced elastomeric by processes including molding, extrusion, expansion and corrugation. Where mufti-impact energy absorbing and impact attenuating modules are desired, it will be understood that elastic, viscoelastic or elastomeric materials will be utilized. While an exemplary module of five honeycomb, modified honeycomb or honeycomb-like panels is described, any number of honeycomb, modified honeycomb, honeycomb-like or foam cores, panels or articles greater than one may be used in the exemplary embodiment.
Several exemplary honeycomb cells 21, 22, 23, 24, 25 are shown in FIG. 6 with cell diameter (CD), cell wall thickness (CWT), and cell length (CL) identified. It will be understood that cells 21, 22, 23, 24, 25 may represent true honeycomb cells, honeycomb-like cells, over-expanded or under-expanded cells, or modified honeycomb cells and a:re repeated numerous times throughout each honeycomb, modified honeycomb or honeycomb-like panel. However, the cell type will be consistent in each individual honeycomb, modified honeycomb or honeycomb-like panel, and the density consistent in each foam core panel.
It will be understood that in general terms foam structures and articles have isotropic energy absorbing properties, though cross-linked polymer foams may have relatively superior energy absorption capacity in directions other than the T direction. Thus, while the exemplary module described comprises multiple layers of honeycomb panels, it will be understood that foam layers or articles may also be utilized in one or more layers of the mufti-phase energy absorbing and impact attenuating modules of the present invention.
Facing sheets 3 l, 32 are shown generally in FIG. 7 as fused, bonded or otherwise fixed to the exemplary honeycomb core 12. The exemplary honeycomb panel 13 is generally considered to be comprised of honeycomb core 12 and facing sheets 31, 32. It will be understood that facing sheets 31, 32 are fused, bonded or otherwise fixed to adjoining honeycomb 11 and honeycomb 13 to form multiple layers of honeycomb panels in the mufti-impact, mufti-phase energy absorbing and impact attenuating module 10. Honeycomb 1 l, which is directed towards impacting bodies, may or may not have a facing sheet fused or bonded to its outermost surface impacted firstly by an incident body, and is shown generally in FIG.1 as not having a facing shE:et fused or bonded to its innermost surface. Honeycomb I 1 may also be replaced by a foam core of cross-linked polymer construction.
Referring again to FIG. 3 and FIG. 4, the facing sheet 33 is fused, bonded or otherwise fixed to adjoining honeycomb 13 and honeycomb 14, facing sheet 34 is fused, bonded or otherwise fixed to adjoining honeycomb 14 and honeycomb 15, facing sheet 35 is fused, bonded or otherwise fixed to honeycomb 15 towards the receiving body thus forming multiple: layers of honeycomb panels in the mufti-phase energy absorbing and impact attenuating module la. While impact energy is dispersed from cell to cell in the honeycomb or foam matrix through cells with adjoining cell walls, the presence of facing sheets serves to further dissipate the impact load in two ways, one by further dissipating the impact energy along the front facing sheet facing the impact to non-impacted cells, and two, by further dissipating impact energy along the back facing sheet and to cells in the adjacent layer once the affected cells in the layer have fully compressed under the impact.
The whole honeycomb module 10 is generally constrained by a containment structure at the front, back, top, bottom and either sides of the honeycomb module to prevent the honeycomb or foam cores, panels or articles from being significantly displaced or crashed, compressed or deformed in a direction non-parallel with the T direction. In some instances, the containment of the honeycomb module 10 will be structures other than the specified containment structure that the honeycomb module is in intimate association with, e.g., the bottom being the road, the back being the existing concrete barrier, the sides being adjoining honeycomb modules and the front and top being a protective apron in the aspect of the present invention described for use as a mufti-phase energy absorbing and impact attenuating barrier system for use with racecars and automobiles.
Each honeycomb panel 11, 12, 13, 14, 15 has specified crush, bare and stabilized compressive strengths based on the honeycomb core material, cell diameter (CD) of honeycomb cores 1 l, 12, 13, 14, 15, cell wall thickness (CWT) of honeycomb cores 11, 12, 13, 14, 15, cell length (CL) of honeycomb cores 11, 12, 13, 14, 15, and facing sheet 31, 32, 33., 34, 35 material and thickness. It will be understood that anisotropic foam cores or articles also have specified compressive and crush strengths based on the type and density of the core material.
In FIG. 8, an exemplary relative load versus deflection response graph is depicted representing the uniform and plastic or elastic deformation of an exemplary noirprecrushed honeycomb panel when loaded. The bare compressive strength 51 is shown. The crush strength 52 of the exemplary honeycomb is also indicated and is less than the bare compressive strength 51.
Note that when the honeycomb or foam core has perfectly crushed, i.e., it has maximally crushed, compressed or deformed (the deflection approaches the thickness T), it effectively becomes solid and no further significant deflection can occur to absorb impact energy. It is vitally important that energy absorbing structures do not perfectly compress before the impact energy of a collision is significantly reduced because a significant amount of the impact energy can be transferred back to the incident body in an abrupt manner adversely affecting the impact absorbing dynamics of the energy absorbing and impact attenuating system. The use of mufti-layer energy absorbing modules with progressively increasing crush strength will reduce the likelihood of perfect crushing of the whole module and thus provide for a gradually increasing attenuation and more effectively absorb the impact energy of a collision.
In FIG. 9, an exemplary relative load versus deflection graph is depicted representing the uniform and plastic or elastic deformation of an exemplary precrushed honeycomb when loaded. Crush strength 57 is shown. Note that there is no bare compressive load peak required when the exemplary honeycomb is in the precrushed state before it deforms. Once again, when deflection approaches the thickness T, the crush strength rises dramatically and abruptly as the energy absorbing material effectively becomes a solid.
The exemplary mufti-phase energy absorbing and impact attenuating module 10 is generally shown in FIG. l, FIG. 2, FIG. 3 and FIG. 4 as comprising multiple layers of linear honeycomb panels. The layers may also be slightly contoured to accommodate the curvature of the receiving body, e.g., concrete barriers positioned in corners of the racetrack. The number of layers of honeycomb or foam cores, panels or articles of the modules of this inventiomnay be any number greater than one, but must conform to a specified crush sequence based on positie~n of the core, panel or article within the module, the relative and absolute bare, stabilized or crush strengths, and the state of the core, panel or article being either precrushed or non-precrushed. The exemplary mufti-phase energy absorbing and impact attenuating module 10 is produced wherein honeycomb panels 11, 12, 13, 14, 15 are positioned in a specific configuration according to relative crush, bare and stabilized compressive strengths as well as precrushed or norr~precrushed states such that in the preferred embodiment the honeycomb panels will sequentially crush upon. impact: in the order of 1 l, 15, 12, 14, 13 to maximize transfer of impact energy between layers within the exemplary mufti-phase energy absorbing and impact attenuating module 10. That is, in the crush sequence specified above in an exemplary honeycomb module in the preferred embodiment comprising five honeycomb panels 1 l, 12, 13, 14, 15, impact energy will be firstly absorbed by the crushing of the honeycomb panel 11 least resistant to the load and subsequently be transferred internally through the other layers of the honeycomb module to the maximally distal norrcmshed honeycomb panel. In the preferred embodiment, after honeycomb panel 11 is fully compressed, honeycomb panel 15 will be next least resistant to the impact load as it is the notrcrushed honeycomb panel maximally distal from honeycomb panel 11. By placing honeycomb panels 12, 13, 14 in a non-precrushed state and of greater compressive or crush strength between the honeycomb panel 11 first fully crushed and the successive honeycomb panel 15 in the crush sequence according to relative bare, stabilized or crush strengths in the preferred embodiment, further energy from the impact can be absorbed by applying loads from transferred impact energy through the non-precrushed panels 12, 13, 14, thereby providing for a secondary energy absorption capability by causing some impact energy to be absorbed in the partial loading or pre-crushing of honeycomb panels 12, 13, 14. Advantageously then, impact energy transferred from honeycomb panel to succe;~sive adjacent, distal or maximally distal honeycomb panel in the crush sequence in the preferred elnbodirnent is also dissipated by utilizing the transferred energy to load and partially pre-crush the successive honeycomb panels in the crush sequence. Note that the crush sequence of layers to achieve this secondary energy absorption capability may be a variable, e.g. 1 l, 15, 13, 14, 12, lbut that it does not simply involve successive layers as is the case in a crush sequence of layers 1 l, 12, 13, 14, 15, in that order. Note also that an alternate embodiment in which layer 11 is positioned adjacent the concrete barrier, layer 12 is positioned to face incident traffic, layer 13 is positioned adjacent on the inside (towards the race track) of layer 1 l, layer 14 is positioned adjacent on the outside (towards the concrete barrier) of layer 12, with layer 15 being the middle layer may further optimize the energy absorbing capacity of the mufti-phase energy absorbing and impact attenuating module 10 by maximizing the distance of propagation of the stress wave of impact energy.
In an exemplary embodiment, honeycomb panel 11 of the exemplary honeycomb module 10 least resistant to impact energy is positioned to face incident collidin~; bodies and is firstly impacted by an incident body. Honeycomb panel 11 need not have a facing sheet on the side of the honeycomb core facing the incident colliding objects. Instead, a protective structure, i.e., an apron 55, of metal, plastic or other material may intercede between the honeycomb module 10, specifically honeycomb panel 1 l, and the incident colliding object. In an alternative embodiment, honeycomb panel 11 may have a facing sheet fused, bonded or othea-wise fixed to the side of the honeycomb core facing the incident colliding objects, also serving as a protective structure i:or the honeycomb module. In a third embodiment of this aspect, honeycomb panel 11 ma y have both a facing sheet fused, bonded or otherwise fixed to the side of the honeycomb core facing the :incident colliding objects, and a protective structure of metal, plastic or other such material that intercedes between the honeycomb module 10, specifically honeycomb panel 11, and the incident colliding object to serve as a more substantial protective structure for the honeycomb module. Note that the combination of said protective structure and/or facing sheet must be sufficiently elastic to allow for the exemplary energy absorbing module 10 to react in its designed fashion.

4(1 Referring again to the exemplary embodiment of the exemplary honeycomb module 10 in FIG. 1, FIG. 2, FIG. 3, and FIG. 4 depicting an exemplary mufti-phase energy absorbing and impact attenuating module comprised of five linear honeycomb panels, and the relative load versus deflection graph in FIG. I l, honeycomb panel 11 is in a precrushed state and has a crush strength CS I 1 less than that of honeycomb panel 15 located maximally distal from honeycomb panel 11.
Honeycomb panel 15 is in a precrushed state and has crush strength CS15 greater than CS1 I, but less than that of honeycomb panels 12, 13, and 14. Honeycomb panel I 5 is located maximally distal from honeycomb panel 11. After high or extreme impact energy of greater than CS 11, affected cells of honeycomb panel 11 will plastically or elastically deform and crush until the honeycomb core 11 is fully crushed and compressed. Once fully crushed, the affected cells of honeycomb panel 11 demonstrate no further deflection effectively becoming solid and are in a dead response time such that the energy from the impact is preferentially transferred through the honeycomb module from honeycomb panel 11 to honeycomb panel 15. After receiving sufficient impact energy of greater than CS15, cells of honeycomb panel 15 will plastically or elastically deform and crush until fully crushed or compressed. Once fully crushed, the affected cells of honeycomb panel 15 demonstrate no further deflection effectively becoming solid and are in a dead response time such that the energy from the impact is preferentially transferred through the honeycomb module from honeycomb panel 15 to honeycomb panel I2. Honeycomb panel I2 is in a non precrushed state and has a crush strength CS 12 greater than C S 1 S, but less than that of honeycomb panel 14 located maximally distal from honeycomb panel 12 allowing for the fact that honeycomb panels I l and 15 have plastically deformed, crushed fully, and are in a dead response time.
Cells of honeycomb panel 12 will have been partially loaded and in a partially loaded or precrushed state subsequent to the transfer of impact energy from honeycomb panel 11 to honeycomb panel 15. After receiving sufficient impact energy of greater than stabilized campressive strength SCS
12, cells of honeycomb panel 12 will plastically or elastically deform and crush until fully crushed and compressed. Once fully crushed, the affected cells of honeycomb panel 12 demonstrate no further deflection effectively becoming solid and are in a dead response time such that the energy from the impact is preferentially transferred through the honeycomb module from honeycomb panel 12 to honeycomb panel 14. Honeycomb panel 14 is in a non precrushed state and has a crush strength CS 14 greater than CS 12, but less than that of honeycomb panel 13. Honeycomb panel 14 will be in a partially loaded or precrushed state subsequent to loading from impact energy transferred from honeycomb panel 11 to honeycomb panel 15, and honeycomb panel 15 to honeycomb panel 12.
After receiving sufficient impact energy of greater than stabilized compressive strength SCS14, cells of honeycomb panel 14 will plastically or elastically deform and crush until fully crushed or compressed. Once fully crushed, the affected cells of honeycomb panel 14 demonstrates no further deflection effectively becoming solid and are in a dead response time such that the energy from the impact is preferentially transferred through the honeycomb module from honeycomb panel 14 to honeycomb panel 13. Honeycomb panel 13 is in a nomprecrushed state and has crush strength greater than CS 14, but less than the crush strength of the backing material with which it is in intimate association with, e.g., a concrete barrier of crush strength CSCo in the embodiment described for use as a mufti-phase energy absorbing and impact attenuating barrier system for use with racecars and automobiles. After receiving sufficient impact energy of grf;ater than stabilized compressive strength SCS13, cells of honeycomb panel 13 will plastically or elastically deform and crush until fully crushed and compressed. Once fully crushed, the affected cells of honeycomb panel 13 demonstrate no further deflection effectively becoming solid and are in a dead response time and the maximum energy absorbing and impact attenuating properties of the honeycomb module have been realized. If elastic materials have been utilized, the honeycomb module as a whole is then in a dead time mode for a short duration of time until the cores, panels or articles recover their original shape and size. Note that this exemplary description is for illustrative purposes of the concept the present invention and that the relative crush and compressive strengths, precrushed or non-precrushed states, and crush sequence of panels within the module may be altered and thus tuned specifically to an application.
Generally, in the exemplary embodiment, the core thickness T 1 l and cell length of honeycomb panel 11 CL 11 is greater than that of honeycomb panel 15, the core thickness T 15 and cell length of honeycomb panel 15 CL15 is greater than that of honeycomb panel 12, the core thickness T12 and cell length of honeycomb panel 12 CL 12 is greater than that of honeycomb panel 14, and the core thickness T 14 and cell length of honeycomb panel 14 CL 14 is greater than that of honeycomb panel 13 resulting in an approximation of an exponential shaped response as depicted in FIG. 11. Note that by altering the relative thickness of the cores of honeycomb. panels, e.g., T11<T15<T12<T14<T15, different load versus deflection responses may be achieved, e.g., an approximation of a logarithmic-shaped response can be achiever as depicted in FIG. 13. The load versus deflection response depicted in FIG. 11 will decelerate the incident object relatively slowly at first, then progressively more quickly as the impact energy is absorbed and reduced due to the collision of the incident body with the first layer or layers of the module.
Such a response will provide controlled, tunable attenuation and more gradual absorption or cushioning response to the incident body.
Generally, in the exemplary embodiment, the cell diameter CD 11 of honeycomb panel 11 is greater than the cell diameter CD 15 of honeycomb panel 15, the cell diameter CD 15 of honeycomb panel 15 is greater than the cell diameter CD 12 of honeycomb panel 12, the cell diameter CD 12 of honeycomb panel 12 is greater than the cell diameter CD I4 of honeycomb panel 14, and the cell diameter CD 14 of honeycomb panel 14 is greater than the cell diameter CD 13 of honeycomb panel 13. Note that by altering the relative cell diameters of the cells of the honeycomb panels different responses may be achieved. Additionally, in the exemplary embodiment, the cell wall thickness CWTl 1 of honeycomb panel 11 is less than the cell wall thicknc;ss CW'T15 of honeycomb panel 15, the cell wall thickness CWT15 of honeycomb panel 15 is less than the cell wall thickness CWT12 of honeycomb panel 12, the cell wall thickness CWT 12 of honeycomb panel 12 is less than the cell wall thickness CWTI4 of honeycomb panel 14, and the cell wall thickness CWT14 of honeycomb panel 14 is less than the cell wall thickness CWT13 of honeycomb panel 13.
Note that by altering the relative thickness of the cell walls of the cells of honeycomb panels, different responses may be achieved.
Generally then, in the exemplary embodiment, the successive crush sequence of the honeycomb panels in the exemplary honeycomb module upon impact is honeycomb panel 11, honeycomb panel 15, honeycomb panel I2, honeycomb panel I4, and finally honeycomb panel 13.
FIG. 11 demonstrates the individual relative load versus deflection resp~~nse for the exemplary honeycomb module 10 comprising five layers of honeycomb panels relative to one another and superimposed on the same horizontal axis in the order of successive crush sequence. FIG. 12 demonstrates an approximate exponential-shaped relative load versus deflection response graph for the exemplary honeycomb module 10 considering that the transferred impact energy from one honeycomb panel to another will also serve to load the successive non-precrushed honeycomb panels superimposed on the same horizontal axis in the order of successive crush sequence.
FIG. 13 demonstrates an approximate logarithmic-shaped relative load versus deflection response graph for the exemplary honeycomb module 10 considering that the transferred impact energy from an individual honeycomb panel will also serve to load the successive norrprecrushed honeycomb panel superimposed on the same horizontal axis in the order of successive crush sequence. FIG. 13 demonstrates an approximate exponentially-shaped relative load versus deflection response graph for the exemplary honeycomb module 10 achieved by varying core thickness, cell diameter and cell wall thickness of layers in the module considering that the transfverred impact energy from an individual honeycomb panel will also serve to load the successive non precrushed honeycomb panel superimposed on the same horizontal axis in the order of successive crush sequence. Note that the load versus deflection response of FIG. 13 will quickly decelerate the incident object upon impact with the first layer or layers of the module and then decelerate it more slowly as the impact energy is absorbed and reduced.
FIG. 1 l, FIG. 12, and FIG. 13 demonstrate that the resultant relative load versus deflection curve and thus deceleration response to the incident body for the exemplary honeycomb module 10 can thus be tuned by nature of the core thickness, successive crush and compressive strengths, and crush sequence of the honeycomb panels of the honeycomb module. In some instances, an approximation of a logarithmic-shaped response may be most appropriate for a specific application, while in others an exponential or mufti-phase linear response may be most appropriate. The relative crush strengths, bare and stabilized compressive strengths of the exemplary honeycomb panels may be modified by cell length, cell diameter, cell wall thickness for a given honeycomb core material or by material and density of a foam core. The absolute compressive and crush strengths are designed with respect to expected impact energies and energy absorbing properties of the incident body. In all aspects of the present invention though the resultant load versus deflection response and thus deceleration response is designed to attenuate the impact of either the incident body., receiving body or both. For example, in the aspect of the present invention wherein said mufti-phase energy absorbing and impact attenuating modules are an impact absorbing barrier for racecars, the racecar (incident body) must be decelerated upon impact with the barrier (receiving body) in such a manner so as to minimize damage and injury. This may require an exponential-shaped deceleration versus distance response in which the racecar is initially decelerated relatively slowly while at high speed in the initial phase of the impact, and more quickly decelerated in later phases of the impact after some impact energy has been absorbed.
FIG. 14 illustrates an exemplary mufti-impact, mufti-phase energy absorbing and impact attenuating module in the preferred embodiment wherein said module is a mufti-phase energy absorbing and impact attenuating barrier for use with racecars and automobiles capable of decelerating on impact a racing or other vehicle of very high speed over an extended period of time as measured in milliseconds at a significantly reduced multiple of the force of gravity (g-force) as compared to existing concrete barriers thereby reducing the primary, secondary or tertiary impact gforce per unit millisecond. The barrier system is relatively compact and integrated easily by quick release fasteners 58 at 57 with the existing concrete barrier 51 as compared to other 'soft wall' designs so as to be practical and economical. The barrier system elements are fixed with a minimum of hardware 58 to the existing concrete barrier system 51 in a manner that prevents elements from being dislodged or damaged such that they or debris from them :may be dangerous to other drivers, vehicles or spectators. A protective apron 55 maintains the mufti-impact, mufti-phase energy absorbing and impact attenuating module 10 in intimate association and in a prescribed alignment with the existing concrete barrier 10, such that the "T" direction of the module is orthogonal to the vertical surface of the existing concrete barrier, and also prevents lateral, vertical or horizontal displacement of module I0. The protective apron is substantially a reverse c-type configuration and is fixed and integrated with adjacent outer wall components in an overlapping fashion accounting for rotation or direction of racecars on the racetrack, consists of a smooth, hard outer surface of appropriate longitudinal strength that will not bind significantly with a rotating race tire, and has an easement 56 along its inferior portion to assist with clearing track debris.
Upon impact by an incident racecar or vehicle, the incident body will firstly impact the protective apron 55 causing the impacted area to plastically or elastically deform inwardly towards the module 10. The impacted area of the protective apron will be displaced into the adjacent layer 11 of the module 10. The module 10 will then behave as previously described herein to absorb the energy of the impact and attenuate the racecar or vehicle such that it decelerates in a prescribed fashion.
The mufti-phase energy absorbing and impact attenuating module 10 is designed to be sufficiently resilient to accommodate multiple impacts, and if damaged, is designed to be replaced in short period of time as defined by 'yellow flag' caution periods during a racing event.
Mufti-phase Energy Absorbing and Impact Attenuating Vehicle Bumper System.
Referring now to FIG. 15, FIG. 16 and FIG. 17, an automobile bumper assembly is shown generally at 61. It is known that automobile bumper assemblies of prior aht consist of a bumper beam 62, core 63 and fascia 64 and that the bumper core 63 is primarily responsible for providing energy absorption from incident bodies. The bumper beam 62 is often metal, the bumper core or absorber 63 is commonly a shock absorbing device or a polypropylene foam block, and the fascia 64 is typically molded from a urethane plastic.
The required energy absorption capacity of an automobile bumper assembly 61 directly relates to the weight of the vehicle. While many of automobile bumper systems satisfy 2 miles per hour (4 kilometres per hour) and 5 miles per hour (8 kilometres per hour) impact tests, they have limitations. The energy absorbing and impact attenuating properties of existing bumper assemblies may not be sufficient for high impact energies thereby causing a, large portion of the impact energy to be transferred to the vehicle structure and thus the occupants of the vehicle. The only way to increase the impact absorbing capacity of the bumper assembly involves increasing the dimensions, density and masses of the energy absorbing devices.
Advantageously, the mufti-phase energy absorbing and impact attenuating module 10 of this invention can be utilized as the core of an automobile bumper assembly with the thickness direction of the honeycomb and/or foam layers aligned generally parallel and longitudinal to the direction of front and rear impacts, i.e., paralle.l and longitudinal to the length of the vehicle. The mufti-phase energy absorbing and impact attenuating module 10 is contoured to the shape of the bumper assembly 61 to serve both esthetic and impact absorbing functions. Referring to FIG. 17, the multi-phase energy absorbing and impact attenuating modules of the present invention when used as the core 10 for an automobile bumper assembly 61 may be fused or bonded on the one side to an outer foam component 63 associated with the bumper fascia 64 to provide resilience for multiple inconsequential impacts, and on the other side, to the inner beam 62 of the bumper assembly, or be aligned in intimate contact with the energy absorbing crumple zone structure of the vehicle chassis or unit body itself 68.
The load (stress) versus deflection (strain) response of the mufti-phase energy absorbing and impact attenuating module 10 is designed with respect to the weight of the vehicle and overall compressive and crush strengths of the front or rear crumple zones 68 of the vehicle or other vehicle structures with which it is in intimate association with to form an energy absorbing vehicle bumper system comprising an integrated response. In an exemplary embodiment of the present invention in which the mufti-phase energy absorbing and impact attenuating module 10 is positioned in intimate association with a portion of the energy absorbing crumple zone structure 68 of the vehicle chassis or unit body designed specifically to accommodate the mufti-phase energy absorbing and impact attenuating module 10 of the bumper assembly 61, the compressive and crush strength of the bumper fascia 64 is least, the foam core 63 is of greater compressive and crush strength, the layers of the mufti-phase energy absorbing and impact attenuating module 10 positioned in an exemplary manner maximally distal from their predecessor in the crush sequence have increasing compressive and crush strength in the order of layers 1 I, 15, 12, 14, 13, with the layer 13 of greatest corrq~ressive and crush strength of the mufti-phase energy absorbing and impact attenuating module I O being less than the initial compressive strength of the energy absorbing emmple zone structure of the vehicle chassis or unit body 68. In the exemplary embodiment, layer 11 is positioned nearest the energy absorbing crumple zone structure 68 of the vehicle chassis or unit body, layer 15 positioned adjacent to the foam core 63, layer 12 positioned adjacent layer I 1 facing the foam core 63, layer 14 positioned adjacent layer 15 facing the energy absorbing crump:Le zone structure 68 of the vehicle chassis or unit body, and layer I3 positioned in the middle. In the exemplary embodiment, layer 11 is the thickest, layer 15 next thickest, layer 12 next thickest, layer 14 next thickest and layer 13 least thick. In the exemplary embodiment, layer I 1 has the least density and compressive strength, layer 15 next greatest density and compressive strength, layer 12 next: greatest density and compressive strength, layer 14 next greatest density and compressive strength and layer 13 the greatest density and compressive strength.
In another exemplary embodiment, the metal bumper beam 62 is included and is positioned to intercede between the mufti-phase energy absorbing and impact attenuating module 10 and the energy absorbing crumple zone structure of the vehicle chassis or unit body 68 so used to further disperse and distribute impact energy not absorbed by the bumper of the present invention to the energy absorbing crumple zone structure of the vehicle chassis or unit body 68. The metal bumper beam 62 is designed with appropriate shear strength and stiffness to function as a facing sheet which preferentially deforms after the energy absorbing capability of the bumper assembly 61 of the present invention has crushed significantly prior to and concurrent with the transfer of energy to the energy absorbing crumple zone structure of the vehicle chassis or unit body 68 to further absorb impact energy.
Thus, in a front or rear impact with a vehicle having the bumper assembly and system of the present invention the impact dynamics arc such that the bumper fascia 64 will firstly be impacted. As the fascia 64 is fully or partially compressed or Brushed, impact energy will be transferred to the foam core 63 interceding between the module 10 and the fascia 64. As the foam core 63 fully or partially compresses or crushes, impact energy will be transferred to the multi-phase energy absorbing and impact attenuating module 10, which will advantageously provide enhanced energy absorption by means of the crush sequence of layers positioned preferably maximally distal to their successor in the crush sequence. That is, impact energy and forces Load the mufti-phase energy absorbing and impact attenuating module 10 such that the layer least resistive to the impact energy and forces will compress firstly. Thus, although the stress wave of impact energy will propagate through, load and partially compress interceding layers 15, 14, 13 and 12, layer 11. maximally distal to the impact will preferentially partially or fully crush. Layer 15 next least resistive to the impact energy and force located maximally distal from layer 11 will compress partially or fully next preferentially causing propagation of the stress wave of impact energy to travel a maximum amount and load and partially compress interceding layers 12, 13 and 14. Subsequently, the stress wave of impact energy will propagate to the next least resistive layer 12 positioned maximally distal from layer 15 so as to fully or partially crush it and load and partially crush interceding layers 14 and 13. Subsequently, the stress wave of impact energy will propagate to the next least resistive layer 14 positioned maximally distal from layer 12 so as to fully or partially crush it and load and partially crush interceding layer 13, which will partially or fully crush lastly.
As the mufti-phase energy absorbing and impact attenuating module 1Q is partially or fully compressed or crushed, impact energy will be transferred to the energy absorbing crumple zone structure of the vehicle chassis or unit body 68 if the mufti-phase energy absorbing and impact attenuating module 10 is in intimate contact with the energy absorbing crumple zone structure of the vehicle chassis or unit body 68, or bumper beam 62, if included, which will fully or partially crush or deform serving to further absorb or distribute impact energy. The bumper beam 62, if included, will compress or deform the energy absorbing crumple zone structure of the vehicle chassis or unit body 68.
The compound response of each of the components of the vehicle bumper system of the present invention axe designed to form a compound exponentially-shaped response of an order of which the preferential crush sequence serves to attenuate the impact energy and minimize abrupt changes in impact dynamics. An exemplary simplified compound exponentially-shaped response is shown in FIG. 18.

Mufti-phase Energy Absorbing and Impact Attenuating Vehicle Safety Structures.
Vehicle safety structures such as vehicle cabin interior padding (for example dashboard, steering wheel and cabin pillar padding) and energy absorbing units in door panels serve to reduce injury during road and racing vehicle operation and collisions.
Door Panels.
Refernng now to FIG. 19 and FIG. 20, a vehicle door 71 is depicted illustrating exemplary multi-phase energy absorbing and impact attenuating modules 10 wherein said modules are for use within a vehicle door or other vehicle chassis structure. The outer door panel 71, inner door panel 72 and interior trim panel 73 are shown. In a side collision with the vehicle, the incident body will firstly impact the outer door panel 71 having a compressive and crush strength causing it to plastically deform inwardly towards the driver or passenger of the vehicle. Subsequently, the inner door panel 72 having compressive and crush strength will be impacted causing it to plastically deform inwardly towards the driver or passenger of the vehicle. In an exemplary embodiment of the present invention, the mufti-phase energy absorbing and impact attenuating module 10 is positioned between the inner door panel 72 and interior trim panel 73 to intercede in an impact of sufficient energy such that the outer door panel 71 and inner door panel 72 are sufficiently displaced to impact the driver or occupant 74.
The compressive and crush strengths and overall response of the mufti-phase energy absorbing and impact attenuating modules 10 are designed in relation to the compressive and crush strengths of the inner and outer door panels. Thus, in a side impact with a vehicle having the mufti-phase energy absorbing and impact attenuating modules 10 positioned in association with the inner door panel 72 and interior trim panel 73 of the present invention, the impact dynamics are such that the outer door panel 71 will firstly be impacted. If the outer door panel 71 is displaced sufficiently to impact the inner door panel 72, impact energy will be transferred to the inner door panel 72. If the impact energy is sufficient to cause displacement of the inner door panel 72 to impact the driver or occupant 74, impact energy will be absorbed by the mufti-phase; energy absorbing and impact attenuating module 10, which will advantageously provide enhanced energy absorption by means of the crush sequence of layers positioned preferably maximally distal to their successor in the crush sequence. That is, impact energy and forces load the mufti-phase energy absorbing and impact attenuating module 10 such that the layer least resistive to the impact energy and forces will compress firstly. Thus, although the stress wave of impact energy will propagate through, load and partially compress interceding layers 15, 14, 13 and 12, layer 11 maximally distal to the impact and adjacent the driver or passenger 74 will preferentially partially or fully crush. Layer 1 S next least resistive to the impact energy and force located maximally distal from layer 11 will compress partially or fully next preferentially causing propagation of the stress wave of impact energy to travel a maximum amount and load and partially compress interceding layers 12, 13 and 14.
Subsequently, the stress wave of impact energy will propagate to the next least resistive layer 12 positioned maximally distal from layer 15 so as to fully or partially crush it and load and partially crush interceding layers 14 and 13. Subsequently, the stress wave of impact energy will propagate to the next least resistive layer 14 positioned maximally distal from layer 12 so as to fully or partially crush it and load and partially crush interceding layer 13, which will partially or fully crush lastly.
As the mufti-phase energy absorbing and impact attenuating module 10 is partially or fully compressed or crushed, impact energy will be absorbed so as to reduce injury to the driver or occupant 74. In the exemplary embodiment, the greatest crush and compressive strengths of the mufti-phase energy absorbing and impact attenuating module 10 is less than the compressive or crush strengths of the outer door panel 71 and inner door panel 72. In the exemplary embodiment, layer 11 is the thickest, layer 15 next thickest, layer 12 next thickest, layer 14 next thickest and layer 13 least thick. In the exemplary embodiment, layer 11 has the least density and compressive strength, layer 15 next greatest density and compressive strength, layer 12 next greatest density and compressive strength, layer 14 next greatest density and compressive strength and layer 13 the greatest density and compressive strength.
The compound response of each of the components of the of the present invention are designed to form a compound exponentially-shaped response of an order of which the preferential crush sequence serves to attenuate the impact energy and minimize abrupt changes in impact dynamics.
An exemplary simplified compound exponentially-shaped response is shown in FIG. xx.
Racecar Headrests and Cockpit Surrounds.
Racing vehicles also utilize energy absorbing structures to reduce injury during racing vehicle operation and collisions. In 1996, in an effort to reduce driver injury, the Federation Internationale d'Automobile {FIA) implemented improvements far driver safety including foam padding around the sides and rear of the cockpit opening. In side and rear impacts this foam padded head rest and cockpit surround serve to restrain the head, provide controlled deceleration and prevent head displacement and rotation that could potentially damage the neck. Head rests and cockpit surrounds are now used in many racecars to reduce the likelihood and extent of head injury.
FIG. 21 depicts the cockpit surround 120 and head rest 109 of prior art for an open wheel racecar.
According to specifications for Championship Auto Racing Teams (CART) racecars, the area behind the driver's helmet 80 must be constructed to minimize the effects of neck and/or head injuries in case of impact. The head rest I09, exclusive of padding, is designed to deflect not more than 2.0 inches rearward when a force of 200 pounds is applied. Including the seat back and continuing upward, the surface facing the helmet I25 must be continuous and without gaps.
Contours must not prevent the torso I 1 l and neck/head 1 I2 from moving as a single unit during impact. Under no circumstances shall sharp or protruding objects which could contact the helmet 98 be allowed as a part of the headrest 109 or cackpit surround 120 nor shall such objects be positioned forward of a vertical projection of this surface. The head rest 109 and cockpit surround 120 shall be located as close as practical to the helmet 80 when the driver's head 112 is in the normal operating position and surfaces shall be designed to reduce point loading upon contact with the helmet and should be designed in conjunction with the seat back 108 to allow acceleration of the thorax, spine and head together as a unit. Padding of high hysteresis foam 121 of the following minimum dimensions must be fitted in the areas of most probable helmet contact to minimize injury in case of impact:
Thickness - 2.0 inches minimum.
Height - extend from the base of the driver helmet with the driver seated in a normal driving position to within 6.5 inches of the top of the main rollover hoop.
Width - at least 7.0 inches wide at 10.00 inches from the top of the main rollover hoop. Whenever possible the contact area shall be perpendicular to the chassis reference plane. Foam must be covered to prevent environmental degradation.
FIG. 22 depicts the mufti-phase energy absorbing and impact attenuating module 10 of the present invention are used in head rest 109 and cockpit surround 120 in place of a single foam layer 121 of prior art. An exemplary five layer mufti-phase energy absorbing and impact attenuating module 10 is shown of same total thickness, e.g., 2 inches, as the single layer foam 121 of the head rest 109 and cockpit surround 120 of prior art and made generally of layers of energy absoxbing materials such as elastic foam, viscoelastic foam, and honeycomb. Two embodiments are depicted.

In FIG. 22A, an embodiment is depicted that protects the driver from an intrusive impact, for example, a racecar impacting the driver's racecar perpendicular to the driver's capsule. The layers of energy absorbing materials are positioned such that the Layer 125 with the least compressive and/or crush strength is closest to the helmet 98 of the driver, the layer 126 of next greatest compressive and/or crush strength is adjacent to the chassis or monocoque of the racecar, the layer 127 of next greatest compressive andlor crush strength is positioned adjacent layer 125 towards the chassis or monocoque of the racecar, the Layer 128 of next greatest compressive and/or crush strength is positioned adjacent layer 126 towards the driver, and the layer 129 of next greatest compressive and/or crush strength is positioned in the middle of the five layer module. In the exemplary embodiment, layer 129 is of greatest density, layer 128 next densest, layer 127 next dense, layer 126 next dense and layer 125 least dense of the layers. On an intrusive impact in which the monocoque or chassis structure 130 of the car intrudes into the driver capsule, impact energy displaces the racecar structure 130 towards and contacting the driver, compressing the mufti-phase energy absorbing and imp act attenuating module 10 as it does so. Impact energy and forces load the mufti-phase energy absorbing and impact attenuating module 10 such that the layer least resistive to the impact energy and forces will compress partially or fully frstly. Thus, although the stress wave of impact energy will propagate through, load and partially compress interceding layers 126, 128, 129 and 127, layer 125 maximally distal to the impact will prefE;rentially partially or fully crush.
Layer 126 next least resistive to the impact energy and force located maximally distal from layer 125 will compress partially or fully next preferentially causing propagation of the stress wave of impact energy to travel a maximum amount and load and partially compress interceding layers 127, 129 and 128. Subsequently, the stress wave of impact energy will propagate to the next least resistive layer 127 positioned maximally distal from layer 126 so as to fully or partially crush it and load and partially crush interceding layers 128 and 129. Subsequently, the stress wave of impact energy will propagate to the next least resistive layer 128 positioned maximally distal from layer 127 so as to fully or partially crush it and load and partially crush interceding layers 129, which will fully or partially crush lastly. In the exemplary embodiment, layer 125 is thickest, layer 126 next thickest, layer 127, next thickest, layer 120 next thickest and layer 129 is the least thick of the layers creating a compound exponentially shaped response of an appropriate order to cushion the driver from the intrusive impact.

In FIG. 22B, an embodiment is depicted that protects the driver from a decelerative impact, for example, a racecar impacting with a concrete barrier. The layers of energy absorbing materials are positioned such that the layer 125 with the least compressive and/or crush strength is adjacent to the chassis or monocoque of the racecar, the layer 126 of next greatest compressive and/or crush strength is closest to the helmet of the driver, the layer 127 of next greatest compressive and/or crush strength is positioned adjacent layer 125 towards the driver, the layer 128 of next greatest compressive and/or crush strength is positioned adjacent layer I26 towards the chassis or monocoque of the racecar, and the layer 129 of next greatest compressive and/or crush strength is positioned in the middle of the five layer module. In the exemplary embodiment, layer 129 is of greatest density, layer 128 next densest, layer 127 next dense, layer 126 next dense and layer 125 least dense of the layers. On a decelerative impact in which the rnonocoque or chassis structure 130 of the car impacts an object such as a concrete barrier, the drive:r's body and head are forced against the racecar structure 130 compressing the mufti-phase energy absorbing and impact attenuating module 10 as it does so. Impact energy and forces load the mufti-phase energy absorbing and impact attenuating module 10 such that the layer least resistive to the impact energy and forces will compress firstly. Thus, although the stress wave of impact energy will propagate through, load and partially compress interceding layers I26, I28, 129 and 127, layer I25 maximally distal to the impact will preferentially partially or fully crush. Layer 126 next least resistive to the impact energy and force located maximally distal from layer 125 will partially or fully crush next preferentially causing propagation of the stress wave of impact energy to travel a maximum amount and load and partially compress interceding layers 127, 129 and 128. Subsequently, the stress wave of impact energy will propagate to the next least resistive layer 127 positioned maximally distal from layer 126 so as to fully or partially crush it and load and partially crush interceding layers 128 and 129.
Subsequently, the stress wave of impact energy will propagate to the next least resistive layer 128 positioned maximally distal from layer 127 so as to fully or partially crush it and load and partially crush interceding layers 129, which will partially or fully crush lastly. In the exemplary embodiment, layer 125 is thickest, layer 126 next thickest, layer 127, next thickest, layer 120 next thickest and layer 129 is the least thick of the layers creating a compound exponentially-shaped response of an appropriate order to cushion the driver from the intrusive impact.
An alternate embodiment of the mufti-phase energy absorbing a.nd impact attenuating module 10 of the present invention used in the aspect of a head rest 109 and cockpit surround 120 of the same configurations as FIG. 22A and FIG. 22B as shown in FIG. 22C includes thin, pliable facing sheets 161 positioned at the boundaries of layers within the mufti-phase energy absorbing and impact attenuating module 10 to serve to further distribute and disperse impact energy.
Generally, a decelerative impact will cause greater deceleration to the head and body of the driver than an external or intrusive impact and thus a preferred embodiment may be that of the decelerative impact configuration as depicted in FIG. 228.
Crash and Sports Helmets.
Referring now to FIG. 23 and FIG. 24, FIG. 23 depicts a crash helmet 80 of prior art. An impact with the crash helmet will firstly impact the outer shell 81 causing it to deform or bend and deform the underlying foam liner 82. The inner foam liner 82 provides an energy absorbing and cushioning barrier for the head. The comfort liner 83 serves to provide a comfortable fit for the helmet but also provides some cushioning of shock to the head as well. Helmets also generally comprise a lower liner 86, visor mount 85, edge beading 84 and a chinstrap assembly 87.
FIG. 24 illustrates an exemplary mufti-phase energy absorbing and impact attenuating module 1 comprising the outer shell 91 and inner liner layers 93, 94, 95 and comfort foam 92 in the aspect of a crash helmet 98. In an exemplary embodiment, the outer shell 91, inner layers 93, 94, and 95 are concentric and annular. The outer shell comprises an injection ~~r pressure molded shell made of thermoset or thercmplastic material that may be glass fibre reinforced. The outer shell 91 has compressive strength, shear strength and tensile strength. The inner liner comprises layers 93, 94, 95 of differing density or material generally manufactured of polystyrene, polyurethane or other energy absorbing foam fused, bonded or otherwise fixed adjacent to on.e another in a concentric annular arrangement. The outer layer of the inner liner is fused, bonded or otherwise fixed adjacent to the outer shell honeycomb panel 91 in a concentric annular arrangement, as is the inner layer of the inner liner with the comfort foam layer 92. Comfort foam layer 92 may be continuous or segmented.
In FIG. 24A, an embodiment of a crash helmet 98 zs depicted that, for example, protects the wearer from an external impact striking the crash helmet 98, for example, a rock or errant part impacting the helmet. The layers of energy absorbing materials are positioned such that the comfort padding layer 92 with the least compressive and/or crush strength is closest to the head 97 of the wearer, the layer 93 of next greatest compressive and/or crush strength is adjacent to the inner surface of the outer shell 91, the layer 94 of next greatest compressive and/or crush strength is positioned adjacent comfort padding layer 92 towards the outer shell 91, the layer 95 of greatest compressive and/or crush strength is positioned between layer 93 and 94 of the module. In the exemplary embodiment, layer 95 is of greatest density, layer 94 next densest, layer 93 next dense, and layer 92 least dense of the layers. On an external impact striking the helmet, impact energy displaces the shell 91 towards the head 97 of the wearer of the helmet, compressing the mufti-phase energy absorbing and impact attenuating module 10 against the head 97 as it does so. Impact energy and forces load the multi-phase energy absorbing and impact attenuating module 10 such that the layer least resistive to the impact energy and forces will compress firstly. Thus, although the stress wave of impact energy will propagate through, load and partially compress interceding layers 93, 95, and 94, layer 92 maximally distal to the impact will preferentially partially or fully crush against the head 97. Layer 93 next least resistive to the impact energy and force located maximally distal from layer 92 will partially or fully crush next preferentially causing reflection and propagation of the stress wave of impact energy to travel a maximum amount and load and partially compress interceding layers 94 and 95. Subsequently, the stress wave of impact energy will reflect and propagate to the next least resistive layer 94 positioned maximally distal from layer 93 so as to fully or partially crush it and load and partially crush interceding layer 95 which will partially or fully crush lastly. In the exemplary embodiment, layer 92 is thickest, layer 93 next thickest, layer 94 next thickest, and layer 95 is the least thick of the layers creating a compound exponentially-shaped response of an appropriate order to cushion the head 97 from the external impact.
In FIG. 24B, an alternate embodiment of a crash helmet 98 is depicted that, for example, protects the wearer from a decelerative impact, e.g., the helmet 98 striking the roadway on a fall from a motorcycle. The layers of energy absorbing materials are positioned such that the layer 92 with the least compressive and/or crush strength is adjacent to the inner surface of the outer shell 91, the comfort padding layer 93 of next greatest compressive and/or ez°ush strength is closest to the head 97 of the wearer, the layer 94 of next greatest compressive and/or crush strength is positioned adjacent layer 92 towards the head 97 of the wearer, the layer 95 of greatest compressive and/or crush strength is positioned between layer 93 and 94 of the module. In the exemplary embodiment, layer 95 is of greatest density, layer 94 next densest, layer 93 next dense, and layer 92 least dense of the layers. On an impact of the crash helmet 98 staking an object, for example a roadway, the wearer's head 97 is forced against the mufti-phase energy absorbing and impact attenuating module comprising layers 92, 93, 94 and 95. Impact energy and forces load the mufti-phase energy absorbing and impact attenuating module 10 such that the layer least resistive to the impact energy and forces will compress firstly. Thus, although the stress wave of impact energy will propagate through, load and partially compress interceding layers 93, 95, and 94, layer 92 maximally distal to the impact of the head 97 against the helmet liner will preferentially partially or fully crush against the shell. Comfort padding layer 93 next least resistive to the impact energy and force located maximally distal from layer 92 will partially or fully crush next preferentially causing reflection and propagation of the stress wave of impact energy to travel a maximum amount and load and partially compress interceding layers 94 and 95. Subsequently, the stress wave of impact energy will reflect and propagate to the next least resistive layer 94 positioned maximally distal from layer 93 so as to fully or partially crush it and load and partially crush interceding layer 95 which will partially or fully crush lastly. In the exemplary embodiment, layer 92 is thickest, layer 93 next thickest, layer 94 next thickest, and layer 95 is the least thick of the layers creating a compound exponentially shaped response of an appropriate order to cushion the head from the external impact.
An alternate embodiment of the crash helmet 98 of the same configurations as FIG. 24A and FIG.
24B includes thin, pliable facing sheets 161 positioned at the boundaries of layers within the multi-phase energy absorbing and impact attenuating module 10 as shown in FIG. 24C
in the aspect of a crash helmet liner to serve to further distribute and disperse impact energy.
Generally, a decelerative impact will cause greater deceleration to the head and body of the driver than an external or intrusive impact and thus a preferred embodiment may be that of the decelerative impact configuration as depicted in FIG. 248.
FIG. 25 and FIG. 26 depict a sport helmet 150 of prior art. The outer shell 151 is generally made of hard thermoplastic or thermoset material. The inner liner typically comprises a single layer liner 152 of expanded polypropylene (EPP) with comfort or sizing padding 159.
Referring now to FIG. 27, a sport helmet with the mufti-phase energy absorbing and impact attenuating module 10 of the present invention in the aspect of a helmet liner is shown. The outer shell 151 is preferably made of a thermoset or thermoplastic material and consistent with the outer shell of sport helmets of prior art.

In FIG. 27A, an embodiment of a sport helmet 158 is depicted that, for example, protects the wearer from an external impact striking the helmet, for example, a hockey puck or other player impacting the helmet. The layers of energy absorbing materials are positioned such that the comfort padding layer 152 with the least compressive and/or crush strength is closest to the head of the wearer, the layer 153 of next greatest compressive and/or crush. strength is adjacent to the inner surface of the outer shell 151, the layer 154 of next greatest compressive and/or crush strength is positioned adjacent comfort padding layer 152 towards the outer shell 151, the layer 155 of greatest compressive and/or crush strength is positioned between layers 153 and 154 of the module. In the exemplary embodiment, layer 155 is of greatest density, layer 154 next densest, layer 153 next dense, and layer 152 least dense of the layers. On an external irr~pact striking the sport helmet 158, impact energy displaces the shell 151 towards the head 159 of the wearer of the helmet, compressing the mufti-phase energy absorbing and impact attenuating module 10 against the head 159 as it does so. Impact energy and forces load the mufti-phase; energy absorbing and impact attenuating module 10 such that the layer least resistive to the impact energy and forces will compress firstly. Thus, although the stress wave of impact energy will propagate through, load and partially compress interceding layers 153, 155, and 154, layer 152 maximally distal to the impact will preferentially partially or fully crush against the head 159. Layer 153 next least resistive to the impact energy and force located maximally distal from layer 152 will partially or fully crush next preferentially causing reflection and propagation of the stress wave of impact energy to travel a maximum amount and load and partially compress interceding layers 154 and 155.
Subsequently, the stress wave of impact energy will reflect an propagate to the next least resistive layer 154 positioned maximally distal from layer 153 so as to fully or parl:ially crush it and load and partially crush interceding layer 155 which will partially or fully crush lastly. In the exemplary embodiment, layer 152 is thickest, layer 153 next thickest, layer 154 next thickest, and layer 155 is the least thick of the layers creating a compound exponentially-shaped response of an appropriate order to cushion the head from the external impact.
In FIG. 27B, an alternate embodiment of a sport helmet 158 is depicted that, for example, protects the wearer from a decelerative impact of the helmet, e.g., the sport helmet 158 striking the roadway on a fall from a bicycle, skateboard or roller blades. The layers of energy absorbing materials are positioned such that the layer 1 S2 with the least compressive an.d/or crush strength is adjacent to the inner surface of the outer shell 151, the comfort padding layer 153 of next greatest compressive and/or crush strength is closest to the head 159 of the wearer, the Payer 154 of next greatest compressive and/or crush strength is positioned adjacent layer 152 towards the head 159 of the wearer, the layer 155 of greatest compressive and/or crush strength is positioned between layer 153 and 154 of the module. In the exemplary embodiment, layer 155 is of greatest density, layer 154 next densest, layer 153 next dense, and layer 152 least dense of the layers.
On an impact of the sport helmet 158 striking an object, for example a roadway, the wearer's head 159 is forced against the mufti-phase energy absorbing and impact attenuating module 1C~ comprising layers 152, 153, 154 and 155. Impact energy and forces load the mufti-phase energy absorbing and impact attenuating module 10 such that the layer least resistive to the impact energy and forces will compress firstly.
Thus, although the stress wave of impact energy will propagate through, load and partially compress interceding layers 153, 155, and 154, layer 152 maximally distal to the impact of the head against the liner will preferentially partially or fully crush against the shell 151. Comfort padding layer 153 next least resistive to the impact energy and force located maximally distal from layer 152 will partially or fully crush next preferentially causing reflection and propagation of the stress wave of impact energy to travel a maximum amount and load and partially compress interceding layers 154 and 155. Subsequently, the stress wave of impact energy will reflect and propagate to the next least resistive layer 154 positioned maximally distal from layer I 53 so as to fully or partially crush it and load and partially crush interceding layer 155 which will partially or fully crush lastly. In the exemplary embodiment, layer 152 is thickest, layer 153 next thickest, layer 154 next thickest, and layer 155 is the least thick of the layers creating a compound eXponentially-shaped response of an appropriate order to cushion the head from the extet-nal impact.
An alternate embodiment of the sport helmet 158 of the same configuration as FIG. 27A and FIG.
27B includes thin, pliable facing sheets positioned at the boundaries of :layers within the mufti-phase energy absorbing and impact attenuating module 10 in the aspect of a sport helmet liner to serve to further distribute and disperse impact energy. FIG. 28 depicts the sport helmet 158 of the same configuration as FIG. 27B, but with thin, pliable facing sheets 1 < 1 positioned at the boundaries of layers 153 and 155, layers 155 and 154, and layers 154 and 152 to serve to further distribute and disperse impact energy.
Generally, a decelerative impact will cause greater deceleration to the head and body of the driver than an external or intrusive impact and thus a preferred embodiment may be that of the decelerative impact configuration as depicted in FIG. 27B.

5g FIG. 29 shows an exemplary mufti-phase compound exponentially-shaped stress versus strain response achieved with the mufti-phase energy absorbing and impact attenuating module 10 in the aspect of a crash helmet liner or sport helmet liner as depicted in FIG. 24 and FIG. 27 respectively in which changes in impact dynamics and decelerative forces are gradual and integrated rather than abrupt, and a gradually increasing cushioning of the impact occurs.
FIG. 30 shows an exemplary mufti-phase compound exponentially-shaped stress versus strain response achieved with the mufti-phase energy absorbing and impact attenuating module 10 of a different order in which changes in impact dynamics and decelerative forces are gradual and integrated rather than abrupt, and a gradually increasing cushioning of the impact occurs but the impacting body is decelerated more slowly for a longer period a.nd deflection of the mufti-phase energy absorbing and impact attenuating module 10 and then decelerated more quickly for the remainder of the deflection of the mufti-phase energy absorbing and impact attenuating module 10 as compared to FIG. 29 in a manner that may be advantageous for relatively low impact energies yet have the capacity to accommodate higher impact energies eivfectively.
FIG. 31 shows an exemplary mufti-phase compound exponentially-shaped stress versus strain response achieved with the mufti-phase energy absorbing and impact attenuating module 10 of a different order in which changes in impact dynamics and decel~rative forces are gradual and integrated rather than abrupt, and a gradually increasing cushioning of the impact occurs but the impacting body is decelerated more quickly initially and for less deflection of the mufti-phase energy absorbing and impact attenuating module 10 and then decelerated more quickly for the remainder of the deflection of the mufti-phase energy absorbing and impact attenuating module 10 as compared to FIG. 30 in a manner that may be advantageous i=or relatively high impact energies yet have the capacity to accommodate even higher impact energies effectively.
By utilizing varying mufti-phase compound exponentially-shaped stress versus strain response achieved with the mufti-phase energy absorbing and impact attenuating module 10, the same helmet design can be used with liners of common total thickness T, but: with varying abilities to absorb impacts, e.g., low impact energy for children's or recreational helmets, yet higher impact absorbing capacity for elite or professional athlete's helmets.

Conceivably, those persons knowledgeable in this field of endeavor will, upon studying this disclosure, consider various modifications and/or improvements to the inventive concept presented, but still within this concept. Though primarily designed for the embodiments and aspects as mentioned herein, this in no way limits the use of the present invention. In fact, similar mufti-phase, energy absorbing and impact attenuating modules may be useful in a wide variety of applications in which energy absorption and impact attenuation of an incident body to minimize injury and damage are desired. Therefore, the invention herein is not to be limited t~o the preferred or other embodiments and aspects set forth as exemplary of the invention, but only by the scope of the claims and the equivalents thereto.

REFERENCES:
Yasui, Yoshiaki. Dynamic axial crushing of mufti-layer honeycomb panels and impact tensile behavior of the component members. International Journal of Impact Engineering. Vol. 24;
No. 6. 2000. pp. 659-671.