WO2003085223A1 - Systeme de mat de securite absorbant les chocs comportant une substructure elastomere - Google Patents

Systeme de mat de securite absorbant les chocs comportant une substructure elastomere Download PDF

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Publication number
WO2003085223A1
WO2003085223A1 PCT/US2003/010206 US0310206W WO03085223A1 WO 2003085223 A1 WO2003085223 A1 WO 2003085223A1 US 0310206 W US0310206 W US 0310206W WO 03085223 A1 WO03085223 A1 WO 03085223A1
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WO
WIPO (PCT)
Prior art keywords
column
mat
zone
resilient
wall
Prior art date
Application number
PCT/US2003/010206
Other languages
English (en)
Inventor
Richard P. Scott
Bryce L. Betteridge
Original Assignee
Seamless Attenuating Technologies, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Seamless Attenuating Technologies, Inc. filed Critical Seamless Attenuating Technologies, Inc.
Priority to AU2003224830A priority Critical patent/AU2003224830A1/en
Publication of WO2003085223A1 publication Critical patent/WO2003085223A1/fr

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04F—FINISHING WORK ON BUILDINGS, e.g. STAIRS, FLOORS
    • E04F15/00—Flooring
    • E04F15/22—Resiliently-mounted floors, e.g. sprung floors
    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47G—HOUSEHOLD OR TABLE EQUIPMENT
    • A47G27/00—Floor fabrics; Fastenings therefor
    • A47G27/02—Carpets; Stair runners; Bedside rugs; Foot mats
    • A47G27/0212—Carpets; Stair runners; Bedside rugs; Foot mats to support or cushion
    • A47G27/0231—Carpets; Stair runners; Bedside rugs; Foot mats to support or cushion for fighting fatigue
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04F—FINISHING WORK ON BUILDINGS, e.g. STAIRS, FLOORS
    • E04F15/00—Flooring
    • E04F15/02—Flooring or floor layers composed of a number of similar elements
    • E04F15/10—Flooring or floor layers composed of a number of similar elements of other materials, e.g. fibrous or chipped materials, organic plastics, magnesite tiles, hardboard, or with a top layer of other materials
    • E04F15/105—Flooring or floor layers composed of a number of similar elements of other materials, e.g. fibrous or chipped materials, organic plastics, magnesite tiles, hardboard, or with a top layer of other materials of organic plastics with or without reinforcements or filling materials
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04F—FINISHING WORK ON BUILDINGS, e.g. STAIRS, FLOORS
    • E04F15/00—Flooring
    • E04F15/18—Separately-laid insulating layers; Other additional insulating measures; Floating floors
    • E04F15/185—Underlayers in the form of studded or ribbed plates
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04F—FINISHING WORK ON BUILDINGS, e.g. STAIRS, FLOORS
    • E04F15/00—Flooring
    • E04F15/22—Resiliently-mounted floors, e.g. sprung floors
    • E04F15/225—Shock absorber members therefor

Definitions

  • the invention relates to systems for attenuating applied force and absorbing impact energy; more particularly, it relates to safety and antifatigue matting and elastomeric subsurface structures and deformable structures for attenuating applied force and absorbing impact energy; more particularly it relates to impact absorbing safety matting system with elastomeric subsurface structures and deformable structures for attenuating applied force and absorbing impact energy in healthcare, recreation, industry and home impact surfaces.
  • hip fractures are the most common and the most severe.
  • the loss of mobility following a hip fracture is itself a potentially fatal risk and many elderly patients never return to normal activity after a fall.
  • Proposed strategies include the use of protective hip pads, cushioned flooring and the promotion of exercise programs to increase the strength and agility of at-risk individuals. We review the injury reduction potential of cushioned floors, and calculations as to the effect of compliant flooring materials on the peak impact force acting at the hip.
  • the fracture strength of the femoral head has been estimated using mechanical tests of cadaveric specimens, finite element modeling and predictions based on material properties. From such studies, the peak lateral loads inducing fractures in older individuals range from 1000 to 6000 N. Younger subjects have greater femoral strength. Fracture strength depends on many factors, including the loading conditions and the age, body size and bone mineral density of the subject.
  • the force acting at the hip during a fall is affected by a number of factors, most notably the impact velocity, the effective mass involved in the impact, the material properties of the soft tissue overlying the hip and the properties of the surface against which the impact occurs.
  • a group of researchers from Harvard University and Harvard Medical School (Robinovitch et al, 1991) used a constrained release experiment to determine the non-linear stiffness and damping properties of soft tissue and used their results to calculate the impact force on a hard surface.
  • the predicted impact force magnitudes were similar to the breaking strength of the femoral neck, supporting the idea that unprotected falls onto hard surfaces can break the hip.
  • the Harvard hip impact model uses non-linear stiffness and damping functions to describe the viscoelastic properties of the soft tissue overlying the hip and documents the soft tissue parameters for males and female subjects across a range of soft tissue thicknesses.
  • Figure 22 is a schematic of the Harvard hip impact model, in which impact of the falling mass m is moderated by the compliant material properties of the soft tissue.
  • Soft tissue behavior is characterized by non-linear stiffness (k and damping (C j ) functions. Equation of Motion
  • the model In order to calculate the peak force of an impact, the model requires parameters for soft tissue properties, the effective mass and a description of the initial conditions (e.g. impact velocity) defining the impact.
  • Soft Tissue Properties Robinovitch (1991), gives non-linear functions for k t and c t for both males and females and for different muscle activation states. For the purposes of the analysis presented here, values for male subjects in a muscle-relaxed state were used. Specifically,
  • Robinovitch (1991) reports the average effective mass ( ) involved in hip impact to be
  • Van den Kroonenberg et al (1993) report estimated hip-floor impact velocities ranging from 2.14 to 4.25 m s "1 and averaging 3.19 m s "1 .
  • Equation 1 is integrated using the properties shown in Equations 2 - 4 and the initial conditions.
  • Figure 23 shows the force vs. time curve thus calculated.
  • the peak force of 7022 N at 21.6 ms is similar to the value of 7120 N at 21.6 ms read from the graph in Figure 6 of Robinovitch (1991).
  • the 1.4% difference in peak force can be attributed to differences in the numerical integration techniques employed, or to errors in measuring peak force values from the graph.
  • closed cell foam typically provide dangerous surface deformation levels; this often leads to foot lock or foot entrapment in football games played on surfaces having a foam substructure. Closed cell foam also fails to adequately protect against injuries from serious or 'bottoming-out' impacts.
  • mats in the market place are also flimsy. They are easily damaged by carts and vehicles that impact the edge of the mat. The replacement frequency is high for mats in these settings. Though the center of the mat is not worn out, the edge is damaged and therefore must be replaced. The mats also easily flip up or bunch up creating trip hazards.
  • a impact absorbing safety matting system with a preferably continuous array of elastomeric subsurface structures for use beneath a surface layer and beneath artificial turf, poured urethanes, sheet flooring, or other synthetic surface.
  • the elastomeric subsurface structures are preferably geometric in shape, such as for example cylindrical shapes surrounding a void, the void optionally surmounted or topped by a dome.
  • the disclosed impact absorbing safety matting system is advantageously employed for protecting workers, players or residents from accidental fall impacts or sports activity impacts (such as, but not limited to, football or aerobic activities) with an otherwise unprotected ground or floor impact surface.
  • Use of preferred impact absorbing safety matting systems for antifatigue purposes is also disclosed.
  • the array of defined structures described herein is effective at providing worker/resident/player support with a relatively more stable, relatively less deformed, surface layer that does not lead to foot entrapment yet provides effective impact and bottoming-out protection.
  • Disclosed embodiments may also advantageously serve as a protective system to be installed over a hard surface where falls to the ground are likely.
  • Zones under exercising equipment on school playgrounds, day care centers, and playlands adjacent to fast food restaurants are examples of areas where disclosed safety matting embodiments can be used to minimize injuries that are likely to occur in such play environments.
  • Athletic fields for football, soccer, baseball, and the like are areas where they can be used to minimize injuries that are likely to occur in such sports environments.
  • a novel resilient substructure is disclosed. It may advantageously be used as part of a safety matting and antifatigue matting system discussed below, or used independently where substructure attenuation is thought desirable.
  • the substructure includes a resilient column and a column wall, with the wall surrounding a central void in the column.
  • the void opens at a bottom of the column.
  • the column has in a bottom region of the column wall a lower zone that is a more compressible, relatively collapsible zone, and in an upper region of the column wall above the lower zone an upper zone that is a less compressible, relatively uncoUapsible zone.
  • the lower zone is preferably between about 0.4 - 0.5 and preferably 0.46 inches in height measured from the bottom of the column.
  • the column wall has a cross- sectional thickness that increases from the bottom of the wall to a point where the wall thickness is 120-125% of the thickness of the wall measured at the bottom of the wall, and that point defines an approximate and virtual upper boundary to the lower zone.
  • a column may optionally have a vertical stiffening rib along a portion of the upper zone of the column wall and the stiffening rib increases in thickness at heights above a rib bottom, with the rib optionally connecting two columns.
  • the column is preferably tapered upwardly, both inside and out, with an outside draft angle >1 degree and ⁇ 5 degrees, and an inside draft angle >0 degrees and ⁇ 5 degrees. Preferably, the outside draft angle is greater than the inside draft angle.
  • the substructure and mat system are comprised of elastomeric material having compression modulus of between 0.5 and 0.9 and a Shore A durometer of 40-50, preferably about 0.69 and about 44 respectively.
  • each column wall surrounds a central void in the column, the void opening at a bottom of the column.
  • the column has in a bottom region of the column wall a lower zone that is a more compressible, relatively collapsible zone, and in an upper region of the column wall above the lower zone an upper zone that is a less compressible, relatively uncoUapsible zone.
  • the resilient mat system optionally has an integral ramp upon at least one edge of the mat, and a set of single ribs may connect a peripheral outer border of columns to a base of the integral ramp.
  • the resilient mat system optionally has a relatively rigid ramp structure bordering at least one mat on at least two sides, and the ramp structure is preferably attached to a floor base to retain the mat, whereby the mat is removable from the border of the ramp. Alternatively, the ramp structure is attached to at least a portion of the mat.
  • the resilient mat system takes advantage of a unique fenestrated connector, where the connector fenestrations are sized and numbered to receive the bases of a plurality of columns, and the connector has a bend forming a lip that an edge of the ramp fits into for attachment of the ramp to the mat.
  • An alternate fenestrated connector has holes sized and numbered to receive the bases of a plurality of columns from at least two mats such that with column bases of two mats engaged in the respective holes of the connector, the two mats are joined in a selected spaced relationship.
  • One selected spaced relationship is for the two mats to be held to have a selectably sized gap between them, the width of the gap depending upon the spacing of the fenestrations in the connector.
  • An alternate gap holding mechanism is to use a gap spacer in between selected mats at selected locations to establish and maintain a gap, whether or not the fenestrated connector is employed to hold the mats together, such as when the mats are otherwise corralled inside a border of ramp attached to a base floor. This would allow gap setting, while taking full advantage of the ease of removability of such mate inside the ramp corral.
  • the recognized methodology for testing the shock attenuating properties of playground and athletic surfacing systems is the ASTM F-355 test which uses three different objects at impact velocities appropriate for the intended end-use: first, a cylindrical missile, weighing twenty pounds, and having a circular, flat, metallic, impacting face of twenty square inches; second, a metallic hemisphere weighing fifteen pounds and having an impacting surface with a radius of 3.25 inches; and third, a metallic headform weighing eleven pounds (five kilograms).
  • the report section within the F-355 test methodology lists various ways to collect and analyze data. The two most important measurements of the shock attenuating characteristics of a surfacing system are the G-max and the Severity Index.
  • a G-max of 200 and a Severity Index of 1,000 are internationally recognized as the threshold for a skull concussion for a human being.
  • Embodiments disclosed herein provide a safety matting system that will not exceed a G-max reading of 200 nor a Severity Index value of 1,000 when tested with any of the three objects listed in the F-355 test methodology over a broad temperature range.
  • Many preferred embodiments disclosed also provide ASTM F-1292 fall height protection from 1 to 10 feet (using ASTM F-355, hemispherical missile - procedure C) depending on the thickness of the embodiment.
  • Preferred embodiments reduce impact forces from 10% to 60% on the hip, depending on the thickness of the embodiment and on the weight of the subject.
  • the elastomeric structures disclosed preferably flex more at the base of the sub-structure than at the top of the substructure, thus reducing foot entrapment effects and other surface disturbances around the foot.
  • Preferred structures provide greater protection against bottoming out (also referred to as sudden loss of impact attenuation) by providing a structure with at least two zones of different compressibility.
  • the one zone or lower zone of the structure is defined by the collapsible 'foot' of the cylinder (or other shape of the elastomeric substructure) and the second zone or upper zone is defined by the relatively less compressible upper portion or the substructure shape, or alternatively by the portion of the substructure shape that is contiguous to, or reinforced by, the elastomeric links (also sometimes referred to herein as 'bridges') that preferably link the cylinders to each other.
  • the elastomeric links also sometimes referred to herein as 'bridges'
  • the array of domed geometric cylinders are preferably covered with a solid sheet of elastomer fenestrated with a corresponding array of drain holes between the cylinders.
  • the cylinders may be beveled or tapered inside so the wall thickness is thicker near the top of the void and thinner at the base of the domed cylinder.
  • the cylinder may be also be shaped in horizontal cross section in any elliptical or many-sided regular or irregular shape (such as for example, but not limited to, hexagon or octagon shaped).
  • Disclosed structures also isolate and absorb vibrations induced by sources of turning, impacting or bouncing induced vibrations, such as found in the turning of propellers, working engines, other machinery, or the rolling of wheels over non-smooth surfaces.
  • a preferred elastomeric mat sits in a rigid frame to prevent damage to the mat and therefore increase its useful life.
  • the rigid frame is preferably attached to the floor for greater safety, preventing the mat from flipping over or bunching up in response to a side impact.
  • Disclosed clips and various conventional methods of damming, taping and gluing can be used to connect a disclosed vertical ramp face to the preferred mat or to the floor or other support surface to create a semi-permanent installation.
  • Preferred embodiments provide an elastomeric substructure in a geometric shape that flexes under load or impact and provides a surface condition that reduces both the rate of foot, leg and back fatigue, as well as overall foot, leg and back fatigue, in standing workers. It also provides a surface that absorbs impact energy from a falling hip, reducing impact force measured at the hip by about 10% to about 60% as compared to a 'hard' surface, thus significantly reducing the probability and severity of hip fracture. It also provides a surface that absorbs impact energy from a falling head, preventing concussion level injuries at critical heights below 10 feet.
  • Preferred elastomeric mats are have a top surface that is supported by multiple flexing elastomeric cylinders that are more readily deformable or compressible, and actually flex more, at the floor surface than at the top surface. This structure provides a more stable work surface.
  • Embodiments in the form of elastomeric mats preferably have sloped edges or built-in ramps for single mat or 'throw' mat applications, or relatively rigid ramps at the edges of an elastomeric mat array that are significantly harder than the elastomeric matting itself, and that advantageously protect the matting from damage from impacts such as those caused by carts, vehicles or other such devices, and that prevent tripping of workers as they walk up onto or off of the matting.
  • Mats also alternatively have rigid ramps that are removably attached by optionally semi-permanent means to a floor or other sub-base impact surface such as by screw or double-back sticky tape or glue or the like, such that the ramps can be removed if necessary.
  • Preferred ramps may be advantageously colored yellow or otherwise highlighted so the work area draws the attention of the worker as he or she walks up on or off the elastomeric matting.
  • Figure 1 is a cross- sectional view of one embodiment of elastomeric mat.
  • Figure 2 is a cross-sectional view of an alternate embodiment of elastomeric mat.
  • Figure 3 is a bottom plan view of the mat of Figure 1.
  • Figure 4 is a bottom plan view of the mat of Figure 2.
  • Figure 5 is a top plan view of a group or array of mats with a rigid ramp attached around three sides of the mat array.
  • Figure 6 is a side cross-sectional view of the clip of Figure 7.
  • Figure 7 is a top plan view of a fenestrated or holed joining clip.
  • Figure 8 is a top plan view of an alternate fenestrated or holed joining clip.
  • Figure 9 is a bottom perspective view of a mat.
  • Figure 10 is a cross-sectional view of a rigid ramp abutted to a mat.
  • Figure 11 is a cross-sectional view of a ramp abutted to a mat, with the clip of Figure 7 joining the ramp and mat.
  • Figure 12 is a cross-sectional view of a top surface spacer.
  • Figure 13 is a cross-sectional view of the clip of Figure 8.
  • Figure 14 is a force - displacement curve showing material compression range for 8 different embodiments.
  • Figure 15 is a stress-strain curve showing material response to stress for 8 different embodiments.
  • Figures 16 a-b are schematics of a conventional closed cell foam cushion at rest and under load, respectively.
  • Figures 17 a, b are pictures of disclosed embodiments of elastomeric structure, at rest and under load, respectively.
  • Figures 18 a, b are pictures of a foot lock simulation test.
  • Figures 19 a, b are pictures of an elbow penetration simulation test.
  • Figure 20 is a graph of force displacement curves for 9 different embodiments.
  • Figure 21 is a graph of stress displacement curves for the disclosed structure.
  • Figure 22 is a schematic diagram of Harvard hip impact model and supporting equations.
  • Figure 23 is a graph of force vs. time for an example solution of a hip impact on a hard surface.
  • Figure 24 is a schematic diagram of a new model for Hip Impact.
  • Figure 25 is a graph of peak impact force comparisons for 7 embodiments of the structure.
  • Figure 26a,b,c are force vs. time curve graphs for hard surface as compared to 17 mm, 26 mm and 48 mm embodiments of the structure.
  • Figure 27a-d are graphs illustrating an analysis of data.
  • Figure 28 is a graph illustrating fatigue reduction as a function of mat hardness.
  • Figure 29 is a graph of a disclosed embodiment as compared to two competing implementations .
  • Figure 30 is a graph of a disclosed embodiment as compared to two competing implementations.
  • Figure 31 is a sectional elevation of an embodiment of the disclosed mat.
  • Figure 32 is a sectional elevation of an alternate embodiment of the disclosed mat.
  • Figure 33 is a section taken along lines 33-33 of Figure 32.
  • the resulting peak force for an impact on concrete is 24,300N, more than four times the peak force predicted by the Harvard model and well in excess of the force required to fracture the hip. The value is not unreasonable, compared with measured peak forces from real impacts with similar impact energy on compliant surfaces of similar thickness to the soft tissue. This approach essentially maximizes the shock attenuation capacity of the soft tissue within the limits of the available soft tissue thickness.
  • Non-linear Hip Impact Model with Shock Attenuating Surface Figure 24 shows the new hip impact model with the addition of a non-linear spring representing the elasticity of the surface against which the impact occurs.
  • the impact of the falling mass, m is moderated by the compliant material properties of the soft tissue and the surface, which act in series.
  • Soft tissue behavior is characterized by the non-linear stiffness function previously described. Damping is ignored.
  • the two degrees of freedom of motion of the system are expressed as x m , the displacement of the mass, and x s , the compression of the surface. Equation of Motion
  • the stiffness of the surface material is a function not only of its material properties, but also of the geometry of the contact.
  • the surface will behave like a more or less stiff spring, depending on the contact area and the curvature of a body contacting it.
  • the Harvard model does not incorporate contact geometry, and the geometry of contact between the hip and the surface is unknown.
  • the contact was assumed to that of a rigid, penetrator with a 0.08m radius, flat contact area.
  • a selection of embodiments of the disclosed matting systems were mechanically tested on a Tinius Olsen UTM to determine force-displacement relationships and stiffness values. In each case, the force-displacement relationship was expressed in the non-linear form
  • Table 2 shows the calculated peak force of a hip impact on each of the test surfaces, assuming an impact velocity of 4.25 m s "1 and an effective mass of 39 kg. These results are also graphically illustrated in Figures 25 and 26a-c.
  • Figure 1 is a cross-sectional view of one embodiment of elastomeric mat with domed cylinders with sloped or tapered walls and a top surface and elastomeric linkages or bridges.
  • Figure 2 is a cross-sectional view of an alternate embodiment of elastomeric mat with domed cylinders with sloped walls and top surface, but without elastomeric bridges.
  • Figures 3 and 4 are bottom plan views of the mats of Figures 1 and 2, respectively.
  • Figure 5 is a top plan view of a group or array of mats with a rigid ramp attached around three sides of the mat array.
  • Elastomeric mat 4 has a top surface 1 with underlying subsurface hollow domed cylinders 2.
  • elastomeric cylinders may or may not be tapered on the inside of the cylinder as can be seen at 2 in Figure 2 (exaggerated).
  • the material properties of elastomeric cylinders are described with a data plot and accompanying table in Figures 14 and 15.
  • Lower zone 6 of cylinder 2 is the zone that first flexes or deforms or collapses as load is gradually applied to top surface 1 of mat 4.
  • Elastomeric bridges or linkages 3 link cylinders 2 together in some embodiments.
  • Such linkages provide added stability and rigidity to an upper zone of cylinder 2 and render the upper zone relatively incollapsible as load is applied, as compared with the relatively more flexible, compressible, and collapsible lower zone or foot 6 of cylinders 2 which do not have such linkages.
  • Elastomeric mat 4 is preferably made of conventional rubber and other conventional elastomer molding technology. Mat sizes depend on the size of the mold used, which can vary from small rectangles of perhaps 1 inch square to large rectangles of 100 square feet or more. Mats 4 are abutted together as in Figure 5 and then can be surrounded by a ramp 5 for ease of walking up on or walking off the mat surface. Sloped edges or integral ramps may also be molded in to the mat and made of the same material as the mat.
  • Figure 6 is a side cross-sectional view of the clip of Figure 7.
  • Figure 7 is a top plan view of a fenestrated or holed joining clip for use in connecting a ramp piece to a mat.
  • Figure 8 is a top plan view of an alternate fenestrated or holed joining clip for use in connecting neighboring mats in an array of mats. Grid spacing between rows of holes in the clip cause mats to be joined so as to provide a drainage space between mats for liquids to flow from the top surface down between the mats, or the grid spacing of the holes of the clip can fit the mats tightly next to each other.
  • Clip 12 with holes 7 as seen in figure 8 can be used to adjoin neighboring pads as shown in figure 13 forming larger surface areas.
  • Clip 11 with holes 7 as seen in Figure 7 can be used to adjoin ramps to mats or pads 4 as shown in figure 11.
  • Figure 9 is a bottom perspective view of a mat that has elastomeric bridges between flexing cylinders.
  • Figure 10 is a cross-sectional view of a rigid ramp 5 abutted to mat 4.
  • Ramp 5 is attached to the floor surface in preferred embodiments by screws 8, but can also be attached by glue or other suitable means.
  • the mat can be attached to the vertical ramp face by glue or clip (see Figure 11).
  • Figure 11 is a cross-sectional view of a ramp abutted to a mat, with the clip of Figure 7 joining the ramp and mat.
  • regions of relatively firmer support 15 and adjacent regions of relatively softer support 16. correspond respectively to the region 15 just about the supporting column, while region 16 is anything left over that is not above a supporting column. In preferred embodiments with about a 5/8 inch upper column width and columns spaced on 3/4 inch centers, the firm zone 15 will be about 5/8 inch in diameter every 3/4 inch, and the rest will be region(s) 16.
  • Figure 12 is a cross-sectional view of top surface spacer 14 advantageously used to keep mats spaced in an array a selected distance apart. This structure is advantageously used underneath carpet, artificial turf or other permeable surface coverings to allow drainage of liquids between the mats or pads. Clip 12 as seen in Figure 13 or top surface spacer 14 as seen in Figure 12 can be used to set the spacing between mats to allow liquid to pass down between the mats if needed.
  • Figure 13 is a cross-sectional view of clip 12 of Figure 8 joining neighboring mats 4 and providing a selected spacing between them.
  • a material compression test was run on a Tinius Olsen UTM machine with a compression rate of 1.0 mm s "2 to generate the results in Table 3.
  • Figure 14 is a force vs. displacement curve showing material compression range for the 8 different samples from the above table.
  • Figure 15 is a stress vs. strain curve showing material response to stress for the
  • Figures 16 a-b are schematics of a conventional closed cell foam cushion at rest and under load, respectively.
  • the foam cushion shows an unstable condition as the surface deforms under the load, leading potentially to dangerous binding of a foot due to the surface deformation. Impact energy is absorbed by crushing the foam cells from top to bottom, and the material gets just gets 'harder' under load.
  • Figures 17 a, b are pictures of disclosed embodiments of elastomeric structure, at rest and under load, respectively. Note that as the structure takes impact or load, surface deformation is minimal, there is no tendency to bind a foot, impact energy is absorbed by 'controlled' buckling or collapse of the structure (cylinder is illustrated) at a lower zone of the structure, not at the top of the structure. The material thus gets 'softer' under load, as the collapsible structure continues to deform.
  • Figures 18 a, b are pictures of a foot lock simulation test, showing conventional foam backed artificial turf and one of the disclosed elastomeric structures covered with artificial turf, respectively. In each case the foot is planted with 500 pounds of force.
  • the degree of top surface deformation in the foam (18a) is evident as compared with the minimal deformation in the disclosed structure surface.
  • Figures 19 a, b are pictures of an elbow penetration simulation test, showing conventional foam backed artificial turf and one of the disclosed elastomeric structures covered with artificial turf, respectively.
  • the elbow is planted with 500 pounds of force.
  • the degree of bottoming out in the foam (19a) is evident as compared with the appreciable penetration with no bottoming out in the disclosed structure surface.
  • Table 4 contains results of constant velocity force- displacement test to 50% strain at 1 mm s '1 on a Tinius Olsen UTM to generate force displacement curves, presented for 9 different embodiments of disclosed structure, including measured elastic modulus and stiffness properties.
  • Figure 20 is a graph of force (stress) displacement curves for the 9 different embodiments of disclosed structure shown in the above table. Energy absorption capability is unique as exemplified by shape of the force-displacement curve. The area under each curve is the amount of energy absorbed by that sample.
  • Table 5 contains drop test data presented for 3 different embodiments of disclosed structure, including Gmax and HIC data for the structures in a 1.75 inch thick Smart Cells ® Mat embodiment at 55°F. Data measured according to ASTM F-1292 and F-355 tests.
  • Figure 21 is a graph of stress displacement curves for an embodiment of the disclosed structure as compared to two competitive implementations. For a given displacement the disclosed structure absorbs more energy than competitive products (area under the curve is the greatest for the disclosed sample).
  • Figure 22 is a schematic diagram of Harvard hip impact model and supporting equations.
  • Figure 23 is a graph of force vs. time for an example solution of a hip impact on a hard surface using the Harvard model.
  • Figure 24 is a schematic diagram of a new model for Hip Impact using accurate soft tissue component and structure component.
  • Figure 25 is a graph of peak impact force comparisons for 7 embodiments of the structure as if a hip were impacting the structure.
  • Figure 26a,b,c are force vs. time curve graphs for hard surface as compared to 17 mm, 26 mm and 48 mm embodiments of the structure.
  • Figure 27a-d are graphs illustrating an analysis of data from the literature, showing the effects of different surface materials on perception of fatigue.
  • Figure 28 is a graph illustrating fatigue reduction as a function of mat hardness.
  • the middle vertical bar indicates optimal performance by one of the embodiments disclosed herein, while the vertical bars to the left and right indicate performance by competitor models that are either too hard or too soft.
  • Figure 29 is a graph of a disclosed embodiment as compared to two competing implementations. Mat stiffness, as a function of pressure applied to the mat, initially increase, over a very small initial pressure range, but then for the disclosed embodiment dramatically falls off as pressure is increased, illustrating the unique property of disclosed embodiments that they actually get softer as pressure is applied.
  • Figure 30 is a graph of a disclosed embodiment as compared to two competing implementations, plotting mat compliance vs. pressure applied to the mat.
  • Figure 31 is a sectional elevation of an embodiment of disclosed mat 100.
  • Mat 100 has upper layer 110, also sometimes referred to herein as surface layer. Upper layer 110 is supported by column 120.
  • Column 120 may be any ready and appropriate shape, but regular geometric shapes are preferred, and a cylindrical or frusto-conical shape is advantageous in ease of production, and will be discussed here as the model for all such columns. (Except for particular discussion of the draft and other taper angles of column 120 in the frusto-conical column model, for ease of reference, the column will at times typically be referred to as a cylinder.)
  • Column 120 has a column base 127, also referred to herein sometimes as the column foot, or just the foot. It is the part of the column wall that touches the flooring or sub-base structure that underlies the matting system.
  • Column base 127 has a width d.
  • the enclosed void is optionally dome shaped 128 at the top of the void.
  • the wall of column 120 has two zones, upper zone 103 and lower zone 105; upper zone 103 is relatively resistant to collapse, unlike lower zone 105 which is designed not only to take all of the working load compression, but also the initial over load collapse or deformation, and is relatively much more compressible that upper zone 103.
  • Lower zone typical compression is attended by a moderate deformation shown at paired dotted lines 109 as a slight bulge, both outward and inward, as the compressional forces (arrows 101) work to compress the elastomeric material vertically in height and cause the material to bulge away from the wall's resting boundaries.
  • lower zone 105 actually buckles or collapses in severe deformation in the manner and in the directions indicated by paired dashed lines 107 and arrow 104.
  • the material ceases essentially to compress or bulge further, and instead collapses outwardly (relative to the center of the column) in the characteristic buckled collapse shown schematically.
  • Upper zone 103 acts mostly passively throughout both the early and then severe compression and deformation of the lower zone. Depending on forces involved and the dimensions and properties of the rubber and column, upper zone 103 will exhibit only slight bulging, schematically represented by paired dotted lines 102.
  • Zone 105 starts out at the bottom as relatively narrow in cross-section, increasing in thickness until it reaches about 20- 25% again as much thickness as it had at the bottom (120-125% of column base width d).
  • upper zone 103 could have a sudden thickness change, perhaps even by way of a thickened step at or around boundary 106, so that the increased thickness is suddenly achieved, rather than gradually.
  • Lower step 105 may likewise be 'stepped' but will remain the defined lower zone, it is believed, only while column wall thickness does not exceed about 125% of the base width d.
  • column 120 is a hollow truncated cone.
  • the void inside the cone starts at bottom opening 108 and tapers, preferably, up to the point of curvature of the optional dome top 128 of the void.
  • the outside wall of column 120 also preferably tapers upwardly until it joins with the bottom of upper layer 110.
  • the outer • wall surface thus has a draft angle ⁇ 125, and the inner wall preferably has draft angle ⁇ 123.
  • angle ⁇ 125 will be greater than angle ⁇ 123, and angle ⁇ will have a value in the range of 1 - 4.7 degrees, while angle ⁇ will have a value in the range of >0 - 4.5 degrees.
  • the preferred draft angles will be about 4.7 degrees for angle a and about 4.1 degrees for angle ⁇ .
  • boundary 106 will be located about 1.5 to 1.85 inches from the column base 127.
  • the preferred draft angles will be about 2.4 degrees for angle a and about 0.6 degrees for angle ⁇ .
  • Density of columns 120 under upper layer 110 is based on a preferred about 0.6-
  • Figure 32 is a sectional elevation of an alternate embodiment of disclosed mat 100.
  • Upper zone zl and lower zone z2 are defined in the same manner as discussed above for Figure 31.
  • Upper layer 110 has a thickness t and column 120 has a height h; mat 100 has overall thickness T.
  • preferred embodiments will have a ration of h:t > 3.5, where preferred thicknesses of upper layer 110 in various embodiments are as follows: 0.18 for Vt inch pad; 0.20-0.25 (preferably 0.22) for the 1 inch pad; and 0.25-0.35 (preferably 0.33) for the 2 inch pad.
  • Column 120 has width C at the top of the column, just under the upper layer 110.
  • the void has an uppermost width w, just before any dome 128.
  • column 120 has a stiffening rib 140 and/or a linkage or bridge 130 (connecting to other columns and to the underside of upper layer 110).
  • the effect of the rib 140 or link 130 is to make the upper zone or zl that much stiffer and so enhance the effects discussed for Figure 31 for upper zone 103 or z2 here.
  • At least one effect is that, to the extent a rib 140 or link 130 is joined to column 120, the column width at that point is significantly and effectively greater than below the rib or link, or elsewhere around the column.
  • Rib or link optionally have a taper as shown in Figure 33a, b which is a section taken along lines 33-33 of Figure 32; the taper may optionally end in a rounded rib bottom or a flat bottom.
  • the graphs of Figures 27a-d present an analysis of Redfern's data, showing the effects of different surface materials on perception of fatigue.
  • the "fatigue index” is the average of "tiredness” and “Leg Tiredness” ratings reported by Redfern.
  • a quadratic curve fitted to the data using a least squares method shows a "minimum”, i.e. a value of the material property that would appear to minimize the perception of fatigue.
  • Table 6 below lists the values of antifatigue mat properties that are thus predicted to produce the most favorable perception outcomes.
  • the appropriate "hardness" of an antifatigue mat is that produced by a material with an elastic modulus in the range 0.5 - 0.9 MPa. Redfern's data suggests an optimum value of 0.69 MPa.
  • the antifatigue mat must allow enough compression to accommodate normal loading conditions without bottoming out.
  • the optimal modulus range implies mat compression of up to 50% during normal standing and stepping, so the densification strain (bottoming out point as a percentage of thickness) must exceed 50%.
  • a properly designed antifatigue mat increases comfort and reduces tiredness and swelling of the feet and legs.
  • Antifatigue mats appear to work by reducing pressure and encouraging the body to make small postural adjustments while standing. The small movements share the work of balancing among different parts of the leg muscles, so individual muscle fibers do less work and fatigue less rapidly.
  • the postural adjustments also assist the body's "venous pump". More blood circulates back to the heart instead of pooling in the legs and feet, causing swelling.
  • Mats that are too hard or too soft are not as effective in reducing fatigue as a mat.
  • Disclosed embodiment mats are engineered for maximum fatigue reduction. See Figure 28.
  • a mat that is too hard feels less comfortable. The mat does not attenuate impact or reduce pressure on the foot as well, and does not allow the small postural adjustments that appear to reduce fatigue and improve circulation in the foot and leg, and may also focus loads on a few small muscle regions, accelerating fatigue.
  • Disclosed mats are tuned to the ideal level of compliance that research shows maximizes antifatigue performance. Optimized performance ensures stability and support while reducing pressure on the feet, reducing leg shock and maximizing fatigue reduction.
  • the disclosed structures create a regular pattern of very slightly firmer zones about 0.6 inches across and approximately 3/4 inch O.C. surrounded by very slightly softer zones.
  • One early study of compliant flooring found that such small variations in the properties of a surface mat encourage small movements of the ankle and encourage blood flow, reducing fatigue and discomfort.
  • Conventional compliant flooring materials compact and get hard when they are compressed. A foam mat that feels soft to the touch gets harder when you walk on it; harder even than some rubber mats.
  • the unique structures disclosed herein are actually firm to the touch, but then get softer as applied pressure is increased.
  • Preferred mats are made of an SBR EPDM/natural rubber elastomeric material with the following properties: Shore A Durometer of 40 to 70 (more particularly 40-50 and most preferably about 44) measured on the surface of the mat; material compression measurements made using a 90 cm 2 sample and a 1 mm s '2 compression rate as follows: stiffness of from about 100 kN per meter to about 2000 kN per meter; and modulus of from about 0.5 MPa to about 4 MPa, and more particularly at about 0.69 Mpa. Compressive modulus is believed to be optimized by controlling the product of the 300% elongation modulus figure and the Shore A durometer value.
  • Antifatigue properties are believed to be optimized in the range of 200-400 psi for 300% elongation modulus value.
  • Preferred elastomeric mats are made in thicknesses between x ⁇ inch to 3 inches, and have a top, upper or surface layer across the elastomeric substructure array.
  • This surface layer may advantageously be either a smooth or a rough surface and be either perforated or non-perforated.
  • the preferred surface layer has a thickness of from about 0.16 to 0.30 inches and more preferably 0.18, 0.20-0.25 and 0.25-0.28 inches respectively for mats nominally sized at l A inch, 1 inch and 2 inches. Other surface layer thicknesses may advantageously be employed in unusual situations.
  • Mats can be joined and then covered with conventional industrial floor coatings, or with artificial turf, carpet, vinyl, rolled rubber or poured urethane.
  • Mats can be of any conveniently manufactured size and, by abutting and joining multiple manufactured sizes, can cover an infinitely large surface area.
  • Mats are preferably prevented from moving by providing a ramp or other type of dam or wall around the mats, or by adjoining neighboring mats with a joining clip or clips as described herein, or by gluing or taping the mats to the floor surface, or to each other.
  • a preferred elastomeric substructure is a cylinder surrounding a void that tapers upwardly from a void opening of about 0.36 inches to about 0.31 inches and then is preferably domed above the taper.
  • the preferred cylinder wall thickness is about 0.10 inches and the cylinder is preferably about 0.56 inches wide at its foot or base (the end of the cylinder that touches the floor or base surface), and tapers upwardly to a diameter of about 0.6 inches.
  • Preferred substructures can be on a uniform grid or in a honey-combed configuration.
  • Preferred substructures can be of circular, elliptical, or multi-sided shape from three sided to 20 sided or more.
  • Preferred substructures can have a shared wall configuration without elastomeric bridge linkage between the cylinders on the one hand, or can alternatively be joined to one another by elastomeric linkages varying in length of from several hundredths of an inch long to about 2 inches, but preferably about 1/8 inch, and have width of from several hundredths of an inch to about l A an inch, but preferably about 1/8 inch.
  • a properly designed antifatigue mat increases comfort and reduces tiredness and swelling of the feet and legs.
  • Disclosed mats are tuned to the ideal level of compliance that research shows maximizes antifatigue performance. Optimized performance ensures stability and support while reducing pressure on the feet, reducing leg shock and maximizing fatigue reduction.
  • Conventional compliant flooring materials compact and get hard when they are compressed. The unique structures disclosed herein are actually firm to the touch, but then get softer as applied pressure is increased. Working people who must stand at their jobs are more productive when less fatigued and have less back, foot and leg pain. This generally lead to fewer accidents.

Abstract

L'invention concerne un système de mat élastique comportant au moins un mat (4) d'une épaisseur T, une couche supérieure d'une épaisseur t et une pluralité de colonnes de sous-structures élastiques de support, chaque colonne présentant une hauteur relativement uniforme h, de sorte que T=t+h, le rapport h:t étant supérieur à 3,5 pour des valeurs de T supérieures à environ 0,9 pouce. Chaque paroi de colonne entoure un vide central (2) qui se termine par une ouverture au fond de la colonne. La colonne présente, dans une région du bas de sa paroi, une zone inférieure (6) qui est moins compressible et relativement indéformable. Le système de mat élastique comporte, éventuellement, une structure inclinée (5) relativement rigide qui borde au moins un mat (4) sur au moins deux côtés, cette structure inclinée (5) étant, de préférence, fixée à une surface de base pour retenir le mat (4), ce dernier pouvant être retiré du bord de la structure inclinée (5).
PCT/US2003/010206 2002-04-02 2003-04-02 Systeme de mat de securite absorbant les chocs comportant une substructure elastomere WO2003085223A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003224830A AU2003224830A1 (en) 2002-04-02 2003-04-02 Impact absorbing safety matting system with elastomeric sub-surface structure

Applications Claiming Priority (4)

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US36966502P 2002-04-02 2002-04-02
US60/369,665 2002-04-03
US40132203A 2003-03-26 2003-03-26
US10/401,322 2003-03-26

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BE1017079A5 (nl) * 2006-03-27 2008-02-05 Tapijteenheid en tapijtrandrofielen voor het vormen van dergelijke tapijteenheid.
JP2019525783A (ja) * 2016-06-09 2019-09-12 シームレス・アテニュエイティング・テクノロジーズ・インコーポレーテッド 弾性のある表面下構造を有する衝撃吸収安全マットシステム

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US5234738A (en) * 1991-08-07 1993-08-10 Carlisle Tire & Rubber Company Resilient tile for recreation surfaces
US5509244A (en) * 1991-05-13 1996-04-23 Bentzon; Frank Flooring system having joinable tile elements, particularly plastic tiles
US5992105A (en) * 1997-06-24 1999-11-30 R & J Marketing & Sales, Inc. Spillage control safety floor matting
US6127015A (en) * 1997-03-24 2000-10-03 R & L Marketing & Sales, Inc. Floor mat system

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Publication number Priority date Publication date Assignee Title
US3438312A (en) * 1965-10-22 1969-04-15 Jean P M Becker Ground covering capable for use in playing tennis in the open air or under cover
US3808628A (en) * 1972-06-15 1974-05-07 Specialties Const Floor mat
US4948116A (en) * 1982-04-02 1990-08-14 Vaux Thomas M Impact-absorbing safety matting system for a children's play mat
US4807412A (en) * 1984-09-25 1989-02-28 Jydsk Fjederfabrik A/S Grating or mat element
US5509244A (en) * 1991-05-13 1996-04-23 Bentzon; Frank Flooring system having joinable tile elements, particularly plastic tiles
US5234738A (en) * 1991-08-07 1993-08-10 Carlisle Tire & Rubber Company Resilient tile for recreation surfaces
US6127015A (en) * 1997-03-24 2000-10-03 R & L Marketing & Sales, Inc. Floor mat system
US5992105A (en) * 1997-06-24 1999-11-30 R & J Marketing & Sales, Inc. Spillage control safety floor matting
US6405495B1 (en) * 1998-06-04 2002-06-18 Ronald Kessler Spillage control safety floor matting

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE1017079A5 (nl) * 2006-03-27 2008-02-05 Tapijteenheid en tapijtrandrofielen voor het vormen van dergelijke tapijteenheid.
JP2019525783A (ja) * 2016-06-09 2019-09-12 シームレス・アテニュエイティング・テクノロジーズ・インコーポレーテッド 弾性のある表面下構造を有する衝撃吸収安全マットシステム
EP3469167A4 (fr) * 2016-06-09 2020-04-15 Seamless Attenuating Technologies, Inc. Tapis de sécurité absorbant les chocs et système de rembourrage avec structure de sous-surface élastomère

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