EP2972060A1 - Light-weight semi-rigid composite anti-ballistic systems with engineered compliance and rate-sensitive impact response - Google Patents

Abstract

Composite anti-ballistic systems comprising multiple nested sub-laminates are disclosed wherein each sub-laminate comprises sub-layers of unidirectional tapes comprising monofilaments made from engineering fibers having anti-ballistic properties embedded in polymer matrix materials. The sub-laminates are nested with interfacial materials such as stiffening polymers or polymer foam engineered for controlled compliance, deformation, energy release, and rate sensitive behavior. Alternating foam and sub-laminate layers are nested to form antiballistic plates that can be flat and/or curved, and can be used alone or incorporated into antiballistic devices.

Description

LIGHT-WEIGHT SEMI-RIGID COMPOSITE ANTI- BALLISTIC SYSTEMS WITH ENGINEERED COMPLIANCE AND RATE-SENSITIVE IMPACT RESPONSE

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 61/780,803, filed March 13, 2013, which is incorporated herein in its entirety. FIELD OF THE INVENTION

[0002] This application relates in general to fiber-reinforced products and in particular to improved composite anti-ballistic systems comprising stacked arrangements of sub-laminates.

BACKGROUND OF THE INVENTION

[0003] Current anti -ballistic personal protection is generally by either common Small Arms Protective Insert (SAPI) armor plates or by conventional soft vests. Rigid ceramic SAPI plates provide effective protection, but they limit mobility and are uncomfortable, which can distract soldiers in the field and induce unnecessary rapid fatigue.

[0004] Additionally, SAPI plates are very susceptible to serious damage due to impacts endemic to a soldier's operations in the field; and the damage is difficult to detect, impossible to repair and can result in serious or total degradation in ballistic protection. SAPI plates also have poor protection against closely-spaced multiple hits.

[0005] Therefore, new anti-ballistic systems are desirable. In particular need are new anti-ballistic personal protection systems that feature controlled rigidity under ballistic impact to provide the necessary functions of anti-penetration, load spreading, impact energy management and shock management.

SUMMARY OF THE INVENTION

[0006] In various embodiments, an improved composite anti-ballistic system is disclosed. More particularly, this disclosure relates to composite anti-ballistic systems comprising composite materials of varying properties. In various embodiments, composite anti-ballistic devices are disclosed. In various embodiments of the present disclosure, an antiballistic system comprises multiple nested sub-laminates manufactured from layers of unidirectional monofilaments.

[0007] In various embodiments of the present disclosure, an antiballistic system comprises engineering fibers having anti-ballistic properties. In various embodiments, an antiballistic system comprises polymer matrix materials and interfacial materials engineered for controlled compliance, deformation, and energy release, along with rate sensitive behavior.

BRIEF DESCRIPTION OF THE DRAWINGS [0008] FIG. 1 shows a diagrammatic view illustrating at least one composite laminate material according to an embodiment of the present disclosure;

[0009] FIG. 2 shows an enlarged detail view of area "A" of FIG. 1 in accordance with the present disclosure;

[0010] FIG. 3 shows a data graph, illustrating percent performance vs. number of layers, in accordance with the present disclosure;

[001 1] FIG. 4 shows a diagrammatic view, illustrating flexibility of at least one panel of such at least one composite laminate material, in accordance with the present disclosure;

[0012] FIG. 5 shows a diagrammatic view, illustrating impact loading of at least one panel of such at least one composite laminate material, in accordance with the present disclosure;

[0013] FIG. 6 shows a diagrammatic view, illustrating a comparative thickness of at least one panel of such at least one composite laminate material, in accordance with the present disclosure;

[0014] FIG. 7 shows a diagrammatic view, illustrating intra-laminar hybridization, in accordance with the present disclosure;

[0015] FIG. 8 shows a diagrammatic view, illustrating comingled filaments, in accordance with the present disclosure; and

[0016] FIG. 9 shows a graphical representation of the change in impact load through use of sub-laminates and interlayers in accordance with various embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION [0017] The following description is of various exemplary embodiments only, and is not intended to limit the scope, applicability or configuration of the present disclosure in any way. Rather, the following description is intended to provide a convenient illustration for implementing various embodiments including the best mode. As will become apparent, various changes may be made in the function and arrangement of the elements described in these embodiments without departing from principles of the present disclosure.

[0018] TABLE 1 provides a glossary of terms and definitions that may be used in various portions of the present disclosure.

TABLE 1 : BRIEF GLOSSARY OF TERMS AND DEFINITIONS

Tow A bundle of continuous filaments.

Ultra-high-molecular- weight polyethylene. A type of polyolefin made

UHMWPE up of extremely long chains of polyethylene. Trade names include

Spectra® and Dyneema®.

Unidirectional tape (or UD tape) - flexible reinforced tapes (also referred to as sheets) having uniformly-dense arrangements of

Unitape reinforcing fibers in parallel alignment and impregnated with an

adhesive resin. UD tapes are typically B-staged and can be used as layers for the composites herein.

[0019] As described in more detail herein below, light-weight semi-rigid composite anti-ballistic systems in accordance with the present disclosure comprise multiple nested sub-laminates. Sublaminates may be manufactured, for example, from layers of unidirectional monofilaments made from engineering fibers with anti-ballistic properties embedded in polymer matrix materials and interfacial materials engineered for controlled compliance, deformation, energy release and rate sensitive behavior.

[0020] In various embodiments, flexibility is gained by splitting the armor up into many sub-laminates that can move independent of each other that may be connected with foam, viscoelastic, static forces, Vanderwall forces, blocking, or rate stiffing materials, or nothing at all.

[0021] In various embodiments of the present disclosure, these layers can be oriented in multiple directions to distribute the impact loads, control deformation and dissipate impact energy to provide ballistic protection in a form that has sufficient, controlled rigidity under ballistic impact to provide the necessary functions of anti-penetration, load spreading, impact energy management and shock management. Such orientation of layers can further provide sufficient flexibility and compliance when worn such that loss of mobility and range of motion is minimized, and wearer comfort is improved. These improvements can enhance combat effectiveness and minimize operator fatigue due to reduced mobility and restriction of range of motion encountered with rigid SAPI plates.

[0022] Although the system according to the present disclosure may be integrated into a system also utilizing a ceramic or metallic component, the pure composite implementation of the system is not susceptible to impact damage like observed in a ceramic SAPI plate and is insensitive to most normal in-service incidental impacts. The system also exhibits superior protection against multiple close spaced hits. Since the system does not absorb significant percentages moisture, the resulting anti-ballistic system does not gain weight or become water-logged due to hydrolysis. The system also is protected from degradation due to flex fatigue, UV radiation and exposure to most agents or chemicals normally encountered.

[0023] In various embodiments, a system in accordance with the present disclosure comprises at least one composite anti-ballistic device. Such at least one composite anti- ballistic device may comprise improved compliance stretchability and flexibility for higher mobility and less range-of-motion-restriction by using at least one multi-layer, multi- directional sublayer construction.

[0024] Such at least one flexible ballistic panel can be made from layers of sub- laminates. The sub-laminates of the panel system can be manufactured from layers of unidirectional monofilaments of engineering fibers having antiballistic properties, a modulus greater than 1.0 x 106 psi and a failure strength in excess of 100,000 psi.

[0025] Such at least one multi-layer, multi-directional sub-laminate approach can use thin (e.g. less than 6 monofilament diameters for conventional monofilaments, less than 0.005" for ultrathin or nano-monofilaments, ropes, yarns, fibers) unidirectional tape ("unitape") layers, or alternatively, intra- or inter-laminar hybridization of filaments. A unidirectional tape is a fiber-reinforced layer having thinly spread parallel monofilaments coated by a resin. In various embodiments, each unitape layer having parallel fibers is inherently directionally oriented, in a dedicated direction, to limit stretch and provide strength in such chosen direction. In various embodiments, a two-direction unitape construction may feature the first unitape layer disposed at a 0° orientation and the second unitape layer disposed at a 90° orientation. In the same manner, various one-direction configurations, two- direction combinations, three-direction combinations, four-direction combinations, and other unitape combinations, may be applied to create laminates having a desired directional or non- directional reinforcement.

[0026] In various embodiments, filaments can comprise various engineering fibers with a Young's Modulus of over 1 msi and an ultimate tensile strength of more than 100 KSI. Such engineering fibers include, but are not limited to: UHMWPE (available under the trade names Dyneema® and Spectra®), Aramid (available under the trade names Kevlar® and Twaron®), PBO fiber under the Zylon® name, liquid crystal polymer Vectran®, glass fibers such as E and S glass, M5 fibers, carbon and para-aramid under the Technora® name. In various embodiments, monofilaments are extruded. [0027] In various embodiments, sub-laminates of the panel system comprise at least two unidirectional tapes, each having extruded monofilaments therein, all of such monofilaments lying in a predetermined direction within the tape, wherein such monofilaments have diameters less than about 60 microns and wherein spacing between individual monofilaments within an adjoining strengthening group of monofilaments is within a gap distance in the range between abutting and/or stacked monofilaments up to about 300 times the monofilament major diameter.

[0028] In various embodiments, sub-laminates further comprise a set of other laminar overlays. In various embodiments, a sub-laminate comprises a first one of such at least two unidirectional tapes includes monofilaments lying in a different predetermined direction than a second one of such at least two unidirectional tapes.

[0029] In various embodiments, a sub-laminate comprises a combination of the different predetermined directions of such at least two unidirectional tapes, and these directions are user-selected to achieve sub-laminate properties having planned directional rigidity/flexibility. Such a user-planned arrangement can provide a sub-laminate comprising a three-dimensionally shaped, flexible composite part. In addition, sub-laminates may comprise multiple laminate segments attached along peripheral joints. In various embodiments, a sub- laminate comprises at least one laminate segment attached along peripheral joints with at least one non-laminate segment. Further, a sub-laminate may comprise multiple laminate segments attached along area joints.

[0030] In various embodiments, a sub-laminate comprises at least one laminate segment attached along area joints with at least one non-laminate segment. In various embodiments, a sub-laminate comprises at least one laminate segment attached along area joints with at least one unitape segment. In various other embodiments, a sub-laminate comprises at least one laminate segment attached along area joints with at least one monofilament segment. In various embodiments, a sub-laminate may comprise at least one rigid element.

[0031] In various embodiments, engineering fibers can further include nano- filaments, nano-ropes, nano-yarns, nano-tows, nano-powder, and/or nano-film that may be incorporated into the unitape layer, associated with the unitape, and/or applied to the outer surface of the unitape. Such at least one nano-material may be applied to the outer surface of individual monofilaments by nano-spray, electron beam deposition, sputtering, vapor deposition, atmospheric plasma deposition, infusion, or as part of polymer coating. Such coating may comprise a cross-linking system with thermal activation, or alternately two-part self-curing, or alternately radiation cured such as E-beam, RF cured, UV cured, or alternatively, heat cured. The surface of the fibers, the surface of the nano-component and/or the polymer resin may all be provided with chemically reactive functional groups that create a strong chemical bond between the monofilament surface, the nano-component, the short fiber component or the resin, to improve adhesion and enhance energy dissipation.

[0032] Individual unitape plies may vary from 1.5-80 g/m2 of areal density. In various embodiments, a unitape can contain one single class of fibers such as Aramid, UHMWPE, glass, and the like, or alternately contain a combination of classes or styles (same class of fiber but different spec for example), or alternately contain any combination of the above, such as in a predetermined pattern or configuration. The different fiber types may be discrete alternating sets of each material across the width or thickness of the unitape or they can be distributed in a uniform intermixed or comingled configuration. These unitapes may be layered to produce any combination of materials within each layer of the sub-laminate. Examples are having a sub-laminate made from only one grade of monofilament in each unitape in the sub-laminate, or by using one or more different unitapes in the sub-laminate wherein each unitape is made from one type of monofilament. Another example is having a unitape made up of hybrid unitape with multiple fiber types incorporated in each layer but having all the unitape in the sub-laminate made from the same specification of hybrid. Yet another example is the most general where the sub-laminate is made from unitapes with multiple mixes of fiber in the unitape and multiple types of unitape used to make up the sub- laminate.

[0033] Individual unitapes within a sub-laminate may be made from differing fiber areal densities. Hybrid sub-laminates of this kind can provide improved ballistic performance when one of the types of fiber may provide superior protection under some conditions but may not provide adequate protection under another set of conditions. A good example would be the use of UHMWPE monofilaments, which provide excellent anti-ballistic protection under most conditions but are limited in their ability to protect against some impacts by incendiary projectiles that exceed temperature limits of the base polymer. Aramid or PBO hybrids can improve the ability of the UHMWPE base laminate to protect against the incendiary projectile due to the higher temperature capabilities of the aramid or PBO monofilaments. Using monofilaments of dissimilar properties can also improve the ballistic impact performance because the interactions of the dissimilar monofilaments can generate significant impact energy absorption, shock dissipation and controlled deformations due to the incompatibility of strains between the dissimilar monofilaments. [0034] In various embodiments, the minimum number of plies within a sub- laminate can be determined by semi-empirical methods that find the approximate number of plies needed to bring the specific ballistic performance of the sheet up to the level most comparable to the monolithic plate case by obtaining the optimum "lamination effect." At a certain number of unitape layers, the improvement in ballistic performance levels off (as illustrated in FIG. 3), and the number of plies is determined by the use of a sub-laminate thickness that provides the degree of flex desired.

[0035] Each unidirectional ply can be oriented in any given in-plane angle. The simplest is a two-direction, cross-ply [0°/90°] configuration, which is easy to fabricate but often does not provide the best ballistic protection or the best resistance to global panel deformation nor to "back wall deformation." Back wall deformation is the area directly under the impact area where the laminate is extruded & pushed back into the body of the wearer, which can cause injury or incapacitation. Excessive deformation also degrades the ballistic protection for multi-hit impacts closely spaced. For this reason it is desirable to have a number of angles selected. Three provide some improvement but four angles spaced at the 0°/45^ο/90^ο/-45° orientations gives the better performance. Some additional improvement can be obtained by adding another set of ply angles such as at 22.5° increments (0 22.5 45 67 90 -67 -45 -22.5 0° for example), or at +/- 30° or +/-60°. The sub- laminates can be made of stacked repeating sets of these ply groups to build up the desired number of unitape layers in order to achieve the required ballistic performance and flexibility.

[0036] In various embodiments, the resin content can range from 1% to 30% of the total areal weight of the unitape with the lower resin contents generally providing better ballistic performance. High and low resin content unitape can be combined in various stacking sequences and layup patterns.

[0037] Thin layers of polymer films, non-wovens, and layers of nano-fibers or films can be located at one or more unitape interfaces to improve or modify ballistic performance.

[0038] Resin materials may comprise epoxy base, cyanate ester base, or polyester based resins of varying molecular weight or composition combined with various curing agents to provide the desired matrix properties. Matrix materials may also be thermoplastic polyurethane, alternately block copolyesters, alternately two part polyurethane either with the aromatic or aliphatic isocyanate curing mechanism, alternately ceramics, alternately E-beam deposition polymers, alternately silicones, or others. Resins may be a hot melt, alternately aqueous solutions, alternately solutions with organic or inorganic solvent, alternately water or solvent dispersions, alternately powders, alternately spun-bonded films, alternately extruded sheets, alternately cast sheets. The cast or extruded sheets may be homopolymer, alternately a multilayer co-extrusion, alternately co-cast onto a carrier, film, paper, or cloth or the film may be unsupported.

[0039] In various embodiments, at least one multilayer, multidirectional sub- laminate can comprise unitape of pultruded monofilaments such as to provide the laminate with a multidirectional-layered network.

[0040] The bending stiffness of a ballistic plate or sheet, neglecting effects of transverse strain, is proportional to the section modulus of the plate or sheet, and may be calculated according to the formula:

Section Modulus = Z = BD²/6 where B is the width and D is the thickness of the plate or sheet.

[0041] For comparison purposes only, the width can be normalized to 1 to determine the effects of the sheet or plate thickness on the flexibility of comparable plates and sheets. One inch is a common thickness for composite sheets because it roughly gives 5 lbs/ft2. For the 1" plate section, the modulus = Z = BD2/6 = (1) (l)/6= 1/6. The effect on flexibility by moving to thinner materials can be calculated, starting at 0.020" and going up in 0.020" increments to 0.10". Z = (1) (1/50)2/6 = 1/ (6) (2500). Therefore, 0.020" = 1/2500 of the bending stiffness of the 1" plate since Z is proportional to the thickness of the panel squared. If t = 0.030, then Z = 1/11 11. If t = 0.040, then Z = (1/25)2.

[0042] For a 1" stack of the 0.020" sheets, the total flex equals the sum of section modulus: Zeff =∑ 2i (Z x 50) 1/2500 * (50) = 1/50; and 1=1 to 33.3; Zeff =∑ 2i = 1/33.3. As seen from this pattern, the flexibility of a panel made up of sub-laminates of equalizing total thickness, if all sub-laminate thicknesses are the same proportion using this relationship, the total desired panel thickness can be broken down into a number of sub-laminates that provide the necessary increase in flexibility. If a thickness of 0.020" is chosen for the sub-laminate sheet, then the effective stiffness is 1/50 times lower since the bending stiffness of the stack of 50 0.020" sub-laminates is 50 times less than a monolithic 1" ballistic plate.

[0043] If engineered properly, a panel made from sub-laminates may have performance ranging from minimal reduction in ballistic performance to actually being higher in ballistic protection than solid rigid plates, while still being flexible. The sub- laminate may be used as discrete sheets with maximum flexibility or they may be lightly bonded together with a thin layer of compliant rate-sensitive dilation material embedded in compliant foam.

[0044] Bonding the sub-laminate together in such a way decreases the flexibility of the panel but may still allow for a compliant panel, especially if the panel does not need to undergo large deformations as is the case with ballistic plates. In various embodiments, a ballistic plate should impart just enough "give" into the panel to provide the necessary level of mobility and comfort. This is a subjective parameter that depends upon the total thickness of the ballistic panel system, the properties of the monofilament in the sub-laminate and the degree of compliance engineered at the interfaces between the laminates.

[0045] Although the sub-laminate system has sub-engineered flexural properties, much of the flexibility is due to the low shear and Young's modulus of the viscoelastic dilatory foam materials at the interface, bonding the sub-laminate panels into a single panel. Dilatory materials are very rate-sensitive and undergo a transition from highly compliant elastomeric material to highly rigid, solid material. Under impact, the rate of sensitive dilatory layers converts from a soft compliant material into a stiff interlayer that locks up the sub-laminates together so that they act as a solid panel, which means that impact stiffness of a panel increases to close to that of a solid ballistic panel.

[0046] The rigidness of the panel under impact spreads the impact loads and maintains the structural integrity of the panel during the impact. Since this is a viscoelastic effect, the rate at which the interlayers transform from soft to rigid can be controlled to manage the impact and spread the force of the impact event over a longer period of time. Spreading the impact load over a longer time period reduces the magnitude of the impact loads, and the load rate can be adjusted to provide optimal load transfer to the individual sub- laminates to provide the highest level of protection from each individual ballistic sub- laminate.

[0047] With reference now to FIG. 1, an embodiment of a antiballistic panel 100 is illustrated in cross-section. The panel comprises compliant, viscoelastic interlinear layers of rate-sensitive, higher rate stiffening polymer and polymer foam, between layers of composite sub-lamina. A section of the panel 100, labeled "A," is magnified in FIG. 2 to more clearly show an embodiment comprising alternating layers of flexible composite sub-laminate and stiffening polymer or polymer foam.

[0048] FIG. 4 is a diagrammatic illustration of the flexibility of panel 100 under normal use due to the layering of flexible sub-laminates. [0049] FIG. 5 illustrates the resistance of the panel 100 to an impact force (e.g. from the triangular projectile illustrated). Under impact loads, the rate-sensitive interlace rigidizes or "freezes" the plate 100 into the equivalent of one-piece panel with no sub- laminate structure.

[0050] At least one area of design flexibility on the sub-laminate panels is the ability to select the thickness of the viscoelastic, dilation interlayers. The most effective of the commercial systems are in the form of lightweight foams that allow for the incorporation of relative thick layers with minimal weight increase. The flexibility of the panel is enhanced in the case of thicker compliant layers, which is derivable from a mobility and comfort perspective. Use of thicker compliant layers also increases the thickness of the global panel system. This thickness increase by itself does not generally limit mobility or restrict motion since flexibility is actually enhanced. This increased thickness does significantly increase the effective section modulus of the global panel system during the transient rigid state under impact, which can significantly increase the "effective stiffness" of the rigid panel.

[0051] With reference now to FIG. 6, a single 1" thick monolithic panel is broken up into 4 sub-laminates with viscoelastic layers there between, bringing total thickness of the new panel constructed from sub-laminates to 1.5." In this case, the Section Moduli (SM) of the 1" monolithic plate, and that of the 1.5" thick sub-laminate plate, are determined by the formulas:

Section Modulus = (l)²/6 for monolithic

Section Modulus = (1.5)²/6 for sub-laminate plate

SM I _mono = 1/6 SM I _sub = 2.25/6

[0052] The demonstration summarized in FIG. 6 and calculated hereinabove show that the effective stiffness of the rigid sub-laminate panel under impact has 2.25 times the stiffness and resistance to deformation as the monolithic plate. Thus, with only a 50% increase in thickness, 2.25 times the stiffness and resistance to deformation is achievable.

[0053] The "rigidized" compliance layer can act as a core material under impact to improve the structural properties of panel system globally. The viscoelastic layers can also be engineered to provide some progression of load transfer into the individual sub-laminates as the impact event progresses through the panel system, which can improve load spread, energy management and contribute to enhanced anti-penetration.

[0054] Additionally, engineered viscoelastic dilation layers in accordance with the present disclosure provide improved anti-ballistic properties, and improved flexibility for better mobility and increased range of motion without adding excessive weight and/or bulk. This rigidizing or "freezing" behavior under impact load can provide and one or combination of benefits, including: (1) distributing the impact loads, to spread them within the assembly reducing maximum peak loads and associated injury; (2) restricting deformation of the panel in the out-of-plane direction, thus reducing "back wall deformation" that is a measure of how much the panel is deflected inward towards the body of the wearer; (3) increasing the area of the panel used to resist the impact for better energy absorption and shock dissipation; and, (4) allowing improved resistance to projectile penetration by optimizing the progressive response of the panel system to the projectile as it strikes and enters the panel.

[0055] In various embodiments, the sub-laminas can comprise hybridization of fiber types. For example, hybridization can be inter-laminar (e.g. different ballistic fiber types, layer by layer). As illustrated in FIG. 7, hybridization of fiber types can be intra- laminar hybridization (e.g. one or more different fiber types within a single layer, laid out in accordance to a predetermined pattern or design). As illustrated in FIG. 8, hybridization of fiber types can comprise a comingling of fibers, (e.g. two or more fiber types generally mixed uniformly at the monofilament level).

[0056] The system can alternatively comprise hybridization via different fiber types (e.g., DyneemaTM and Kevlar). In various embodiments, the system can comprise hybridization via different styles, alternately different product forms, alternately different mechanical properties of the same or similar fiber or monofilament (i.e. Dyneema SK 76 hybridized with Dyneema SK90, or Zylon HM hybridized with lower modulus Zylon). This approach can be useful when significant improvements in one fiber type are offset by reduction in another critical property.

[0057] For example, some DyneemaTM fibers have been drawn to a very fine filament which improves in-plane response but introduces some other limitations which prevent full realization of the fibers anti-ballistic potential. Larger diameter UHMWPE fibers may have lower properties but their thicker filaments combined with a slightly different microstructure can combine to provide higher overall anti-ballistic performance and protection than either one is capable of independently. The system may feature improvement or optimization of the ballistic performance of the monofilaments, such as by use of fiber surface treatments, surface functionalization, surface coatings, surface grafting and/or deposition with one or more types or layers to optimize the response and integration of the monofilaments to the matrix.

[0058] In various embodiments, the system can further comprise engineered fiber, such as matrix interfacial properties by use of fiber surface treatments, surface functionalization, surface coatings, surface grafting and/or deposition with one or more types or layers to optimize the response and integration of the monofilaments to the matrix.

[0059] In various embodiments, the system can further comprise incorporation of various rate sensitive polymers and/or non-woven composites of various fibers and polymers, such as to produce a rate sensitive system, such as in strategic inter-laminar and intra-laminar locations for matrix and intra-laminar interfaces.

[0060] In various embodiments, the system can further comprise engineered micro flaws in monofilaments, such as to promote optimized localized massive simultaneous microfracture of filaments, such as to take advantage of the inherent high strain energy release rate thresholds related to the high Work-Energy-To-Initiate-Fracture properties combined with the high internal hysteresis associated energy dissipation with post failure relaxation with some anti-ballistic monofilaments such as UHMWPE and M5 fibers.

[0061] In various embodiments, sub-laminates may be made from a single anti- ballistic monofilament, or multiple fibers may be combined to create a hybrid of many types of monofilaments.

[0062] Hybridization may be at the global panel level where sub-laminates are individually manufactured from one type of monofilament but several sub-laminates consisting of different types of monofilament may be used in a desired configuration. At least one non-hybrid sub-laminate (i.e. UHMWPE, Aramid, PBO, glass) along with sub-laminates featuring various forms and/or combinations of fiber classes or hybridization schemes may be used in a configuration.

[0063] All of the sub-laminates in a panel may be made from one single class of fiber such as UHMWPE, Aramid, PBO, Glass, etc. if desired. Panels made this way can be either flat or curved to better fit the wearer. If the panels are curved, the sub-laminates may be formed such that they nest together properly when stacked to form the total laminate plate system.

[0064] In various embodiments, curved sections can be press formed, autoclave formed, and/or laminate formed. Additionally, the curved sections can be fabricated in one set of sub-laminates, or fabricated individually and then assembled. [0065] In various embodiments, under appropriate circumstances, considering such issues as use environment, future technologies, cost, etc., other uses of the composite system, such as, for example, rigid plates made from same materials systems where flexibility is not desired, blast protection, containment of explosive failure of rotating machinery, containment of jet engine and other gas turbine engine compressor blade failures, sporting good protection, crash protection, reinforcement of masonry, brick and concrete structure and buildings to protect them from blast or seismic damages and secondary collapse or failure, vehicle, aircraft armor, use as a flexible "cloth" replacement for conventional ballistic soft vests, etc., may suffice.

[0066] The flexible sub-laminate can make a very high performance option as a replacement for current vest fabrics for flexible vests and body armor. In various embodiments, the composite sub-laminates have superior anti-ballistic properties, and load spreading relative to conventional cloth technologies and having the further advantage that they do not absorb moisture and become liquid saturated, and the fiber monofilaments are fully encapsulated and protected so they are protected from abrasion, chaffing, flex fatigue and environmental degradation due to sweat, fluids, chemicals, and UV or visible radiation.

[0067] In vest applications it is generally advantageous to select the sub-laminate thickness that gives the highest degree of anti-ballistic protection with the thinnest overall laminate thickness, and the maximum number of the thinnest unitapes, such as oriented in as many angular directions as is possible consistent with cost and production throughput constraints. Further, the use of shear thickening matrix and interlaminate layers can be used to improve impact properties.

[0068] A thin, compliant, rate-sensitive layer or layers, about 1-10000 microns in thickness, can be incorporated into the sub-laminate. In various embodiments, this layer may be about 1-100 microns in thickness. In various other embodiments, this layer may be about 1-10 microns in thickness. This layer or layers can be a viscoelastic material with high loss factor for absorbing, damping, and dissipating impact forces and energy release from the impact while also adding flexibility to the sub-laminate. Strategically locating interlayers can substantially enhance load spread and energy management by tailoring the impact impulse as was previously discussed, and as illustrated graphically in FIG. 9.

[0069] Antiballistic composite in accordance with the present disclosure is useful for many aircraft applications since it can be desirable to have a semi-flexible material, for example, in the nacelle armoring the compressor blades of the engine. The flexibility of the armor prevents over-stiffening the nacelle, which could promote premature fatigue of the engine support structure, but has enough rigidity during the impact of the failed compressor blades that it can retain structural integrity while simultaneously containing the blade fragments.

[0070] Antiballistic composite in accordance with the present disclosure is also an ideal solution for reinforcement of masonry brick, concrete structure and buildings to protect them from blast or seismic damages, and secondary collapse or failure by laminating one or more sub-laminate sheets to the walls or ceilings of the structures using an integrated gel style curing adhesive layer or via a sprayed or brushed on toughened adhesive or a combination of both types of bonding agents.

[0071] Antiballistic composite in accordance with the present disclosure can be transparent, opaque, translucent, colored, printed or textured for decorative architectural effects or to add camouflage, IR control or other Low Observable finishes and textures. Additionally, the material can incorporate a weatherable outer surface layer that has an environmental control function such as solar reflectivity or UV blocking for insulation or energy efficiency as a secondary feature.

[0072] It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the spirit or scope of the disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

[0073] Likewise, numerous characteristics and advantages have been set forth in the preceding description, including various alternatives together with details of the structure and function of the devices and/or methods. The disclosure is intended as illustrative only and as such is not intended to be exhaustive. It will be evident to those skilled in the art that various modifications may be made, especially in matters of structure, materials, elements, components, shape, size and arrangement of parts including combinations within the principles of the disclosure, to the full extent indicated by the broad, general meaning of the terms in which the appended claims are expressed. To the extent that these various modifications do not depart from the spirit and scope of the appended claims, they are intended to be encompassed therein

Claims

WE CLAIM:

1. An antiballistic composite comprising:

(a) sub-laminate layers; and

(b) optionally, a high-rate stiffening polymer or polymer foam distributed between said layers.

2. The composite of claim 1, wherein said sub-laminate layers comprise at least one unidirectional tape sub-layer, each of said tape sub-layers comprising parallel monofilaments coated with a resin.

3. The composite of claim 2, wherein said monofilaments have diameters less than about 60 microns and wherein spacing between individual monofilaments within an adjoining strengthening group of monofilaments is within a gap distance in the range between abutting and/or stacked monofilaments up to about 300 times the monofilament major diameter.

4. The composite of claim 2, wherein said monofilaments have modulus greater than 1.0 x 10⁶ psi and failure strength greater than greater than 1.0 x 10⁵.

5. The composite of claim 2, wherein said tape sub-layers total two in number to form a ply group, and wherein the parallel monofilaments within each of said two sub-layers have a relative orientation of 0°/90° between sub-layers.

6. The composite of claim 2, wherein said tape sub-layers total four in number to form a ply group, and wherein the parallel monofilaments within each of said four sub-layers have a relative orientation of 0 45 90 -45° between sub-layers.

7. The composite of claim 2, wherein said tape sub-layers total nine in number to form a ply group, and wherein the parallel monofilaments within each of said nine sub-layers have a relative orientation of 0722.57457677907-677-457-22.570° between sub-layers.

8. The composite of claim 2, wherein said tape sub-layers total any variable in number to form a ply group, and wherein the parallel monofilaments within each of said number of sublayers have any number of relative orientation between sub-layers.

9. The composite of claim 1, wherein said high-rate stiffening polymer or polymer foam is a viscoelastic dilatory foam material.

10. An antiballistic device, comprising at least one anti-ballistic composite according to claim 1.

11. The device of claim 10, comprising multiple composites nested into a plate system.