WO2023230503A1

WO2023230503A1 - Impact attenuating tensile helmet liner

Info

Publication number: WO2023230503A1
Application number: PCT/US2023/067394
Authority: WO
Inventors: John Weber
Original assignee: Gentex Corporation
Priority date: 2022-05-25
Filing date: 2023-05-24
Publication date: 2023-11-30

Abstract

A helmet liner for a helmet shell includes a peripheral wall configured to abut an inner surface of the helmet shell, and a bonnet configured to receive a head of a wearer. The bonnet is coupled to the peripheral wall and configured to be spaced from the inner surface of the helmet shell. The bonnet is configured to undergo tensile deformation in response to an impact event occurring at the helmet shell.

Description

TITLE

[0001] Impact Attenuating Tensile Helmet Liner

CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63/345,502 filed May 25, 2022 entitled “Impact Attenuating Tensile Helmet Liner”, which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

[0003] The present disclosure generally relates to helmet liners and, in some embodiments, to an impact attenuation helmet liner.

SUMMARY

[0004] In one embodiment there is a helmet liner for a helmet shell, the helmet liner including a peripheral wall configured to abut an inner surface of the helmet shell, and a bonnet configured to receive a head of a wearer and coupled to the peripheral wall and configured to be spaced from the inner surface of the helmet shell, the bonnet configured to undergo tensile deformation in response to an impact event occurring at the helmet shell. In some embodiments, the bonnet is a lattice structure defining a plurality of vents. In some embodiments, the lattice structure is a Voronoi tessellation 2D lattice structure. In some embodiments, the lattice structure is an auxetic lattice sheet structure.

[0005] In some embodiments, the helmet liner further includes a plurality of impact attenuation pads coupled to an outer surface of the bonnet. In some embodiments, the helmet liner further includes one or more bellows protruding outwardly from an outer surface of the bonnet. In some embodiments, the helmet liner is custom fit to the contour of a wearer’s head. In some embodiments, the helmet liner is comprised of one or more of: a rigid polyurethane, elastomeric polyurethane, a thermoset polymer, or a combination thereof. In some embodiments, the helmet liner is comprised of one or more of: polyamide, acrylonitrile butadiene styrene (ABS), polycarbonate, poly etherimide (PEI), and polyetherketone (PEEK). In some embodiments, the helmet liner is comprised of glass or carbon fiber reinforced composites. In some embodiments, the bonnet is comprised of a single layer of material. In some embodiments, the helmet liner weighs about 150 grams or less.

[0006] In another embodiment, there is a helmet for impact attenuation, the helmet includes a helmet shell including an inner surface, an outer surface, and a bottom peripheral edge, and a helmet liner. The helmet liner includes a peripheral wall abutting the inner surface of the helmet shell, and a bonnet coupled to the peripheral wall spaced from the inner surface of the helmet shell, the bonnet configured to undergo tensile deformation in response to an impact event occurring at the helmet shell. In some embodiments, the bonnet is a lattice structure defining a plurality of vents. In some embodiments, the lattice structure is a Voronoi tessellation 2D lattice structure. In some embodiments, the lattice structure is comprised of auxetic cells. In some embodiments, the bonnet does not directly contact the helmet shell. In some embodiments, the helmet liner further includes a plurality of impact attenuation pads coupled to an outer surface of the bonnet. In some embodiments, the helmet liner further includes one or more bellows protruding outwardly from an outer surface of the bonnet.

[0007] In another embodiment there is a helmet liner for a helmet shell, the helmet liner includes a peripheral wall configured to abut an inner surface of the helmet shell, and a tensile structure coupled to the peripheral wall and having a Voronoi tessellation 2D lattice structure pattern, the lattice structure comprised of a single layer of material and configured to be spaced from the inner surface of the helmet shell, the lattice structure configured to undergo tensile deformation in response to an impact event occurring at the helmet shell, and the helmet liner weights 150 grams or less.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing summary, as well as the following detailed description of embodiments of the impact attenuating tensile helmet liner, will be better understood when read in conjunction with the appended drawings of exemplary embodiments. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

[0009] In the drawings:

[0010] Fig. l is a top perspective view of a helmet shell having coupled thereto an impact attenuating tensile helmet liner in accordance with an exemplary embodiment of the present invention;

[0011] Fig. 2 is a bottom perspective view of the helmet shell and impact attenuating tensile helmet liner of Fig. 1;

[0012] Fig. 3 is a side cross-sectional view of the helmet shell and impact attenuating tensile helmet liner of Fig. 1 ;

[0013] Fig. 4 is a side cross-sectional illustration of the helmet liner of Fig. 1 in a collapsed state; [0014] Fig. 5 is a side cross-sectional illustration of the helmet liner of Fig. 1 in an expanded state;

[0015] Fig. 6 is a side cross-sectional illustration of a tensile structure of the helmet liner of Fig. 1 in accordance with an embodiment of the present disclosure;

[0016] Fig. 7 is a side cross-sectional illustration of a tensile structure of the helmet liner of Fig. 1 in accordance with another embodiment of the present disclosure;

[0017] Fig. 8 is a side cross-sectional illustration of a tensile structure of the helmet liner of Fig. 1 in accordance with another embodiment of the present disclosure;

[0018] Fig. 9 is an illustration comparing behind armor blunt trauma (BABT) between conventional impact attenuation helmets and a helmet including the impact attenuation tensile helmet liner of Fig. 1;

[0019] Fig. 10 is a perspective view of a helmet liner in accordance with another exemplary embodiment of the present disclosure;

[0020] Fig. 11 is a perspective view of a helmet liner in accordance with another exemplary embodiment of the present disclosure;

[0021] Fig. 12 is a perspective view of a helmet liner in accordance with another exemplary embodiment of the present disclosure;

[0022] Fig. 13 is a perspective view of a portion of a retention system for use with helmet liners of the present disclosure.

DETAILED DESCRIPTION

[0023] Manufacturers of impact attenuation articles, such as helmets, have long dealt with the competing requirements of increasing impact attenuation performance and lowering the overall weight of the helmet and/or impact attenuation article. Helmets, typically have a rigid shell and a compressible liner disposed within the rigid shell. The compressible liner absorbs impact energy and reduces the amount of energy transferred to the user’s head during an impact. Current technologies for impact attenuation materials are typically foam based and have a homogenous impact profile. However, these materials possess inherent performance limitations and often exhibit inconsistent performance over a range of operating temperatures. Due to the temperature dependence of existing liner and impact attenuation materials, the impact performance is limited to the lowest common denominator over the expected operating range. For example, existing liners may have good performance at hot temperatures but poor performance in cold temperatures or vice- versa. The tendency of foam padding to retain moisture and lack breathability, also leads to reduced user comfort during extended use.

[0024] Further, the homogeneity of existing impact attenuation and liner technology often leads to tradeoffs in performance in different regions of the liner. For example, a stiffer foam may be optimal in one area of the helmet, but a softer foam may be optimal in another area of the helmet preventing optimal performance overall. Therefore, there is a need to provide an impact attenuation liner that addresses the above shortcomings of the conventional foam-based impact attenuation liners.

[0025] Referring to the drawings in detail, wherein like reference numerals indicate like elements throughout, there is shown in Figs. 1-9 an impact attenuating tensile helmet liner, generally designated 100, and alternatively referred to as helmet liner 100, in accordance with an exemplary embodiment of the present invention. In some embodiments, the helmet liner 100 is configured to provide topologically optimized impact attenuation over a substantial portion of, or the entirety of, the coverage area of a helmet. In some embodiments, the helmet liner 100 is configured to provide energy absorption capabilities that are greater than what is offered by traditional foams (e.g., Expanded Poly Styrene (EPS), Expanded Poly Propylene (EPP)) while also allowing for customizability of the helmet liner 100. In some embodiments, the helmet liner 100 is configured to be custom fit to the contour of an individual user’s head. In some embodiments, the helmet liner 100 is configured to provide impact attenuation while remaining below a predetermined weight threshold to reduce any strain placed on a wearer’s neck. In some embodiments, the helmet liner 100 includes a plurality of vents such as a lattice structure configured to permit airflow therethrough to prevent hot spots from occurring thereby increasing the comfort of the wearer

[0026] Referring to Figs. 1-3, there is shown a helmet shell 10 and helmet liner 100 of the present disclosure coupled thereto. The helmet liner 100 may be coupled to the helmet shell 10 along a peripheral wall 102 of the helmet liner 100. The peripheral wall 102 of the helmet liner 100 may be configured to abut an inner surface 12 of the helmet shell 10 while the helmet liner 100 is coupled to the helmet shell 10. In some embodiments, the helmet liner 100 is coupled to the helmet shell 10 via one or more fasteners (e.g., screws, bolts, straps, adhesives, or combinations thereof). In some embodiments, the helmet liner 100 is only coupled directly or indirectly to the bottom edge of the helmet shell 10, or proximate thereto. In one embodiment, the peripheral wall 102 of the helmet liner 100 is adhered to an inner surface 12 of the helmet shell 10. In some embodiments, the peripheral wall 102 of the helmet liner 100 may be fixed relative to the helmet shell 10 when coupled thereto. In some embodiments, the helmet liner 100 is coupled to the helmet shell 10 via one or more bolts or screws. For example, the peripheral wall 102 of the helmet liner 100 may include apertures aligned with apertures in the helmet shell 10 such that bolts may pass through each set of apertures to couple the helmet liner 100 to the helmet shell 10 Tn some embodiments, the peripheral wall 102 of the helmet liner 100 is coupled to the inner surface 12 of the helmet shell 10 at four or more different locations (e.g., four screws or bolts spaced from one another proximate the bottom edge of the helmet shell). In some embodiments, the peripheral wall 102 is directly coupled to the inner surface 12 of the helmet shell 10 around all, or nearly all, of the periphery of the helmet shell 10. For example, the peripheral wall 102 may be a continuous band that is directly adhered to the inner surface 12 of the helmet shell 10 along at least a substantial portion (e.g., greater than or equal to 90%) of the peripheral wall 102.

[0027] The helmet shell 10 may be a helmet shell for use in a variety of environments and for various purposes including, but not limited to, adventure activities, sporting, industrial safety, and police or military purposes. In some embodiments, the helmet shell 10 may be any type of head protection helmet shell known in the art. For example, helmet shell 10 may be included in a standard infantry ballistic helmet, an advanced combat helmet (ACH) an enhanced combat helmet 10 (ECH), a modular integrated communications helmet (MICH), a tactical ballistic helmet (TBH), a lightweight marine helmet, police general duty helmet, a personnel armor system for ground troops (PASGT), or an aircrew helmet, such as an HGU-56/P rotary wing helmet or an HGU 55/P fixed wing helmet.

[0028] In some embodiments, the helmet shell 10 is formed of a substrate is generally made of a fiber/resin-based ballistic material. It can be rigid, flexible, or partly rigid and partly flexible. In some embodiments, the substrate or a portion of the substrate is made of a material including ultra-high molecular weight polyethylene (UHMWPE), poly-p-phenylene terephthalamide, aramid, or the like, or any combination thereof. The substrate can be of a single layer or a stack or layup of a composite structure including a plurality of layers/plies of one or more materials. For instance, in an embodiment, the substrate includes a single UHMWPE ply. In an embodiment, a single UHMWPE ply refers to a layer with 2, 3, 4 or more than 4 unidirectional plies tacked together orthogonally. In other embodiments, the substrate is a stack having between 2 and 10 layers/plies, between 10 and 30 layers/plies, between 30 and 100 layers/plies, or more than 100 layers/plies. In some embodiments, the helmet shell 10 is comprised of a composite material including the substrate and one or more coating layers. In some embodiments, the helmet shell 10 has a thickness as measured between the outer and inner surface 12 between about 0.2 inches to about 1.0 inches. In some embodiments, the helmet shell 10 has a thickness as measured between the outer and inner surface 12 between about 0.4 inches to about 1.0 inches. In some embodiments, the helmet shell 10 has a thickness as measured between the outer and inner surface 12 between about 0.4 inches to about 0.8 inches. In some embodiments, the thickness of the helmet shell 10 is about 0.76 inches. In some embodiments, the thickness of the helmet shell 10 is about 0.40 inches. Tn some embodiments, the thickness of the helmet shell is about 0.28 inches.

[0029] Referring to Figs. 2-3 and 13, in some embodiments, the helmet liner 100 is configured to be used with a boltless retention system 20. The helmet liner 100 may be configured to couple the helmet shell 10 to a chinstrap or retention system 20 without the use of fasteners (e.g., bolts, screws) that extend through a thickness of the helmet shell 10. In some embodiments, the retention system 20 may be detachably coupled to the helmet liner 100. For example, the retention system 20 may include one or more fasteners 22 (e.g., as shown in Fig. 13) configured to detachably couple the retention system 20 to the helmet liner 100. In some embodiments, the fasteners 22 of the retention system 20 are bayonet clips. In some embodiments, the helmet liner 100 may include one or more slots 103 that receive strap(s) and/or fasteners 22 of the retention system 20 such that the retention system 20 may be coupled directly to the helmet liner 100. In this manner, the helmet shell 10 may not include any holes and/or openings that would reduce the ballistic integrity of the helmet shell 10 [0030] Referring back to Figs. 1-3, the helmet liner 100 may include a bonnet 104 for receiving a wearer’s head and configured to provide impact attenuation capabilities to the helmet liner 100. The bonnet 104 may define a cavity within which a portion of a wearer’s head may be positioned. The bonnet 104 may be coupled to the peripheral wall 102 of the helmet liner 100. In some embodiments, the bonnet 104 and peripheral wall 102 of the helmet liner 100 are integrally formed. In some embodiments, the helmet liner 100 is manufacturing using an additive manufacturing method (e.g., 3-D printing). Tn some embodiments, the helmet liner 100 is manufactured to be custom fit to a wearer’s head. For example, an inner surface of the peripheral wall 102 and bonnet

104 of the helmet liner 100 may be manufactured to generally match to the contour of an individual user’s head.

[0031] In some embodiments, the helmet liner 100 is configured to suspend the helmet shell 10 above and/or away from a wearer’s head. For example, and as illustrated in Fig. 3, the outer surface

105 of bonnet 104 may be spaced from the inner surface 12 of the helmet shell 10 by an offset distance OD. The offset distance OD may be a distance between the bonnet 104 and the inner surface 12 of the helmet shell 10 while the helmet shell 10 and helmet liner 100 are in a resting state (e.g., in the absence of an impact force exerted on the helmet shell 10). A wearer’s head may abut an inner surface of the bonnet 104, opposite the outer surface 105, thereby spacing the wearer’s head from the inner surface 12 of the helmet shell 10. In some embodiments, the bonnet 104 does not directly contact the helmet shell 10 (e.g., inner surface 12). In some embodiments, only the peripheral wall 102 of the helmet liner 100 directly contact the helmet shell 10 when the helmet liner 100 is coupled thereto. Tn some embodiments, the bonnet 104 may be spaced from the inner surface 12 of the helmet shell 10 by different distances at different locations along the bonnet 104. For example, the offset distance OD of portions of the bonnet 104 closer to the peripheral wall 102 may be lesser than an offset distance OD of portions of the bonnet 104 further from the peripheral wall 102 (e.g., near the top edge of the helmet shell 10). In some embodiments, the maximum offset distance OD is about 2.0 inches. In some embodiments, the minimum offset distance OD is about 0.25 inches. In some embodiments, the minimum offset distance OD is about 0.5 inches. In some embodiments, the offset distance OD is between about 0.25 inches to about 2.0 inches. In some embodiments, the offset distance OD is between about 0.20 inches to about 2.5 inches. In some embodiments, the is an empty air gap between the helmet liner 100 and the helmet shell 12. For example, the space between the bonnet 104 and the inner surface 12 of the helmet shell 10 may be an empty air gap.

[0032] In some embodiments, the helmet liner 100 is configured to provide impact energy absorption via tensile deformation of the helmet liner 100. For example, the bonnet 104 may be configured to deform in a tensile direction in response to an impact experienced at, for example, the outer surface 14 of the helmet shell 10. In some embodiments, the bonnet 104 may undergo tensile deformation rather than compression to help absorb and diffuse the impact energy. In this manner, the bonnet 104 may provide impact attenuation capabilities to the helmet liner 100. In some embodiments, the geometry of the bonnet 104 may be dependent on a desired use case. For example, the specific lattice framework of the bonnet 104 may be altered depending on the desired use case and/or conditions of the helmet shell 10 and helmet liner 100. In some embodiments, the bonnet 104 is configured to provide an amount of impact attenuation sufficient to prevent a wearer from experiencing a traumatic brain injury (TBI) and/or codified in a performance specification. For example, existing methods used to evaluation impact attenuation performance specifications may not be sufficient to predict/prevent TBI, however the helmet liner 100 may be configured to provide an amount of impact attenuation sufficient to prevent TBI.

[0033] In some embodiments, the helmet liner 100 may be configured to allow airflow therethrough to prevent hotspots and improve comfort to a wearer. For example, the bonnet 104 may include a plurality of vents 107 to permit air to flow freely therethrough and around the wearer’s head to prevent or reduce the occurrence of hot spots. In some embodiments, the plurality of vents 107 may be defined by a lattice structure of the bonnet 104. For example, the bonnet 104 may be comprised of a plurality of beams, cables, or truss members connected to one another at nodes and defining vents 107 therebetween. For example, the bonnet 104 may be a lattice structure arranged according to a Voronoi tessellation 2D lattice pattern or another cellular pattern and may be bonded to the inner surface 12 of the bottom edge of the helmet shell 10. In some embodiments, a bonnet 104 having a lattice structure may further improve the venting and absorption/diffusion properties of the helmet liner 100. In other embodiments, the bonnet 104 does not include a lattice structure or vents and is instead a uniform construct devoid of openings extending therethrough.

[0034] In some embodiments, the helmet liner 100 of the present disclosure is configured to prevent or at least reduce the risk of transferring a load to a wearer’s head during an impact event. For example, in conventional helmet liners, an energy attenuating (EA) material (e.g., a foam impact pad) is placed between the wearer’s head and a helmet shell and absorbs impact energy through compressive loading. The offset distance between the wearer’s head and the helmet shell is important to the wearer in terms of comfort and maintaining situational awareness. In the conventional helmet liners, the offset is often wasted because, during compression caused by an impact event, the EA materials may compress to an extent where further compression is not possible without transmitting a significant portion of the load (e.g., from the impact event to the wearer’s head). The phenomenon described in the preceding sentences may be referred to as “bottoming out” and the helmet liner 100 of the present disclosure may be configured to prevent or at least reduce the risk of a bottoming out phenomenon from occurring during an impact event. In some embodiments, the helmet liner 100 includes a single layer or film of material to enable the helmet liner 100 to effectively use 85% or more of the available offset distance OD for energy absorption whereas conventional EA materials (e.g., foam pads) typically are only capable of leveraging less than 70% of available offset effectively.

[0035] The helmet liner 100 may be comprised of a polymer film. In some embodiments, the helmet liner 100 is comprised of a polymer film produced using a thermo-forming process. One or more elements of the helmet liner 100 may be configured to provide impact attenuation over at least a substantial portion of the helmet shell 10. In some instances, the helmet liner 100 may be manufactured via a film forming manufacturing system or method such as vacuum forming. In some embodiments, the helmet liner 100 may include a plurality of tensile elements (e.g., those comprising the bonnet 104) and, in some instances, a plurality of pads 106 (e.g., as shown in Fig. 2). In some embodiments, the pads 106 may be comfort pads configured to abut a wearer’s head when the helmet liner 100 is worn. The pads 106 may be configured to improve the fit and stability of the helmet shell 10 and helmet liner 100, and/or the overall comfort experienced by the wearer. The pads 106 may be positioned between the helmet liner 100 and a wearer’s head when the helmet shell 10 is worn. In some embodiments, one or more fasteners (e.g., hook and loop fasteners) may be coupled to the bonnet 104 and configured to detachably couple the pads 106 thereto. Tn some embodiments, the pads 106 may be configured to provide impact attenuation. For example, the pads 106 may be comprised of a compressible EA material. In some embodiments, the helmet liner 100 may be comprised of a plurality of tensile pads (not shown).

[0036] Referring to Figs. 4-5, the helmet liner 100 may be produced through an additive manufacturing process as dictated by the complexity of the bonnet 104. By producing the helmet liner 100 via an additive manufacturing process, the helmet liner 100 may be produced in an on- demand point of use manufacturing environment and/or reduce waste. It should be understood though that any suitable manufacturing method known to those skilled in the art may be used to produce the helmet liner 100. In some embodiments, the helmet liner 100 may be manufactured in a collapsed state (illustrated in Fig. 2A) and expanded to an expanded state upon installation into a helmet (illustrated in Fig. 2B). In some embodiments, by manufacturing the liner in the collapsed state, there may be a reduction in an additive manufacturing build volume, traditional manufacturing tool sizes, and/or required storage space.

[0037] Referring to Figs. 6-8, in some embodiments, behavior of the helmet liner 100 may be controlled by employing engineered structures such as a lattice, as discussed above. For example, there is shown in Figs. 6-8 there are helmet liners 100’, 100”, and 100’” each having a corresponding bonnets 104a-104c having different lattice frameworks, also referred to as lattice structures. The helmet liners 100’, 100”, and 100’” may be generally the same as helmet liner 100 except for the lattice structure of the bonnets 104a-104c respectively. The lattice structures may be comprised of a two-dimensional lattice sheet or a lattice truss structure having any number of through thickness cells. In some embodiments, the lattice structures may each be configured to attenuate impact energy primarily through tensile loads. In some embodiments, the lattice structures may include one through thickness layer (e.g., as shown in bonnet 104a) or more than one through thickness layer (e.g., as shown in bonnet 104b). In some embodiments, the bonnet 104c may include an auxetic lattice sheet structure configured to, while undergoing tensile loading, expand in thickness thereby automatically increasing offset distance OD (shown in Fig. 3) in response to impact events. In some embodiments, the material that the helmet liner 100 is comprised of may be dependent upon the design of the lattice structure, material properties, and/or desired performance. In other embodiments, instead of a lattice, the helmet liner 100 may be a solid liner with no openings or lattice structure. In some embodiment, the solid liner may include a plurality of vents. [0038] Referring back to Figs. 1-3, in some embodiments, the helmet liner 100 may be custom fit to the contour of the inner surface 12 of the helmet shell 10 or the wearer’s head. For example, the helmet liner 100 (e g., the bonnet 104) may define a surface matching the contour of the inner surface 12 of the helmet shell 10 or the outer surface of a wearer’s head, which may be determined based on a custom scan or other measurement of the wearer’s head. By providing a helmet liner 100 custom fit to the wearer’s head and/or the inner surface 12 of the helmet shell 10, the helmet liner 100 of the present disclosure may not include discontinuities that are prevalent in traditional discreet impact pads, which can cause discomfort or hot spots when worn for extended periods of time. The custom fit of the helmet liner 100 may also increase the stability of the helmet shell 10 and helmet liner 100 when worn in conjunction with external accessories such as, but not limited to, night vision goggles (NVGs), lights, strobes, and NVG counterweights. In some embodiments, the helmet liner 100 may include one more layers or covers that partially or completely cover the bonnet 104a- 14c. The covers may include comfort pads or padding and/or may be configured to couple the pads 106 thereto. In some embodiments, the cover may be a fabric cover that encloses the helmet liner 100.

[0039] Referring to Fig. 9, and as discussed above, the helmet liner 100 of the present disclosure may be configured to provide improved impact attenuation during an impact event than conventional impact attenuation helmet articles. The helmet liner 100 is attached to the helmet shell 10 along a bottom edge and/or periphery of the helmet shell 10, however the bonnet 104 is spaced from the helmet shell 10. By coupling the helmet liner 100 to a periphery of the helmet shell 10 such that the bonnet 104 is spaced from an inner surface 12 of the helmet shell 10 the wearer’s head may be spaced from the helmet shell 10. As such, the wearer’s head may not directly contact the inner surface 12 of the helmet shell 10. By spacing the wearer’s head from the inner surface 12 of the helmet shell 10, the helmet liner 100 of the present disclosure may be advantageous in ballistic and blast threat environments. For example, impacts to the helmet shell 10 may cause the helmet shell 10 to deform and exert a tensile force on the helmet liner 100 that resists the deformation and dissipates and absorbs the impact energy. Furthermore, the helmet liner 100 may space the user’s head from the helmet shell 10 thereby providing space (e.g., the offset distance OD) for the helmet shell 10 to deform and prevent, or at least reduce, a direct energy transfer to the user’s head, particularly during projectile impacts.

[0040] For example, during ballistic events (e g., a projectile resulting in a ballistic impact on the helmet shell 10) the helmet shell 10 may deform significantly in the area directly adjacent to the projectile. Such impacts, when experienced using conventional helmet and/or helmet liner systems often leads to behind armor blunt trauma (BABT) injuries where the projectile is stopped but the helmet shell deforms enough to still injure the wearer. In traditional compression pad systems, the pads transmit the ballistic force to the head, exacerbating BABT as illustrated in Fig. 9 on the left. As illustrated in Fig. 9 on the right, a helmet shell (e.g., helmet shell 10) including the helmet liner 100 of the present disclosure that provides space devoid of any impact padding allows for helmet shell deformation to take place without impinging on the wearer’s head. As can be seen in the comparison of BABT in Fig. 9 the helmet with standard pads (left) experiences greater BABT than and the helmet including the helmet liner 100 of the present disclosure (right). The helmet liner 100 of the present disclosure may space the wearer’s head from a helmet shell 10, which may reduce the direct transmission of blast waves to the wearer.

[0041] The helmet liner 100 may weigh about 100 g as compared to an 80 g weight of a combined EPP liner and retention hardware. Table 1 below includes performance measurements of the helmet liner 100 of the present disclosure in comparison to conventional EPP pads used in conventional helmet liner systems and structures. The measurements included in Table 1 were obtained with a helmet liner 100 that was additively manufactured using an HP Multijet Fusion printer using a Nylon 12 material. It will be understood that optimization of the helmet liner material and geometry will further improve blunt impact performance and reduce weight relative to conventional foam impact pads. In some embodiments, the helmet liner 100 may be comprised of a nylon polymer or an equivalent thereof.

Table 1 : Comparison of impact performance between tensile liner and legacy product at 14 ft/s showing significantly better impact performance from the tensile liner.

[0042] In one embodiment, the helmet liner 100 is comprised of polyurethane. In some embodiments, the helmet liner 100 may be comprised of generally rigid polyurethane. In some embodiments, a generally rigid material refers to a non-elastic or inelastic material having little to no elasticity (e.g., a material having a Young’s modulus greater than about 100 GPa). The helmet liner 100 may be comprised of a generally rigid material, such as polyurethane, such that, the bonnet 104 is permanently crushed when deformed. In some embodiments, helmet liner 100 is comprised of a material configured to deform non-elastically. In some embodiments, helmet liner 100 may include both elastic material and non-elastic material. For example, helmet liner 100 may include a layer of elastic material and a layer of non-elastic material. In some embodiments, helmet liner 100 may include one or more layers of polyurethane.

[0043] In some embodiments, the helmet liner 100 is at least partially comprised of polymeric segments. Helmet liner 100 may be comprised of one or more of polyurethane, polyamide, glass reinforced composites, carbon reinforced composites, thermoplastic polymer such as acrylonitrile butadiene styrene (ABS), polycarbonate, poly etherimide (PEI), poly etheretherketone (PEEK), thermoset polymer such as acrylic polyurethanes, methacrylic polyurethanes, polyurea, polyacrylates, polymethacrylates and poly epoxides. Helmet liner 100, in some embodiments, may also be comprised of one or more of metallic or ceramic materials. In some embodiments, the helmet liner 100 is comprised of a material having a high specific modulus and that exhibits significant toughness. The helmet liner 100 may be comprised of materials such as, but not limited to, rigid polymers with elastomers having a low specific moduli. In one embodiment, the helmet liner 100 may be comprised of a material having an elastic modulus greater than or equal to about 750 MPa. In some instances, the material may have an elastic modulus between about 750 MPa and 100 GPa. In one embodiment, the strain at failure (e.g., non-impact attenuation) is greater than approximately 40%. For example, bonnet 104 may begin to fail when it is strained/elongated to greater than approximately 40% of its size.

[0044] Referring to Fig. 10, in some embodiments there is a helmet liner, generally designated 200, in accordance with another exemplary embodiment of the present disclosure. The helmet liner 200 may be generally the same as helmet liner 100, discussed above, except that the helmet liner 200 may include one or more additional impact attenuation features. For example, the helmet liner 200 may include one or more impact attenuation pads 210 coupled to the outer surface 205 of the bonnet 204 at predetermined locations. In some embodiments, there are a plurality of impact attenuation pads 210 coupled to the bonnet 204. The impact attenuation pads 210 may be comprised of any known EA material. In some embodiments, the impact attenuation pads 210 are positioned along the helmet liner 100 to maximize energy attenuation capabilities in targeted areas. In some embodiments, the impact attenuation pads 210 are coupled to the helmet liner 200 such that the pads 210 are positioned between the bonnet 204 and a helmet shell when the helmet liner 200 is coupled thereto. In some embodiments, the impact attenuation pads 210 are configured to not directly contact the helmet shell. In other embodiments, the impact attenuation pads 210 may directly contact the helmet shell. The helmet liner 200 may also be different from helmet liner 100 in that helmet liner 200 may not include any vents (e.g., vents 107) in the bonnet 204. For example, the bonnet 204 may be devoid of any vents or apertures extending through the thickness of the bonnet 204.

[0045] Referring to Fig. 11, in some embodiments there is a helmet liner, generally designated 300, in accordance with another exemplary embodiment of the present disclosure. The helmet liner 300 may be generally the same as helmet liner 200, except that the bonnet 304 of helmet liner 300 may include vents 307 for providing improved airflow around a wearer’s head when compared to helmet liner 200. The bonnet 304 may be a lattice structure formed of methods known to those skilled in the art. For example, in some embodiments, the bonnet 304 may be formed via a finishing process that removes portions of the polymer film of a solid bonnet structure (e.g., bonnet 204). In some embodiments, bonnet 304 is formed by positioning bonnet 204 within a film punching device to produce bonnet 304 having a lattice structure including a plurality of vents 307. The position, number, and/or size of the vents 307 may be adjusted as desired to to tailor the impact response, reduce weight, and/or improve airflow of the helmet liner 300. In some embodiments the helmet liner 300 may include impact attenuation pads 310 coupled to the outer surface 305 of the bonnet 304 generally the same as pads 210 discussed above. In some embodiments, the impact attenuation pads 310 may be positioned along the outer surface 305 of the bonnet 304 such that they do not overlap any vents 307 of the bonnet 304.

[0046] Referring to Fig. 12, in some embodiments there is a helmet liner, generally designated 400, in accordance with another exemplary embodiment of the present disclosure. The helmet liner 400 may be generally the same as helmet liner 300 except that it may include impact energy absorption features other than impact attenuation pads 310. For example, the helmet liner 400 may include bellows 410 that protrude outwardly from the bonnet 404. In some embodiments, the bellows 410 may be positioned along the outer surface 405 of the bonnet 404 such that they do not overlap any vents 407 of the bonnet 404. The bellows 410 may include opposed sidewalls 41 la- 41 lb protruding outwardly from the bonnet 404 and an outer surface 412 extending between the opposed sidewalls. In some embodiments, the shape of the sidewalls 41 la-41 lb may enable the bellows to be crushed in response to an impact event thereby absorbing energy from the impact event. For example, sidewalls 41 la-41 lb may have a wave-like shape that includes a series of convex and concave curvatures connecting to one another at inflection points therebetween. The bellows 410 may be configured to provide additional impact energy absorption in combination with the bonnet 404. For example, the bellows 410 may be configured to crush proximate the bottom peripheral edge of a helmet shell during an impact event (e.g., a ballistic impact event). The bellows 410 may enable the helmet liner 400 to provide adequate impact attenuation in response to impact events of varying energy levels more efficiently. In some embodiments, the bellows 410 may be dimples or another suitable protruding feature.

[0047] The term “about” or “approximately” is used herein to provide literal support for the exact number that it precedes, as well as a number that is near to or approximately the number that the term precedes. In determining whether a number is near to or approximately a specifically recited number, the near or approximating unrecited number may be a number, which, in the context in which it is presented, provides the substantial equivalent of the specifically recited number. It should be appreciated that all numerical values and ranges disclosed herein are approximate values and ranges, whether “about” is used in conjunction therewith. It should also be appreciated that the term “about,” as used herein, in conjunction with a numeral refers to a value that may be ±0.01% (inclusive), ±0.1% (inclusive), ±0.5% (inclusive), ±1% (inclusive) of that numeral, ±2% (inclusive) of that numeral, ±3% (inclusive) of that numeral, ±5% (inclusive) of that numeral, ±10% (inclusive) of that numeral, or ±1 % (inclusive) of that numeral. It should further be appreciated that when a numerical range is disclosed herein, any numerical value falling within the range is also specifically disclosed.

[0048] It will be appreciated by those skilled in the art that changes could be made to the exemplary embodiments shown and described above without departing from the broad inventive concepts thereof. It is to be understood that the embodiments and claims disclosed herein are not limited in their application to the details of construction and arrangement of the components set forth in the description and illustrated in the drawings. Rather, the description and the drawings provide examples of the embodiments envisioned The embodiments and claims disclosed herein are further capable of other embodiments and of being practiced and carried out in various ways.

[0049] Specific features of the exemplary embodiments may or may not be part of the claimed invention and various features of the disclosed embodiments may be combined. Unless specifically set forth herein, the terms “a”, “an” and “the” are not limited to one element but instead should be read as meaning “at least one”. Finally, unless specifically set forth herein, a disclosed or claimed method should not be limited to the performance of their steps in the order written, and one skilled in the art can readily appreciate that the steps may be performed in any practical order.

Claims

CLAIMS What is claimed is:

1. A helmet liner for a helmet shell, the helmet liner comprising: a peripheral wall configured to abut an inner surface of the helmet shell; and a bonnet configured to receive a head of a wearer and coupled to the peripheral wall and configured to be spaced from the inner surface of the helmet shell, the bonnet configured to undergo tensile deformation in response to an impact event occurring at the helmet shell.

2. The helmet liner of claim 1, wherein the bonnet is a lattice structure defining a plurality of vents.

3. The helmet liner of claim 2, wherein the lattice structure is a Voronoi tessellation 2D lattice structure.

4. The helmet liner of claim 2, wherein the lattice structure is an auxetic lattice sheet structure.

5. The helmet liner of claim 1 further comprising: a plurality of impact attenuation pads coupled to an outer surface of the bonnet.

6. The helmet liner of claim 1 further comprising: one or more bellows protruding outwardly from an outer surface of the bonnet.

7. The helmet liner of claim 1, wherein the helmet liner is custom fit to the contour of a wearer’s head.

8. The helmet liner of claim 1, wherein the helmet liner is comprised of one or more of: a rigid polyurethane, elastomeric polyurethane, a thermoset polymer, or a combination thereof.

9. The helmet liner of claim 1, wherein the helmet liner is comprised of one or more of: polyamide, acrylonitrile butadiene styrene (ABS), polycarbonate, poly etherimide (PEI), and polyetherketone (PEEK).

10. The helmet liner of claim 1, wherein the helmet liner is comprised of glass or carbon fiber reinforced composites.

11. The helmet liner of claim 1, wherein the bonnet is comprised of a single layer of material.

12. The helmet liner of claim 1, wherein the helmet liner weighs about 150 grams or less.

13. The helmet liner of claim 1, wherein the helmet liner is comprised of a material having an elastic modulus of between about 0.75 GPa to about 100 GPa.

14. A helmet for impact attenuation, the helmet comprising: a helmet shell including a material including ultra-high molecular weight polyethylene (UHMWPE), an inner surface, an outer surface, and a bottom peripheral edge; and a helmet liner comprising: a peripheral wall abutting the inner surface of the helmet shell; and a bonnet coupled to the peripheral wall and spaced from the inner surface of the helmet shell by an offset distance of between about 0.25 inches to about 2.0 inches.

15. The helmet of claim 14, wherein the bonnet is a lattice structure defining a plurality of vents.

16. The helmet of claim 15, wherein the lattice structure is a Voronoi tessellation 2D lattice structure.

17. The helmet of claim 15, wherein the lattice structure is comprised of auxetic cells.

18. The helmet of claim 14, wherein the bonnet is configured to undergo tensile deformation in response to an impact event occurring at the helmet shell.

19. The helmet of claim 14, wherein the helmet liner further includes a plurality of impact attenuation pads coupled to an outer surface of the bonnet and positioned between the helmet liner and the helmet shell.

20. The helmet of claim 14, wherein the helmet liner further includes one or more bellows protruding outwardly from an outer surface of the bonnet.

21. A helmet liner for a helmet shell, the helmet liner comprising: a peripheral wall configured to abut an inner surface of the helmet shell; and a tensile structure coupled to the peripheral wall and having a Voronoi tessellation 2D lattice structure pattern, the lattice structure comprised of a single layer of material and configured to be spaced from the inner surface of the helmet shell, the lattice structure configured to undergo tensile deformation in response to an impact event occurring at the helmet shell, wherein the helmet liner weighs 150 grams or less.