Safety helmet with impact resistant material

Abstract

A safety helmet comprising a housing, a linear impact absorbing material, and a rotary impact absorbing material, the safety helmet constructed from a material designed to provide protection to a wearer under extreme environmental conditions and impacts. In one embodiment, the rotational impact absorbing material is formed from a strain rate sensitive material, where the stiffness of the material increases when subjected to an impact.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of and priority to U.S. Provisional Application No. 63 / 374,988, filed on September 8, 2022, which is incorporated herein by reference in its entirety. Background Art

[0003] The present invention relates generally to the field of protective equipment. In particular, the present invention relates to various structures / work helmet designs constructed with materials that provide additional protection to the user's head from impacts that may otherwise impart harmful rotational acceleration to the wearer's head (i.e., rotational impacts and / or combinations of linear and rotational impacts). Summary of the invention

[0004] One embodiment of the present invention relates to a protective work helmet. The protective work helmet includes an outer shell. The outer shell includes an outer surface, an inner surface defining a cavity, and a crown portion, wherein the cavity is sized to receive a user's head. The crown portion is configured to cover a portion of the user's head. A bottom section of the crown portion defines a lower circumference extending along the outer surface of the outer shell. The outer shell also includes a brim extending radially outward from a portion of the lower circumference, and a front mounting ridge. The front mounting ridge is configured to connect an accessory to the protective work helmet. The protective work helmet also includes a linear impact absorbing material located within the outer shell and a rotational impact absorbing material located within the outer shell. The rotational impact absorbing material is a strain rate sensitive material, wherein the stiffness of the rotational impact absorbing material increases when impacted.

[0005] Another embodiment of the present invention relates to a protective work helmet. The protective work helmet includes an outer shell formed of a rigid material. The outer shell includes an outer surface, an inner surface defining a cavity, and a crown portion, wherein the cavity is sized to receive a user's head. The crown portion is configured to cover a portion of the user's head. A bottom section of the crown portion defines a lower circumference extending along the outer surface of the outer shell. The outer shell also includes a brim extending radially outward from a portion of the lower circumference. The protective work helmet also includes a polymer foam insert located within the outer shell and having a certain thickness. The polymer foam insert includes an outer surface facing the inner surface of the outer shell and an inner surface facing the interior. The protective work helmet includes a rotational impact absorbing liner coupled to the inner surface of the polymer foam insert. The rotational impact absorbing liner is a strain rate sensitive material, wherein the stiffness of the rotational impact absorbing liner increases when impacted.

[0006] Another embodiment of the present invention relates to a protective work helmet. The protective work helmet includes an outer shell. The outer shell includes an outer surface, an inner surface defining a cavity, and a crown portion, wherein the cavity is sized to receive a user's head. The crown portion is configured to cover a portion of the user's head. A bottom section of the crown portion defines a lower circumference extending along the outer surface of the outer shell. The outer shell also includes a brim extending radially outward from a portion of the lower circumference, and a front mounting ridge. The front mounting ridge is configured to connect an accessory to the protective work helmet. The protective helmet also includes an impact absorbing insert. The impact absorbing insert includes a linear impact absorbing material positioned within the outer shell and a rotational impact absorbing material positioned within the outer shell. The impact absorbing insert is configured to provide a peak rotational acceleration less than the maximum peak rotational acceleration under the Rheon test method. In a specific embodiment, the impact absorbing insert is configured to provide less than 7000 radians / second under the Rheon test method. 2 The peak rotational acceleration.

[0007] Another embodiment of the present invention relates to a protective work helmet. The protective work helmet includes an outer shell. The outer shell includes an outer surface, an inner surface defining a cavity, and a crown portion, wherein the cavity is sized to receive a user's head. The crown portion is configured to cover a portion of the user's head. A bottom section of the crown portion defines a lower circumference extending along the outer surface of the outer shell. The outer shell also includes a brim extending radially outward from a portion of the lower circumference, and a front mounting ridge. The front mounting ridge is configured to connect an accessory to the protective work helmet. The protective helmet also includes an impact absorbing insert. The impact absorbing insert includes a linear impact absorbing material positioned within the outer shell and a rotational impact absorbing material positioned within the outer shell. The impact absorbing insert is configured to provide a peak rotational acceleration less than the maximum peak rotational acceleration under the Virginia Tech test method. In a specific embodiment, the impact absorbing insert is configured to provide less than 5500 radians / second under the Virginia Tech test method. 2 In such an embodiment, the peak rotational acceleration is greater than 4000 radians per second under the Virginia Tech test method. 2 .

[0008] Another embodiment of the present invention relates to a protective work helmet. The protective work helmet includes an outer shell. The outer shell includes an outer surface, an inner surface defining a cavity, and a crown portion, wherein the cavity is sized to receive a user's head. The crown portion is configured to cover a portion of the user's head. A bottom section of the crown portion defines a lower circumference extending along the outer surface of the outer shell. The outer shell also includes a brim extending radially outward from a portion of the lower circumference, and a front mounting ridge. The front mounting ridge is configured to connect an accessory to the protective work helmet. The protective helmet also includes an impact absorbing insert. The impact absorbing insert includes a linear impact absorbing material positioned within the outer shell and a rotational impact absorbing material positioned within the outer shell. The impact absorbing insert is configured to provide a peak rotational acceleration less than the maximum peak rotational acceleration under the Rheon test method. In a specific embodiment, the impact absorbing insert is configured to provide less than 7000 radians / second under the Rheon test method. 2 The peak rotational acceleration is less than 70 m / s under the Rheon test method. 2 The peak linear acceleration.

[0009] Another embodiment of the present invention relates to a protective work helmet. The protective work helmet includes an outer shell. The outer shell includes an outer surface, an inner surface defining a cavity, and a crown portion, wherein the cavity is sized to receive a user's head. The crown portion is configured to cover a portion of the user's head. A bottom section of the crown portion defines a lower circumference extending along the outer surface of the outer shell. The outer shell also includes a brim extending radially outward from a portion of the lower circumference, and a front mounting ridge. The front mounting ridge is configured to connect an accessory to the protective work helmet. The protective helmet also includes an impact absorbing insert. The impact absorbing insert includes a linear impact absorbing material positioned within the outer shell and a rotational impact absorbing material positioned within the outer shell. The impact absorbing insert is configured to provide a peak rotational acceleration less than a maximum peak rotational acceleration under the Virginia Tech test method. In a specific embodiment, the impact absorbing insert is configured to provide 4000 radians / second under the Virginia Tech test method. 2 and 55000 rad / s 2 and provide a peak rotational acceleration of less than 145 m / s under the Virginia Tech test method 2 The peak linear acceleration.

[0010] Additional features and advantages will be set forth in the following detailed description, and some of these features and advantages will be apparent to those skilled in the art from the description or learned by practicing the embodiments as described in the included written description and the accompanying drawings. It should be understood that both the foregoing general description and the following detailed description are exemplary.

[0011] The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments and together with the description serve to explain principles and operations of the various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present application will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which like reference numerals refer to like elements, wherein:

[0013] Figure 1 is a perspective view of a hard hat positioned on a wearer's head according to an exemplary embodiment.

[0014] Figure 2 According to an exemplary embodiment Figure 1 Exploded view of a hard hat.

[0015] Figure 3 According to an exemplary embodiment Figure 1 A perspective view of a helmet from below with the impact absorbing insert, the suspension system and a portion of the chin strap removed.

[0016] Figure 4 According to an exemplary embodiment Figure 1 A three-dimensional view of a safety helmet viewed from above.

[0017] Figure 5 is a perspective view of a safety helmet according to another exemplary embodiment, as viewed from the rear.

[0018] Figure 6 According to an exemplary embodiment Figure 5 A three-dimensional view of a safety helmet viewed from above.

[0019] Figure 7 is a perspective view of a safety helmet according to another exemplary embodiment, as viewed from above.

[0020] Figure 8 According to an exemplary embodiment Figure 1 Partial cross-sectional view of a safety helmet.

[0021] Fig. 9 The results after testing using the Rheon test method are shown in Figure 2. Figure 1 A graph showing the linear acceleration data of the helmet compared with a sample of conventional helmets.

[0022] Fig.10 is shown after testing using the Virginia Tech test method Figure 1 A graph showing the linear acceleration data of the helmet compared with a sample of conventional helmets.

[0023] Fig.11 is shown after testing using the Virginia Tech test method Figure 1 A graph showing the rotational acceleration data of the helmet compared with a conventional helmet sample.

[0024] Fig.12 is shown after testing using the Rheon test method Figure 1 A graph showing the rotational acceleration data of the helmet compared with a conventional helmet sample.

[0025] Fig.13 After testing using the Rheon test method Figure 1 A graph comparing the injury probability of the hard hat with that of a conventional hard hat sample.

[0026] Fig.14 After testing using the Virginia Tech test method Figure 1 A graph comparing the injury probability of the hard hat with that of a conventional hard hat sample. DETAILED DESCRIPTION

[0027] Referring generally to the accompanying drawings, various embodiments of protective work / construction helmets, shown as hard hats, are shown. The various embodiments of hard hats discussed herein include various designs and materials that provide improved ability to absorb impacts (e.g., falling objects, side impacts of objects, impacts of trips / falls), and are therefore believed to reduce the risk and / or likelihood of head injuries (i.e., concussions, traumatic brain injuries, skull fractures, cuts, bruises, etc.) that workers may suffer on the job site.

[0028] As will be generally understood, many conventional helmets are designed to provide impact protection for specific parts of the head during specific types of impacts. For example, ANSI Type I helmets protect the top of the head, and ANSI Type II helmets are designed to provide top and side impact protection. Many conventional helmets designed to provide rotational acceleration impact protection using structures and / or materials cannot provide comparable performance in terms of linear acceleration absorption. Similarly, many conventional helmets designed to provide linear acceleration absorption using structures and / or materials cannot provide comparable performance in terms of rotational acceleration absorption. The applicant believes that, due to various design requirements for work / construction environments, existing helmet designs cannot provide both high levels of rotational impact protection and / or combined linear and rotational impact performance.

[0029] Applicants believe that the hard hat designs discussed herein provide improved impact protection due to a reduction in peak rotational acceleration, either alone or in combination with linear acceleration, during an impact, thereby reducing the risk and / or likelihood of injury to the hard hat wearer. In various embodiments, a hard hat includes an outer shell and a shock absorbing insert or layer. As will be discussed in more detail below, the shock absorbing insert or layer may include more than one component or material, such as a linear shock absorbing layer in combination with a rotational shock absorbing layer, which reduces rotational acceleration and / or reduces combined linear and rotational acceleration during an impact.

[0030] Applicants believe that the rotational impact absorbing materials described herein that provide rotational impact protection have many advantages over current structures and / or materials used to reduce rotational acceleration within protective helmets. For example, in certain embodiments, the rotational impact absorbing materials are strain rate sensitive materials, wherein the stiffness of the rotational impact absorbing materials increases upon impact. As will be discussed in more detail below, Applicants' test data indicate that the designs discussed herein provide a hard hat with improved rotational impact performance compared to conventional hard hat impact materials that provide rotational energy absorption based solely on material geometry or rely on translation and / or sliding of adjacent impact layers to absorb rotational acceleration.

[0031] In addition to providing improved rotational impact performance, applicants believe that the helmet designs discussed herein also provide a helmet that is potentially reusable after an impact. In various designs discussed herein, the rotational impact absorbing layer absorbs rotational energy in a manner that does not damage the material, and thus results in a helmet that is potentially reusable after an impact, and thus can withstand repeated impacts. Specifically, compared to current protective helmets that have impact materials that plastically deform, resulting in reduced impact performance of such impact materials after a first impact, when the rotational impact absorbing layer is subjected to compression, the rotational impact absorbing material remains within an elastic deformation range.

[0032] In addition, applicants believe that, unlike conventional hard hats that include a Multi-Directional Impact Protection System ("MIPS") for rotational impact protection, the hard hats discussed herein do not require a large sliding plane and / or displacement to absorb impact energy. As will be discussed in more detail below, applicants have found that a hard hat design with a rotational impact layer as discussed herein can reduce the rotational accelerations experienced by a helmet wearer and provide less translational and / or sliding movement of the rotational layer than conventional hard hats with rotational impact protection. Specifically, a hard hat design with a rotational impact layer as discussed herein reduces the rotational accelerations experienced by a helmet wearer and provides less translational and / or sliding movement of the rotational layer than the 10 mm to 15 mm translational or sliding movement allowed by a helmet including a MIPS structure.

[0033] As will be generally understood, many conventional hard hats are designed to comply with various global performance standards (e.g., ANSI standards ANSI Z89.1, EN397, EN14052, EN1292, AS-ANZ 1801, CSAZ94.1, etc.) and wearer requirements that are specific to construction or work environments. These standards and wearer requirements provide requirements that are different from other types of protective helmets (bicycles, football, racing, etc.) that attempt to reduce the impact of rotational impacts on the wearer's head. Due to the extreme environmental conditions (weather, temperature, etc.) that hard hat wearers face, the applicant believes that the hard hat designs discussed herein are able to improve impact performance under a wider range of conditions. For example, the hard hat designs discussed herein are able to improve impact performance up to -30°C, which is a temperature condition that other types of protective helmets are unlikely to face. Similarly, since wearers in work environments often wear hard hats for long periods of time (e.g., most of the workday), design aspects such as weight and comfort are important factors. In addition, the hard hat designs discussed herein also meet various workplace requirements, such as providing mounting locations for accessories used on the job site.

[0034] Reference Figure 1 , shows a perspective view of a protective work or construction helmet, shown as a hard hat 10, according to an exemplary embodiment. The hard hat 10 includes an outer shell 12. In a specific embodiment, the outer shell 12 is formed of a rigid material, such as a rigid polymer material. In various specific embodiments, the outer shell 12 is formed of one of high-density polyethylene (HDPE), acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), polycarbonate / acrylonitrile-butadiene-styrene (PC-ABS), and polypropylene (PP). The outer shell 12 includes an outer surface 14 and an inner surface 16 (see, e.g., Figures 2 to 3 ). The inner surface 16 defines a cavity 18 (see, e.g. Figure 2 ), the cavity 18 is sized to receive the head of a user and / or wearer 20. The shell 12 includes a crown portion 22 and a bottom section 24 that define a lower circumference of the hard hat 10. In various embodiments, a brim 26 extends radially outward from a portion of the lower circumference. In a specific embodiment, the brim 26 extends radially outward from the hard hat 10 and, in particular, the front portion 28 of the shell 12.

[0035] The helmet 10 includes a suspension system 30 and a chin strap 32 to support and secure the helmet 10 to the head of the wearer 20. The shell 12 also includes a plurality of openings or vents 34. The vents 34 extend through the shell 12 to provide fluid communication between the cavity 18 and the ambient air near the outer surface 14 of the shell 12. The shell 12 also includes a recess 25 that is positioned between the front 28 and the rear 68 of the helmet 10 near the ears of the wearer 20 (see, for example, FIG. 1 ). Figure 4 In a specific embodiment, the recess 25 extends a height over a portion of the bottom section 24 proximate to the front 28 and / or rear 68 of the hard hat 10 .

[0036] As will be discussed in more detail below, various embodiments include one or more mounting ridges configured to couple to and / or support a hard hat accessory. A side accessory support ridge or auxiliary mounting ridge 36 is coupled to the lateral side of the shell 12 along the bottom section 24. The auxiliary mounting ridge 36 includes a first end and a second end opposite the first end. A plurality of openings or slots 38 are positioned along the auxiliary mounting ridge 36 between the first end and the second end. The slots 38 are configured to receive a coupling mechanism such as a clip, or a portion of a hard hat accessory, to couple the accessory to the shell 12. The auxiliary mounting ridge 36 supports accessories for the hard hat 10, such as earmuffs, tool or eyeglass holders, light supports, face shields and / or reflectors, and the like.

[0037] In various helmet designs discussed herein, the impact absorbing portion absorbs rotational energy in a manner that does not damage the impact absorbing portion, thereby allowing the helmet to be potentially reusable after an impact and thus able to withstand repeated impacts. For example, when the rotational impact absorbing layer is subjected to compression, the rotational impact absorbing material remains within an elastic deformation range.

[0038] Reference Figure 2 , shows an exploded view of a hard hat 10 according to an exemplary embodiment. The hard hat 10 includes an impact absorbing portion, shown as an impact absorbing insert 40, which is supported within the shell 12 and, in particular, the cavity 18. Generally, the impact absorbing inserts discussed herein include a first portion or layer that provides linear acceleration absorption and a second portion that provides rotational impact absorption. In the specific embodiment shown, the impact absorbing insert 40 includes a first portion, shown as a linear impact absorbing layer 42, and a second portion, shown as a rotational impact absorbing layer or liner 44. In some embodiments, the hard hat 10 includes various padding layers 46 that provide increased comfort to the wearer. In a specific embodiment, the padding 46 is included along the inner surface 16 near the front 28 of the hard hat 10.

[0039] Reference Figure 3 , shows a perspective view from below of a hard hat 10 having a linear impact absorbing layer 42 according to an exemplary embodiment. The linear impact absorbing layer 42 includes an outer surface 48 facing the inner surface 16 of the shell 12 and an inner surface 50 facing inward (i.e., toward the wearer of the hard hat). The rotational impact absorbing liner 44 is coupled to the inner surface 50 of the linear impact absorbing layer 42. The rotational impact absorbing liner 44 includes an outer surface 52 facing the inner surface 50 of the linear impact absorbing layer 42 (see, e.g. Figure 2) and an inner surface 54 facing inward (ie, toward the helmet wearer). In a specific embodiment, the linear impact absorbing layer 42 is formed of a polymer foam material. In a specific embodiment, the linear impact absorbing layer 42 is formed of expanded polystyrene (EPS).

[0040] In various embodiments, the rotational shock absorbing liner 44 is a strain rate sensitive material, meaning that the properties of the rotational shock absorbing liner 44 change at increasing strain rates. Specifically, in such embodiments, the rotational shock absorbing liner 44 is a material in which the stiffness of the rotational shock absorbing material increases under impact. Specifically, the shock absorbing material at a first distance or near the impact location has greater engagement than the shock absorbing material at a second distance or farther from the impact location. Applicants believe that during an impact of compression, shear, or a combination of compression and shear based on the impact location, the entirety of the shock absorbing liner 44 that contacts or engages the user's head is engaged.

[0041] In some embodiments, the rotational shock absorbing liner 44 is a dilatant material (shear thickening material). In various embodiments, the rotational shock absorbing liner 44 includes a plurality of cells. In a specific embodiment, the cells of the shock absorbing liner have anisotropic geometry, so that the material has different responses and behaviors to mechanical deformation in all three directions (X, Y, Z).

[0042] In a specific embodiment, the rotational shock absorbing liner 44 is a unitary piece of polymeric material. In other embodiments, the rotational shock absorbing liner 44 can be formed from multiple pieces of material (i.e., 2 pieces, 3 pieces, etc.). Applicants believe that the unitary rotational shock absorbing liner improves the ease of product assembly, reduces manufacturing costs, provides more consistent performance regardless of the impact location, increases the amount of absorbent storage material within the system (shell 12, linear shock absorbing layer 42, rotational shock absorbing liner 44), and improves sweat management properties.

[0043] As previously mentioned, Applicant believes that unlike the requirements of other types of protective helmets (bicycle, football, racing, etc.) that attempt to reduce the impact of rotational impacts on the wearer's head, the hard hat designs discussed herein are able to improve impact performance over a wider range of conditions (i.e., up to -30°C, most workdays, etc.). In addition, the hard hat designs discussed herein also meet the requirements of various workplaces, such as providing mounting locations (i.e., front side, rear side) for accessories used on the job site.

[0044] Reference Figure 4, shows a perspective view of the hard hat 10 from above according to an exemplary embodiment. Additional side accessory support ridges or auxiliary mounting ridges 36 are coupled to the lateral sides of the shell 12 along the bottom section 24. The hard hat 10 also includes a front mounting ridge 56 positioned on the front 28 of the shell 12. The front mounting ridge includes a right edge 58 protruding outwardly from the front mounting ridge 56 and a left edge 60 opposite the right edge and protruding outwardly from the front mounting ridge 56. In a specific embodiment, the front mounting ridge 56 includes a detent 62 (see, for example, Figure 2 ), the pawl 62 is positioned between the right edge 58 and the left edge 60 and is configured to engage with the accessory mounting bracket 64 (see, for example Figure 1 ) and / or accessories. The right edge 58 and the left edge 60 of the front mounting ridge 56 each extend toward the bottom section 24 of the shell 12. The right edge 58 and the left edge 60 each include a portion that increases in width as the right edge 58 and the left edge 60 approach the bottom section and / or the brim 26.

[0045] In various embodiments, the hard hat 10 includes a second or rear mounting ridge 66 located along the rear 68 of the hard hat 10. This allows a user to attach accessories and / or accessory mounting brackets to both the front 28 and rear 68 of the hard hat 10. The rear mounting ridge 66 is substantially identical to the front mounting ridge 56.

[0046] As will be discussed in more detail below, the helmet 10 is subjected to impact testing. The data collected from the impact testing includes data from multiple impact position points. Specifically, data is collected at the right front position 70, the left side position 72, and the right rear position 74.

[0047] Reference Figures 5 and 6 , a perspective view of a hard hat 100 according to another exemplary embodiment is shown. The hard hat 100 can be used with the impact absorbing insert 40, the suspension system 30, and the chin strap 32. Except for the differences discussed herein, the hard hat 100 is substantially the same as the hard hat 10, and the components of the hard hat 100 are given the same reference numerals plus 100.

[0048] The helmet 100 does not include recesses near the wearer's ears (see, e.g. Figure 1 25 in). Each mounting ridge 156, 166 includes a pair of opposing planar surfaces 176 extending from the crown 122 toward the bottom section 124 of the hard hat 100. A plurality of vents 134 are positioned on the planar surfaces 176. As the planar surfaces 176 approach the bottom section 124, the width of the planar surfaces 176 increases. In addition, the hard hat 100 has a different size and / or shape than the hard hat 10.

[0049] Reference Figure 7, a perspective view of a hard hat 200 according to another exemplary embodiment is shown. The hard hat 200 can be used with the impact absorbing insert 40, the suspension system 30, and the chin strap 32. Except for the differences discussed herein, the hard hat 200 is substantially the same as the hard hat 100, and the components of the hard hat 200 are given the same reference numerals plus 100.

[0050] The brim 226 of the hard hat 200 extends around the entire bottom section 224 (i.e., the brim 226 is a full brim). A rear brim portion 278 of the brim 226 extends radially outward from a portion of the lower circumference of the hard hat 200. In a particular embodiment, the rear brim portion 278 extends radially outward from the rear 268 of the hard hat 200 a greater distance than the brim 226 extends radially from the front 228 of the shell 212.

[0051] As previously mentioned, the hard hat designs discussed herein are designed to provide improved rotational impact performance while meeting wearer requirements (weight, comfort, etc.) unique to a construction or work environment, thereby allowing the user to wear the hard hat for significant periods of time (i.e., most of the workday).

[0052] Reference Figure 8 , schematically illustrates a partial cross-sectional view of a hard hat 10 and an impact absorbing insert 40 located at a crown portion 22 of the hard hat 10. Applicants have determined that the hard hat designs discussed herein achieve improved impact performance. The shell 12 has a thickness T1. In various embodiments, the shell 12 has a maximum wall thickness T1. In various embodiments, the wall thickness T1 is less than the maximum wall thickness.

[0053] In some embodiments, the total weight of the helmet 10 includes the shell, the linear impact absorbing layer 42, and the rotational impact absorbing layer 44. In a specific embodiment, the total weight of the helmet 10 is less than the maximum total weight of the helmet 10. In some embodiments, the total weight of the helmet 10 is less than 20 ounces, and more specifically between about 18.5 ounces and about 15 ounces (i.e., 18.5 ounces plus or minus 0.5 ounces to 15 ounces plus or minus 0.5 ounces). In some embodiments, the total weight of the helmet 10 is between 10 ounces and 20 ounces, and more specifically between 13 ounces and 20 ounces. As will be generally understood, the weight of the helmet 10 is generally less than the weight of a football helmet or a racing helmet, while the weight of the helmet 10 is generally greater than the weight of a bicycle helmet, which generally weighs 10 ounces to 12 ounces.

[0054] In some embodiments, the total weight of the shell 12 is less than the maximum weight. In such embodiments, the hard hat shell has these thicknesses and / or weights while providing one or more of the structural characteristics discussed herein. Applicants believe that the design of the wall thickness and / or weight allows the hard hat to provide a high level of impact protection while allowing for greater user comfort, which is particularly important in the context of a protective work helmet / hard hat, where the user may wear the device for several hours during a workday / shift. In addition, applicants believe that the hard hat designs discussed herein increase ventilation (lowering the air temperature near the user's head), keep the center of mass close to the center of the wearer's head, reduce the weight of the hard hat, and thereby reduce neck and / or back fatigue, reduce pressure points on the wearer's head, and allow additional accessories to be worn simultaneously.

[0055] In particular embodiments, the total weight of the hard hat 10 includes the outer shell, the linear impact absorbing layer 42, and the rotational impact absorbing layer 44. In particular embodiments, the total weight of the hard hat 10 is less than the maximum total weight of the hard hat 10.

[0056] In a specific embodiment, the linear impact absorbing layer 42 has a thickness T2. In a specific embodiment, the linear impact absorbing layer 42 has a thickness T2. In various embodiments, T2 is less than the maximum thickness of the linear impact absorbing layer 42.

[0057] In a particular embodiment, the rotational impact absorbing layer 44 has a thickness T3. In various embodiments, T3 is less than T2. ​​In various embodiments, the linear impact absorbing layer 42 has a first thickness and the rotational impact absorbing liner 44 has a second thickness. In such embodiments, the first thickness is different from the second thickness. In such embodiments, the second thickness is less than the first thickness.

[0058] In a specific embodiment, the rotational impact absorbing layer 44 has a thickness T3 of less than 10 mm, less than 8 mm, and specifically has a thickness between 2 mm and 8 mm, and more specifically between 4 mm and 6 mm. In a specific embodiment, T3 is about 6 mm (i.e., 6 mm ± 0.4 mm). In a specific embodiment, T3 is about 4 mm (i.e., 4 mm ± 0.1 mm). In various embodiments, the average thickness of the rotational impact absorbing layer 44 is less than 8 mm.

[0059] In various embodiments, the thickness of the rotational impact absorbing layer 44 positioned at the crown portion 22 is less than the thickness of the rotational impact absorbing layer 44 positioned near the bottom section 24. In a specific embodiment, the thickness of the rotational impact absorbing layer 44 positioned at the crown portion 22 is about 4 mm (i.e., 4 mm ± 0.1 mm), and the thickness of the rotational impact absorbing layer 44 positioned near the bottom section 24 is about 6 mm (i.e., 6 mm ± 0.2 mm).

[0060] In a specific embodiment, the thickness of the rotational impact absorbing layer 44 located at the crown portion 22 is different from the thickness of the rotational impact absorbing layer 44 located at the side or near the bottom section 24, the thickness of the rotational impact absorbing layer 44 located near the front 28, and the thickness of the rotational impact absorbing layer 44 located near the rear portion 68 of the hard hat 10. In this embodiment, the thickness of the rotational impact absorbing layer 44 located at the crown portion 22 is about 4 mm (i.e., 4 mm ± 0.1 mm), the thickness of the rotational impact absorbing layer 44 located at the side or near the bottom section 24 is about 5.66 mm (i.e., 5.66 mm ± 0.1 mm), the thickness of the rotational impact absorbing layer 44 located near the front 28 is about 5.66 mm (i.e., 5.66 mm ± 0.1 mm), and the thickness of the rotational impact absorbing layer 44 located near the rear portion 68 of the hard hat 10 is about 5.8 mm (i.e., 5.8 mm ± 0.1 mm).

[0061] In a specific embodiment, the total thickness of the hard hat 10 at the crown portion 22 (including all of the outer shell 12 and the impact absorbing insert 40, i.e., T1+T2+T3) is T4. In a specific embodiment, the total thickness T4 of the hard hat 10 at the crown portion 22 (including all of the outer shell 12 and the impact absorbing insert 40, i.e., T1+T2+T3) is less than the maximum total thickness of the hard hat 10.

[0062] As previously mentioned, the applicant believes that the helmet design discussed herein provides improved impact protection due to the reduced peak rotational acceleration and / or reduced combined linear acceleration and peak rotational acceleration, which reduces the risk and / or possibility of injury to the helmet wearer. The applicant determined the difference in peak rotational acceleration and linear acceleration by testing the helmet design discussed herein, alternative helmet designs marked as 1-piece prototypes and 3-piece prototypes currently unavailable commercially by Milwaukee Electric Tool Corporation, and other available helmets. The test was performed using the Rheon test method described in "The Traumatic Brain Injury Mitigation Effects of a New Viscoelastic Add-on Liner" (Siegkas, P., Sharp, DJ and Ghajari, M. The traumatic brain injury mitigation effects of a new viscoelastic add-on liner, Sci Rep 9, 3471 (2019)) as published in Scientific Reports, which is incorporated herein by reference as a whole. All samples were tested using an impact velocity of 6.5 m / s, an impact anvil angle of 45 degrees, and the three impact locations described herein (front side 70, side 72, rear side 74). In addition, various impact performance tests were conducted using the Virginia Tech impact test method as described in "STAR Methodology for Bicycle Helmets", published by Virginia Tech (Megan L. Bland, Craig McNally, Steven Rowson, Star Methodology for Bicycle Helmets, VIRGINIATECH https: / / vtechworks.lib.vt.edu / bitstream / handle / 10919 / 83760 / Bicycle%20STAR%20Methodology.pdf?sequence=1&isAllowed=y), which is incorporated herein by reference in its entirety. All samples tested under the Virginia Tech method were tested using an impact velocity of 6.5 m / s, an impact anvil angle of 45 degrees, and the three impact locations described herein (front side 70, side 72, rear side 74).

[0063] Test Example

[0064] Reference Fig. 9, shows a graph showing the peak linear acceleration of the hard hat designs discussed herein compared to various conventional hard hat designs after testing using the Rheon test method. In a specific embodiment, under the Rheon test method, the peak linear acceleration of the hard hat designs discussed herein is less than the peak linear acceleration of various conventional hard hats when tested at the right front position 70, the left side position 72, and / or the right rear position 74. In such an embodiment, the peak linear acceleration is less than the maximum peak linear acceleration.

[0065] In a specific embodiment, under the Rheon test method, the peak linear acceleration at the right front position 70 is less than 70 meters per second 2 , at the left position 72 the peak linear acceleration is less than 70 m / s 2 and the peak linear acceleration at the right rear position 74 is less than 50 m / s 2 In a specific embodiment, when the rotational impact absorbing liner 44 is formed of three pieces, the peak linear acceleration at the right front position 70 is less than 70 meters per second under the Rheon test method. 2 , at the left position 72 the peak linear acceleration is less than 70 m / s 2 and the peak linear acceleration at the right rear position 74 is less than 40 m / s 2 .

[0066] In a specific embodiment, when the rotational impact absorbing liner 44 is formed from one piece, the peak linear acceleration at the right front position 70 under the Rheon test method is less than 65 meters per second 2 , the peak linear acceleration at the left position 72 is less than 50 m / s 2 , the peak linear acceleration at the right rear position 74 is less than 50 m / s 2 In a specific embodiment, when the rotational impact absorbing liner 44 is formed from one piece, the peak linear acceleration at the right front position 70 under the Rheon test method is less than 60 meters per second. 2 , the peak linear acceleration at the left position 72 is less than 45 m / s 2 and the peak linear acceleration at the right rear position 74 is less than 45 m / s 2 .

[0067] Reference Fig.10, shows a graph showing the peak linear acceleration of the hard hat designs discussed herein compared to various conventional hard hat designs after testing using the Virginia Tech test method. In a specific embodiment, under the Virginia Tech test method, the peak linear acceleration of the hard hat designs discussed herein is less than the peak linear acceleration of various conventional hard hats when tested at the right front position 70 and / or the right rear position 74. In such an embodiment, the peak linear acceleration is less than the maximum peak linear acceleration.

[0068] In a specific embodiment, the peak linear acceleration at the right front position 70 is less than 130 m / s under the Virginia Tech test method. 2 , the peak linear acceleration at the left position 72 is less than 145 m / s 2 , and the peak linear acceleration at the right rear position 74 is less than 90 m / s 2 In a specific embodiment, when the rotational impact absorbing liner 44 is formed from three pieces, the peak linear acceleration at the right front position 70 is less than 130 meters per second under the Virginia Tech test method. 2 , the peak linear acceleration at the left position 72 is less than 145 m / s 2 , and the peak linear acceleration at the right rear position 74 is less than 90 m / s 2 .

[0069] Reference Fig.11 , shows a graph showing the peak rotational acceleration of the hard hat designs discussed herein compared to various conventional hard hat designs after testing using the Virginia Tech test method. In a specific embodiment, under the Virginia Tech test method, the peak rotational acceleration of the hard hat designs discussed herein is less than the peak rotational acceleration of some of the various conventional hard hats when tested at the right front position 70, the left side position 72, and / or the right rear position 74. In such an embodiment, the peak rotational acceleration is less than the maximum peak rotational acceleration.

[0070] In a specific embodiment, the peak rotational acceleration at the right front position 70 is less than 5500 rad / s under the Virginia Tech test method. 2 , and more specifically less than 5200 rad / s 2 In a specific embodiment, the peak rotational acceleration at the left position 72 is less than 4500 rad / s under the Virginia Tech test method. 2 , and more specifically less than 4200 rad / s 2 In a specific embodiment, the peak rotational acceleration at the right rear location 74 is less than 5500 rad / s under the Virginia Tech test method.2 .

[0071] In a specific embodiment, the peak rotational acceleration is less than 5500 rad / s under the Virginia Tech test method. 2 In such an embodiment, the peak rotational acceleration is greater than 4000 rad / s under the Virginia Tech test method. 2 In other words, under the Virginia Tech test method, the peak rotational acceleration is 4000 rad / s. 2 with 5500 rad / s 2 In various embodiments, under the Virginia Tech test method, the peak rotational acceleration at the right front position 70, the left side position 72, and the right rear side position 74 is 4000 rad / s. 2 with 5500 rad / s 2 between.

[0072] Reference Fig.12 , shows a graph showing the peak rotational acceleration of the hard hat designs discussed herein compared to various conventional hard hat designs after testing using the Rheon test method. In a specific embodiment, under the Rheon test method, the peak rotational acceleration of the hard hat designs discussed herein is less than the peak rotational acceleration of various conventional hard hats when tested at the right front position 70, the left side position 72, and / or the right rear position 74. In such an embodiment, the peak rotational acceleration is less than the maximum peak linear acceleration.

[0073] In a specific embodiment, the peak rotational acceleration at the right front position 70 is less than 7000 rad / s 2 In a specific embodiment, the peak rotational acceleration at the left position 72 is less than 9000 rad / s 2 In a specific embodiment, the peak rotational acceleration at the right rear position 74 is less than 7000 rad / s 2 In another embodiment, the peak rotational acceleration at the right front position 70 is less than 7000 rad / s 2 , the peak rotational acceleration at the left position 72 is less than 8500 rad / s 2 , and the peak rotational acceleration at the right rear position 74 is less than 6500 rad / s 2 .

[0074] In a particular embodiment, when the rotational impact absorbing liner 44 is formed from three pieces, the peak rotational acceleration at the right front position 70 is less than 7000 rad / sec. 2 In a specific embodiment, the peak rotational acceleration at the left position 72 is less than 9000 rad / s 2In another embodiment, the peak rotational acceleration at the left position 72 is less than 8500 rad / s 2 In a specific embodiment, the peak rotational acceleration at the right rear position 74 is less than 6000 rad / s 2 In another embodiment, the peak rotational acceleration at the right rear position 74 is less than 5500 rad / s 2 In various embodiments, the peak rotational acceleration at the right front position 70 is less than 7000 rad / s 2 , the peak rotational acceleration at the left position 72 is less than 8500 rad / s 2 , and the peak rotational acceleration at the right rear position 74 is less than 5500 rad / s 2 .

[0075] In a particular embodiment, when the rotational impact absorbing liner 44 is formed from one piece, the peak rotational acceleration at the right front position 70 is less than 6000 rad / sec. 2 In a specific embodiment, the peak rotational acceleration at the left position 72 is less than 6000 rad / s 2 In a specific embodiment, the peak rotational acceleration at the right rear position 74 is less than 6500 rad / s 2 In a specific embodiment, the peak rotational acceleration is less than 7000 radians per second under the Rheon test method. 2 In such an embodiment, the peak rotational acceleration under the Rheon test method is greater than 5000 rad / s 2 In other words, under the Rheon test method, the peak rotational acceleration is 5000 rad / s. 2 with 7000 rad / s 2 In various embodiments, under the Rheon test method, the peak rotational acceleration at the right front position 70, the left side position 72, and the right rear side position 74 is 5000 rad / s. 2 with 7000 rad / s 2 between.

[0076] Applicants believe that, unlike conventional helmets that rely on a large amount of translation and / or sliding motion (i.e., 10 mm to 15 mm), the helmets discussed herein do not require a large sliding plane and / or displacement to absorb impact energy. As previously described, applicants believe that impact systems that rely on a large sliding plane for translation and / or motion have a time delay between when the impact and translation begin, and therefore a delay between when the impact and energy is absorbed. Applicants believe that the helmet and rotational impact layer can reduce the rotational acceleration experienced by the helmet wearer and reduce translation and / or sliding motion. Applicants believe that the amount of translation and / or sliding motion S of the inner surface 54 of the rotational absorption layer 44 relative to the linear impact absorption layer 42 is reduced. In various embodiments, the translation and / or sliding motion S of the rotational absorption layer 44 is less than the maximum translation distance.

[0077] Applicants believe that the helmet designs discussed herein reduce the amount of impact and / or energy experienced by the wearer and therefore reduce the likelihood of injury, such as Figure 13 to Figure 14 shown.

[0078] Reference Fig.13 , shows a graph showing the probability of injury or concussion risk for helmet design 10 compared to a bare head and four conventional helmet designs based on the above Rheon test method. Applicants use the following formula to calculate concussion risk:

[0079]

[0080] In the concussion risk formula, α is equal to the rotational acceleration (rad / s 2 ), and a is equal to the linear acceleration (g).

[0081] In various embodiments, under the Rheon test method, when tested at the right front position 70, the left side position 72 and / or the right rear side position 74, the hard hat design discussed herein has a reduced probability of injury compared to the probability of injury of a conventional hard hat. In such an embodiment, the probability of injury is less than the maximum probability of injury. In a specific embodiment, when tested at the right front position 70, the probability of injury is reduced by 70% to 90%, particularly 80% to 90%, and more particularly by about 84% compared to a conventional hard hat design. In a specific embodiment, when tested at the left side position 72, the probability of injury is reduced by 50% to 70%, particularly 55% to 65%, and more particularly by about 59% compared to a conventional hard hat design. In a specific embodiment, when tested at the right rear side position 74, the probability of injury is reduced by 15% to 35%, particularly 20% to 30%, and more particularly by about 24% compared to a conventional hard hat design.

[0082] Reference Fig.14 , shows a graph showing the injury probability or concussion risk of a hard hat design 10 compared to a bare head and four conventional hard hat designs based on the Virginia Tech test method described above. In various embodiments, under the Virginia Tech test method, when tested at the right front position 70, the left side position 72, and / or the right rear position 74, the hard hat designs discussed herein have a reduced injury probability compared to the injury probabilities of various conventional hard hats.

[0083] In such an embodiment, the probability of injury is less than the maximum probability of injury. In a specific embodiment, when tested at the right front position 70, the probability of injury is reduced by 5% to 20%, particularly 8% to 15%, and more particularly by about 11% compared to conventional helmet designs.

[0084] It should be understood that the drawings illustrate exemplary embodiments in detail, and it should be understood that the present application is not limited to the details or methods set forth in the description or illustrated in the drawings. It should also be understood that the terminology is used for descriptive purposes only and should not be considered as limiting.

[0085] In view of this description, other modifications and alternative embodiments of various aspects of the present invention will be obvious to those skilled in the art. Therefore, this description should be interpreted as being illustrative only. The construction and arrangement shown in various exemplary embodiments are illustrative only. Although only several embodiments are described in detail in the present disclosure, many modifications (for example, variations in the size, size, structure, shape and proportion of various elements, the value of parameters, the installation arrangement, the use of materials, colors, orientations, etc.) are possible without substantially departing from the novel teachings and advantages of the subject matter described herein. Some elements shown as being integrally formed can be constructed by multiple parts or elements, the position of the elements can be reversed or otherwise changed, and the nature or number of discrete elements or positions can be changed or changed. The order or sequence of any process, logical algorithm or method steps can be changed or reordered according to alternative embodiments. Without departing from the scope of the present disclosure, other replacements, modifications, changes and omissions can also be made in the design, operating conditions and arrangements of various exemplary embodiments.

[0086] Unless expressly stated otherwise, it is not intended that any method described herein be interpreted as requiring that its steps be performed in a particular order. Therefore, in the event that a method claim does not actually recite the order in which its steps are followed or does not otherwise specify in the claim or description that the steps are to be limited to a particular order, it is not intended to infer any particular order. In addition, as used herein, the expression "a" is intended to include one or more parts or elements, and is not intended to be interpreted as meaning only one. As used herein, "rigidly coupled" refers to two parts being coupled in such a way that the parts move together in a fixed positional relationship when subjected to force.

[0087] Various embodiments of the present disclosure are directed to any combination of any of the features, and any such combination of features may be claimed in this or a future application. Any of the features, elements, or components of any of the exemplary embodiments discussed above may be used alone or in combination with any of the features, elements, or components of any of the other embodiments discussed above.

[0088] For purposes of this disclosure, the term "coupled" refers to the joining of two components to one another, either directly or indirectly. Such joining may be stationary in nature or movable in nature. Such joining may be achieved by the two members and any additional intermediate members being integrally formed as a single unitary body with one another, or by the two members being attached to one another or the two members and any additional members being attached to one another. Such joining may be permanent in nature, or alternatively may be removable or releasable in nature.

[0089] Although the current application describes a specific combination of features in the claims attached hereto, the various embodiments created by the present invention relate to any combination of any of the features described herein, whether or not such combination is currently claimed, and any such combination of features may be claimed in this application or in a future application. Any of the features, elements, or components of any of the exemplary embodiments discussed above may be used alone or in combination with any of the features, elements, or components of any of the other embodiments discussed above.

[0090] In various exemplary embodiments, relative dimensions including angles, lengths, and radii as shown in the drawings are drawn to scale. Actual measurements of the drawings will disclose the relative dimensions, angles, and ratios of the various exemplary embodiments. The various exemplary embodiments extend to various ranges around absolute and relative dimensions, angles, and ratios that can be determined from the drawings. The various exemplary embodiments include any combination of one or more relative dimensions or angles that can be determined from the drawings. In addition, actual dimensions not explicitly set forth in this description can be determined by using ratios of dimensions measured in the drawings in conjunction with explicit dimensions set forth in this description.

Claims

1. A protective work helmet comprising: A housing, the housing comprising: External surface; an inner surface defining a cavity sized to receive a user's head; a crown portion configured to cover a portion of a user's head, wherein a bottom section of the crown portion defines a lower circumference extending along the outer surface of the housing; a brim extending radially outward from a portion of the lower circumference; and a front mounting ridge configured to couple an accessory to the protective work helmet; a linear impact absorbing material located within the housing; and A rotational shock absorbing material is disposed within the housing, the rotational shock absorbing material comprising a strain rate sensitive material, wherein the stiffness of the rotational shock absorbing material increases when subjected to an impact.

2. The protective work helmet according to claim 1, wherein: The rotational shock absorbing material is a unitary piece of polymer material comprising a plurality of cells coupled to an inner surface of the linear shock absorbing material.

3. The protective work helmet according to claim 1, wherein: The linear impact absorbing material is a polymer foam material having an outer surface coupled to the inner surface of the outer shell.

4. The protective work helmet according to claim 1, wherein: The total weight of the protective work helmet is less than 20 ounces.

5. The protective work helmet according to claim 4, wherein: The total weight of the protective work helmet is between 13 ounces and 20 ounces.

6. The protective work helmet of claim 1 further comprising a mounting ridge coupled to a lateral side of the bottom section of the crown portion, the mounting ridge comprising: a first end portion; a second end portion; as well as A plurality of slots are positioned along the mounting ridge between the first end and the second end.

7. A protective work helmet comprising: A housing, the housing being formed of a rigid material, the housing comprising: External surface; an inner surface defining a cavity sized to receive a user's head; a crown portion configured to cover a portion of a user's head, wherein a bottom section of the crown portion defines a lower circumference extending along the outer surface of the housing; a brim extending radially outward from a portion of the lower circumference; and a polymer foam insert located within the shell and having a certain thickness, the polymer foam insert comprising: an outer surface facing the inner surface of the housing; and an interior surface facing inward; and A rotational shock absorbing liner is coupled to the inner surface of the polymer foam insert, the rotational shock absorbing liner comprising a strain rate sensitive material, wherein a stiffness of the rotational shock absorbing liner increases upon impact.

8. The protective work helmet according to claim 7, wherein: The thickness of the rotational impact absorbing lining is less than 8 mm.

9. The protective work helmet according to claim 8, wherein: The rotational impact absorbing liner has a thickness between 2 mm and 8 mm.

10. The protective work helmet according to claim 7, wherein: The polymer foam insert has a first thickness and the rotational impact absorbing liner has a second thickness, and wherein the first thickness is different than the second thickness.

11. The protective work helmet according to claim 10, wherein: The second thickness is smaller than the first thickness.

12. A protective work helmet comprising: A housing, the housing comprising: External surface; an inner surface defining a cavity sized to receive a user's head; a crown portion configured to cover a portion of a user's head, wherein a bottom section of the crown portion defines a lower circumference extending along the outer surface of the housing; a brim extending radially outward from a portion of the lower circumference; and a front mounting ridge configured to couple an accessory to the protective work helmet; and A shock absorbing insert, the shock absorbing insert comprising: a linear impact absorbing material located within the housing; and a rotational shock absorbing material, the rotational shock absorbing material being located within the housing; wherein the impact absorbing insert is configured to provide less than 7000 rad / sec under the Rheon test method 2 The peak rotational acceleration.

13. The protective work helmet according to claim 12, wherein: Under the Rheon test method, the peak rotational acceleration is greater than 5000 rad / s 2 .

14. The protective work helmet of claim 12, wherein: The rotational shock absorbing material is a unitary piece of polymer material comprising a plurality of cells coupled to an inner surface of the linear shock absorbing material.

15. The protective work helmet of claim 12, wherein: The average thickness of the rotational impact absorbing material is less than 8 mm.

16. The protective work helmet of claim 12, wherein: The thickness of the portion of the rotational shock absorbing material at the crown portion is less than the thickness of the rotational shock absorbing material near the sole section.

17. The protective work helmet of claim 16, wherein: The thickness of the portion of the rotational impact absorbing material at the crown portion is approximately 4 mm.

18. The protective work helmet of claim 16, wherein: The thickness of a portion of the rotational impact absorbing material located near the bottom section is about 6 mm.

19. The protective work helmet of claim 12, further comprising an auxiliary mounting ridge coupled to a lateral side of the bottom section of the crown portion, the auxiliary mounting ridge comprising: a first end portion; a second end portion; as well as A plurality of slots are positioned along the auxiliary mounting ridge between the first end and the second end.

20. The protective work helmet of claim 12, wherein: The linear shock absorbing material has a first thickness and the rotational shock absorbing material has a second thickness, and wherein the second thickness is less than the first thickness.

21. A protective work helmet comprising: A housing, the housing comprising: External surface; an inner surface defining a cavity sized to receive a user's head; a crown portion configured to cover a portion of a user's head, wherein a bottom section of the crown portion defines a lower circumference extending along the outer surface of the housing; a brim extending radially outward from a portion of the lower circumference; and a front mounting ridge configured to couple an accessory to the protective work helmet; and A shock absorbing insert, the shock absorbing insert comprising: a linear impact absorbing material located within the housing; and a rotational shock absorbing material, the rotational shock absorbing material being located within the housing; wherein the impact absorbing insert is configured to provide less than 5500 rad / sec under the Virginia Tech test method 2 A peak rotational acceleration of greater than 4000 rad / s under the Virginia Tech test method 2 .

22. A protective work helmet comprising: A housing, the housing comprising: External surface; an inner surface defining a cavity sized to receive a user's head; a crown portion configured to cover a portion of a user's head, wherein a bottom section of the crown portion defines a lower circumference extending along the outer surface of the housing; a brim extending radially outward from a portion of the lower circumference; and a front mounting ridge configured to couple an accessory to the protective work helmet; and A shock absorbing insert, the shock absorbing insert comprising: a linear impact absorbing material, the linear impact absorbing material being located within the housing; a rotational shock absorbing material, the rotational shock absorbing material being located within the housing; wherein the impact absorbing insert is configured to provide less than 7000 rad / sec under the Rheon test method 2 The peak rotational acceleration of the impact absorbing insert is configured to provide a peak rotational acceleration of less than 70 m / s under the Rheon test method. 2 The peak linear acceleration.

23. A protective work helmet comprising: A housing, the housing comprising: External surface; an inner surface defining a cavity sized to receive a user's head; a crown portion configured to cover a portion of a user's head, wherein a bottom section of the crown portion defines a lower circumference extending along the outer surface of the housing; a brim extending radially outward from a portion of the lower circumference; and a front mounting ridge configured to couple an accessory to the protective work helmet; and A shock absorbing insert, the shock absorbing insert comprising: a linear impact absorbing material, the linear impact absorbing material being located within the housing; a rotational shock absorbing material, the rotational shock absorbing material being located within the housing; Wherein, the impact absorbing insert is configured to provide 4000 rad / sec under the Virginia Tech test method 2 with 5500 rad / s 2 and wherein the impact absorbing insert is configured to provide a rotational acceleration of less than 145 m / s under the Virginia Tech test method. 2 The peak linear acceleration.

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