Abstract:
A garment worn by a wearer has an exterior shell and an interior shell with impact absorbing material comprising various structures between the exterior shell and the interior shell. When force is applied to the exterior shell, the structures of the impact absorbing materials deform (e.g., compress), reducing the force received by the interior shell. For example, the impact absorbing material forms structures such as multiple branched “Y” shapes or multiple cylindrical rods with a surface contacting the exterior shell and a surface contacting the interior shell. The interior of the rods and other impact absorbing structures may be filled with a deformable material, such as foam. The impact absorbing material may be formed into jacks, spherical shapes, bristles, intersecting arches, or other shapes positioned between the exterior shell and the interior shell.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/276,793, filed Jan. 8, 2016, which is incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    A helmet protects a skull of the wearer from collisions with the ground, equipment, and other players. Present helmets were designed with the primary goal of preventing traumatic skull fractures and other blunt trauma. In general, a helmet includes a hard, rounded shell and cushioning inside the shell. When another object collides with the helmet, the rounded shape deflects at least some of the force tangentially while the hard shell distributes the normal force over a wider area of the head. Such helmets have been successful at preventing skull fractures but leave the wearer vulnerable to concussions. 
         [0003]    A concussion occurs when the skull changes velocity rapidly relative to the enclosed brain and cerebrospinal fluid. The resulting collision between the brain and the skull results in a brain injury with neurological symptoms such as memory loss. Although the cerebrospinal fluid cushions the brain from small forces, the fluid does not absorb all the energy from collisions that arise in sports such as football, hockey, skiing, and biking. Helmets include cushioning to dissipate some of the energy absorbed by the hard shell, but the cushioning is insufficient to prevent concussions from violent collisions or from the cumulative effects of many lower velocity collisions. 
       SUMMARY 
       [0004]    In various embodiments, a helmet includes two generally concentric shells with impact absorbing structures between the shells. The inner shell may be somewhat rigid to protect against skull fracture and the outer shell may also somewhat rigid to spread impact forces over a wider area of the impact absorbing structures positioned inside the outer shell, or the outer shell may be more flexible such that impact forces locally deform the outer shell to transmit forces to a smaller, more localized section of the impact absorbing structures positioned inside the outer shell. The impact absorbing structures are secured between the generally concentric shells and have sufficient strength to resist forces from mild collisions. However, the impact absorbing structures undergo deformation (e.g., buckling) when subjected to forces from a sufficiently strong impact force. As a result of the deformation, the impact absorbing structures reduce energy transmitted from the outer shell to the inner shell, thereby reducing forces on the wearer&#39;s skull and brain. The impact absorbing structures may also allow the outer shell to move independently of the inner shell in a variety of planes or directions. Thus, impact absorbing structures reduce the incidence and severity of concussions as a result of sports and other activities. When the outer and inner shell move independently from one another, rotational acceleration, which contributes to concussions, may also be reduced. 
         [0005]    The impact absorbing structures may include impact absorbing members mechanically secured between the outer shell and the inner shell. In one example embodiment, an impact absorbing member comprises a column having one end secured to the inner shell and an opposite end secured to the outer shell. In another example, the impact absorbing member includes three portions joined at one point to form a branched shape. One of the portions is secured to the inner shell, and the other two portions are secured to the outer shell, or vice versa. By varying the length, width, and attachment angles of the impact absorbing members, the helmet manufacturer can control the threshold amount of force that results in deformation. 
         [0006]    Alternatively, the impact absorbing structure may be secured to only one of the shells. When deformation occurs, the impact absorbing structure contacts an opposite shell or an impact absorbing structure secured to the opposite shell. Once the impact absorbing structure makes contact, the overall stiffness of the helmet increases, and the impact absorbing structure deforms to absorb energy. For example, ends of intersecting arches, bristles, or jacks are attached to the inner shell, the outer shell, or both. 
         [0007]    The impact absorbing structures may also be packed between the inner and outer shells without necessarily being secured to either the inner shell or outer shell. The space between the impact absorbing structures may be filled with air or a cushioning material (e.g., foam) that further absorbs energy and prevents the impact absorbing structures from rattling if they are not secured to either shell. The packed arrangement of the impact absorbing structures simplifies manufacturing without reducing the overall effectiveness of the helmet. 
         [0008]    The helmet may include modular rows to facilitate manufacturing. A modular row includes an inner surface, an outer surface, and impact absorbing structures between the inner and outer surfaces. A modular row is relatively thin and flat compared to the assembled helmet, which reduces the complexity of forming the impact absorbing structures between the modular row&#39;s inner and outer surfaces. For example, the modular rows may be formed by injection molding, fusible core injection molding, or a lost wax process, techniques which may not be feasible for molding the entire impact absorbing structures in its final form. When assembled, the inner surfaces of the modular rows may form part of the inner shell, and the outer surfaces of the modular rows may form part of the outer shell. Alternatively or additionally, the modular rows may be assembled between an innermost shell and an outermost shell that laterally secure the modular rows and radially contain them. Alternatively or additionally, adjacent rows may be laterally secured to each other. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of an assembly of impact absorbing structures formed from modular rows, in accordance with an embodiment. 
           [0010]      FIG. 2  is a perspective view of a modular row, in accordance with an embodiment. 
           [0011]      FIG. 3  is a perspective view of a modular row, in accordance with an embodiment. 
           [0012]      FIG. 4  is a plan view of an impact absorbing member having a branched shape, in accordance with an embodiment. 
           [0013]      FIG. 5A  is a perspective view of impact absorbing structures including intersecting arches, in accordance with an embodiment. 
           [0014]      FIG. 5B  is a perspective view of an opposing arrangement of the impact absorbing structures of  FIG. 5A , in accordance with an embodiment. 
           [0015]      FIG. 5C  is a perspective view of impact absorbing structures including intersecting arches connected by a column, in accordance with an embodiment. 
           [0016]      FIG. 6A  is a cross-sectional view of a helmet including impact absorbing structures having a spherical wireframe shape, in accordance with an embodiment. 
           [0017]      FIG. 6B  is a plan view of an impact absorbing structure included in the helmet of  FIG. 6A , in accordance with an embodiment. 
           [0018]      FIG. 6C  is a perspective view of an impact absorbing structure included in the helmet of  FIG. 6A , in accordance with an embodiment. 
           [0019]      FIG. 7A  is a cross-sectional view of a helmet including impact absorbing structures having a jack shape, in accordance with an embodiment. 
           [0020]      FIG. 7B  is a plan view of an impact absorbing structure included in the helmet of  FIG. 7A , in accordance with an embodiment. 
           [0021]      FIG. 7C  is a perspective view of an impact absorbing structure included in the helmet of  FIG. 7A , in accordance with an embodiment. 
           [0022]      FIG. 8A  is a cross-sectional view of a helmet including impact absorbing structures having a bristle shape, in accordance with an embodiment. 
           [0023]      FIG. 8B  is a cross-sectional view of an impact absorbing structure included in the helmet of  FIG. 8A , in accordance with an embodiment. 
           [0024]      FIG. 8C  is a perspective view of an impact absorbing structure included in the helmet of  FIG. 8A , in accordance with an embodiment. 
           [0025]      FIG. 9  is a perspective view of an embodiment of an impact absorbing structure having a conical structure, in accordance with an embodiment. 
           [0026]      FIG. 10  is a perspective view of an embodiment of an impact absorbing structure having a base portion and angled support portions, in accordance with an embodiment. 
           [0027]      FIG. 11  is a perspective view of an embodiment of an impact absorbing structure having a cylindrical member coupled to multiple planar surfaces, in accordance with an embodiment. 
           [0028]      FIG. 12  is a perspective view of an embodiment of an impact absorbing structure having a base portion to which multiple supplemental portions are coupled, in accordance with an embodiment. 
           [0029]      FIG. 13A  is a perspective view of an embodiment of a conical impact absorbing structure, in accordance with an embodiment. 
           [0030]      FIG. 13B  is a cross-sectional view of an alternative impact absorbing structure, in accordance with an embodiment. 
           [0031]      FIG. 14  is a side view of an impact absorbing structure having arched structures, in accordance with an embodiment. 
           [0032]      FIG. 15  is a perspective and cross-sectional view of an embodiment of an impact absorbing structure comprising a cylindrical structure enclosing a conical structure, in accordance with an embodiment. 
           [0033]      FIG. 16  is a perspective view of an impact absorbing structure, in accordance with an embodiment. 
           [0034]      FIGS. 17A-17C  show perspective views of impact absorbing structures comprising connected support members, in accordance with an embodiment. 
           [0035]      FIGS. 18-20  show example structural groups including multiple support members positioned relative to each other with different support members coupled to each other by connecting members, in accordance with an embodiment. 
       
    
    
     DETAILED DESCRIPTION 
     Modular Helmet 
       [0036]      FIG. 1  is a perspective view of an assembly  100  of impact absorbing structures formed from modular rows  110 ,  120 , and  130 , in accordance with an embodiment. In general, a modular row includes an inner surface, an outer surface, and impact absorbing structures between the inner surface and the outer surface. The modular row may further include a protective layer (e.g., foam) less rigid than the impact absorbing structures that encloses a remaining volume between the inner surface and outer surface after formation of the impact absorbing structures. When a helmet including the assembly  100  is worn, the inner surface is closer to the user&#39;s skull than the outer surface. Optionally, the modular row includes end surfaces connecting the short edges of the inner surface to the short edges of the outer surface. The inner surface, outer surface, and end surfaces form a slice with two parallel flat sides and an arc or bow shape on two other opposing sides. The end surfaces may be parallel to each other or angled relative to each other. The modular rows include one or more base modular rows  110 , crown modular rows  120 , and rear modular rows  130 . The assembly  100  may include further shells, such as an innermost shell, an outermost shell, or both, that secure the modular rows relative to each other and capture the structure between the innermost and outermost shells when assembled for durability and impact resistance. 
         [0037]    The base modular row  110  encircles the wearer&#39;s skull at approximately the same vertical level as the user&#39;s brow. The crown modular rows  120  are stacked horizontally on top of the base modular row  110  so that the long edges of the inner and outer surfaces form parallel vertical planes. The end surfaces of the crown modular rows  120  rest on a top plane of the base modular row. The outer surfaces of the crown modular rows  120  converge with the outer surface of the base modular row  110  to form a rounded outer shell. Likewise, the inner surfaces of the crown modular rows  120  converge with the inner surface of the base modular row  110  to form a rounded inner shell. Thus, the crown modular rows  120  and base modular row  110  form concentric inner and outer shells protecting the wearer&#39;s upper head. The outer surface of a crown modular row  120  may form a ridge  122  raised relative to the rest of the outer surface. The ridge  122  may improve distribution of impact forces or facilitate a connection between two halves (e.g., left and right halves) of an outermost layer of a helmet including assembly  100 . 
         [0038]    The rear modular rows  130  are stacked vertically under a rear portion of the base modular row  110  so that the long edges of the inner and outer surfaces form parallel horizontal planes. The inner surface of the topmost rear modular row  130  forms a seam with the inner surface of the base modular row  110 , and the outer surface of the topmost rear modular row  130  forms a seam with the outer surface of the base modular row  110 . Thus, the rear modular rows  130  and the rear portion of the base modular row  110  form concentric inner and outer shells protecting the wearer&#39;s rear lower head and upper neck. 
       Modular Row 
       [0039]      FIG. 2  is a perspective view of a base modular row  110 , in accordance with an embodiment. The base modular row  110  includes two concentric surfaces  103  (e.g., an inner surface and an outer surface), end surfaces, and impact absorbing structures  105 . 
         [0040]    As illustrated, the impact absorbing structures  105  are columnar impact absorbing member is mechanically secured to both concentric surfaces  103 . An end of the impact absorbing structure  105  may be mechanically secured to a concentric surface  103  as a result of integral formation, by a fastener, by an adhesive, by an interlocking end portion (e.g., a press fit), another technique, or a combination thereof. An end of the impact absorbing member is secured perpendicularly to the local plane of the concentric surface  103  in order to maximize resistance to normal force. However, one or more of the impact absorbing members may be secured at another angle to modify the resistance to normal force or to improve resistance to torque due to friction between an object and the outermost surface of a helmet including assembly  100 . The critical force that buckles the impact absorbing member increases with the diameter of the impact absorbing member and decreases with the length of the impact absorbing member. 
         [0041]    Generally, an impact absorbing member has a circular cross section to eliminate stress concentration along edges, but other cross-sectional shapes (e.g., squares, hexagons) may be used to simplify manufacturing or modify performance characteristics. Generally, an impact absorbing structure is formed from a compliant, yet strong material such as an elastomeric substrate such as hard durometer plastic (e.g., polyurethane, silicone) and may include a core of a softer material such as open or closed-cell foam (e.g., polyurethane, polystyrene) or fluid (e.g., air). After forming the impact absorbing members, a remaining volume between the concentric surfaces  103  (that is not filled by the impact absorbing members) may be filled with a softer material such as foam or a fluid (e.g., air). 
         [0042]    The concentric surfaces  103  are curved to form an overall rounded shape (e.g., spherical, ellipsoidal) when assembled into a helmet shape. The concentric surfaces  103  and end surfaces  104  may be formed from a material that has properties stiffer than the impact absorbing members such as hard plastic, foam, metal, or a combination thereof, or formed from the same material as the impact absorbing members. To facilitate manufacturing of the base modular row  110 , a living hinge technique may be used. The base modular row  110  may be manufactured as an initially flat modular row, where the long edges of the concentric surfaces  103  form two parallel planes. For example, the base modular row  110  is formed by injection molding the concentric surfaces  103 , the end surfaces  104 , and the impact absorbing structures  105 . The base modular row  110  may then be bent to form a living hinge. The living hinge may be created by injection molding a thin section of plastic between adjacent structures. The plastic is injected into the mold such that the plastic fills the mold by crossing the hinge in a direction transverse to the axis of the hinge, thereby forming polymer strands perpendicular to the hinge, thereby creating a hinge that is robust to cracking or degradation. 
         [0043]      FIG. 3  is a perspective view of a modular row  110 , in accordance with an embodiment. The modular row  110  has a beveled edge with a cross-section that tapers from a base to an edge along which the impact absorbing members  305  are secured. For example, the modular row  110  has a pentagonal cross section where the impact absorbing members  305  are mechanically secured along an edge formed opposite the base of the pentagonal cross-section. The pentagon has two perpendicular sides extending away from the base of the pentagon to two sides that converge at an edge to which the impact absorbing members  305  are secured. As another example, the modular row  110  has a triangular cross section (e.g., isosceles triangle), and the impact absorbing members  305  are secured along an edge opposite the base of the triangular cross-section. Relative to a rectangular cross-section, the tapered cross-section reduces the mass to secure the impact absorbing members  305  to the base of the modular row  110 . The base of the modular row  110  is generally wider than an impact absorbing member  305  in order to form a shell when assembled with adjacent modular rows  110 . The general benefit of forming the base of the rows in this manner is to increase moldability of these structures. 
       Branched Impact Absorbing Members 
       [0044]      FIG. 4  is a plan view of an impact absorbing member  405  having a branched shape, in accordance with an embodiment. The impact absorbing member  405  includes a base portion  410  and two branched portions  415 . The base portion  410  and the branched portions  415  are joined at one end. Opposite ends of the branched portions  415  are secured to one of the concentric surfaces  103 , and the opposite end of the base portion  410  is secured to an opposite one of the concentric surfaces. Varying the angle between the branched portions  415  modifies the critical force to buckle the impact absorbing member  405 . For example, increasing the angle between the branched portions  415  decreases the critical force. Generally, the angle between the branched portions  415  is between 30° and 120°. The impact absorbing structure  405  may include additional branched portions  415 . For example, impact absorbing structure  405  includes three branched portions  415 , one of which is parallel to the base portion  410 . 
       Impact Absorbing Structures Including Intersecting Arches 
       [0045]      FIG. 5A  is a perspective view of impact absorbing structures  505  including intersecting arches, in accordance with an embodiment. In the illustrated example, an impact absorbing structure  505  includes two arches which each form half a circle. The portions intersect perpendicular to each other at an apex of the impact absorbing structure  505 . However, other variations are possible, such as an impact absorbing structure  505  including three arches intersecting at angles of about 60°, four arches intersecting at angles of about 45°, or a single arch. In general, having two or more intersecting arches causes the impact absorbing structure  505  to have a more uniform rigidity and yield stress from torques having different lateral directions relative to a single arch. As another example, the impact absorbing structure  505  may form a dome having a uniform resistance to torques from different lateral directions, but use of distinct intersecting arches decreases the weight of the impact absorbing structure  505 . Compared to a dome, the gaps between the arches in the impact absorbing structure  505  facilitate injection of foam or another less rigid material inside of the impact absorbing structure  505  to further dissipate energy. 
         [0046]    The ends of the arches are mechanically secured to the surface  510 , which may be a concentric surface  103  of a modular row or an inner or outer shell. The surface  510  may form an indentation  515  having a cross-sectional shape corresponding to (and aligned with) a projection of the impact absorbing structure  505  onto the surface  510 . The indentation extends at least partway through the surface  510 . For example, the indentation  515  has a cross-section of a cross to match the perpendicularly intersecting arches of the impact absorbing structure  505  secured above the indentation. When the impact absorbing structure  505  deforms as a result of a compressive force, the impact absorbing structure  505  may deflect into the indentation  515 . As a result, the impact absorbing member  505  has a greater range of motion, resulting in absorption of more energy (from deformation) and slower deceleration. Without the indentation  515 , a compressive force could cause the impact absorbing structure  505  to directly contact the surface  510 , resulting in a sudden increase in stiffness that would limit further gradual deceleration of the impact absorbing structure  505 . 
         [0047]      FIG. 5B  is a perspective view of an opposing arrangement of the impact absorbing  505  structures of  FIG. 5A , in accordance with an embodiment. An upper set of impact absorbing structures  505  is secured to an outer surface  510 A, and a lower set of impact absorbing structures  515  is secured to an inner surface  510 B. The impact absorbing structures  505  may be aligned to horizontally overlap apexes of opposing impact absorbing structures  505 , or the impact absorbing structures  505  may be aligned to horizontally offset apexes of impact absorbing structures  505  on the outer surface  510 A and inner surface  510 B. In the vertically aligned arrangement, the distance between the inner and outer surfaces is increased, which provides more room for deformation of the impact absorbing structures  505  to absorb energy from a collision. In the offset arrangement, the distance between the inner and outer surfaces  510  is reduced, and the area of contact between oppositely aligned impact absorbing structures  505  is increased. Although the outer surface  510 A and the inner surface  510 B are illustrated as being planar, they may be curved, as in a modular row or a concentric shell arrangement. In such a case, the outer surface  510 A may include more impact absorbing structures  505  than the inner surface  510 B, or the impact absorbing structures  505  of the outer surface  510 A may be horizontally enlarged relative to those on the inner surface  510 B. 
         [0048]      FIG. 5C  is a perspective view of impact absorbing structures  555  including intersecting arches  560  connected by a column  565 , in accordance with an embodiment. The intersecting arches  560  may be intersecting arches, such as the impact absorbing structures  505 . The column  565  may be similar to the impact absorbing members  105  and  305 . As illustrated, the opposite ends of a column  565  are perpendicularly connected to two vertically aligned intersecting arches  560 . Because the columns  565  are subject to different types of deformation relative to the intersecting arches (e.g., buckling and deflection), the impact absorbing structure  555  may have two or more critical forces that result in deformation of different components of the impact absorbing structure  555 . In this way, the impact absorbing structure  555  may dissipate energy from a collision in multiple stages through multiple mechanisms. In other embodiments, the impact absorbing structures  505  and  555  may include any of the impact absorbing structures described with respect to  FIGS. 6A through 8C . 
       Packed Impact Absorbing Structures 
       [0049]      FIG. 6A  is a cross-sectional view of a helmet  600  including impact absorbing structures  615  having a spherical wireframe shape, in accordance with an embodiment.  FIG. 6B  is a plan view of the impact absorbing structure  615  included in the helmet  600 , in accordance with an embodiment.  FIG. 6C  is a perspective view of the impact absorbing structure  615  included in the helmet  600 , in accordance with an embodiment. 
         [0050]    The helmet  600  includes an outer shell  605 , an inner shell  610 , and impact absorbing structures  615  disposed between the outer shell  605  and the inner shell  610 . The impact absorbing structures  615  are formed from perpendicularly interlocked rings that together form a spherical wireframe shape. Although the illustrated impact absorbing structures  615  include three mutually orthogonal rings, other structures are possible. For example, the number of longitudinal rings may be increased to improve the uniformity of the impact absorbing structure&#39;s response to forces from different directions. However, increasing the number of rings increases the weight of the impact absorbing structure  615  and decreases the space between the rings, which hinders filling an internal volume of the impact absorbing structure  615  with a less rigid material such as foam. 
         [0051]    The helmet  600  further includes a facemask  620 , which protects a face of the wearer while allowing visibility, and vent holes  625 , which improve user comfort by enabling air circulation to the user&#39;s skin. For example, the helmet  600  forms the vent holes  625  near the user&#39;s ears to improve propagation of sound waves. The vent holes  625  further serve to reduce moisture and sweat accumulating in the helmet  600 . In some embodiments, the helmet includes a screen or mesh (e.g., from metal wire) placed over a vent hole  625  to reduce penetration by particles (e.g., soil, sand, snow) and to prevent penetration by blunt objects during collisions. 
         [0052]      FIG. 7A  is a cross-sectional view of a helmet  700  including impact absorbing structures  715  having a jack shape, in accordance with an embodiment.  FIG. 7B  is a plan view of the impact absorbing structure  715  included in the helmet  700 , in accordance with an embodiment.  FIG. 7C  is a perspective view of the impact absorbing structure  715  included in the helmet  700 , in accordance with an embodiment. 
         [0053]    The helmet  700  includes an outer shell  605 , an inner shell  610 , impact absorbing structures  715  disposed between the outer shell  605  and the inner shell  610 , a face mask  620 , and vent holes  625 . As illustrated, an impact absorbing structure  715  has a jack shape formed by three orthogonally intersecting bars, which connect a central point to faces of an imaginary cube enclosing the impact absorbing structure  715 . Alternatively, the impact absorbing structures may include additional bars intersecting at a central point, such as bars that connect the central point to faces of an enclosing tetrahedron or octahedron. Compared to impact absorbing structures with a column shape, the impact absorbing structures  715  may have increased resistance to forces from multiple directions, particularly torques due to friction in a collision. 
         [0054]    The impact absorbing structures  615  or  715  may be mechanically secured to the outer shell  605 , the inner shell  610 , or both. However, mechanically securing the impact absorbing structures  615  or  715  increase manufacturing complexity and may be obviated by filling the volume between the outer shell  605  and inner shell  610  with another material. This other material may secure the impact absorbing structures  615  relative to each other and the inner and outer shells, which prevents bothersome rattling. 
         [0055]      FIG. 8A  is a cross-sectional view of a helmet  800  including impact absorbing structures  815  having a bristle shape, in accordance with an embodiment.  FIG. 8B  is a plan view of the impact absorbing structure  815  included in the helmet  800 , in accordance with an embodiment.  FIG. 8C  is a perspective view of the impact absorbing structure  815  included in the helmet  800 , in accordance with an embodiment. 
         [0056]    The helmet  800  includes an outer shell  605 , an inner shell  610 , impact absorbing structures  815  disposed between the outer shell  605  and the inner shell  610 , a face mask  620 , and vent holes  625 . As illustrated, an impact absorbing structure  815  has a bristle shape with multiple bristles arranged perpendicular to outer shell  605 , inner shell  610 , or both. The impact absorbing structure  815  further includes holes having a same diameter as the bristles. As illustrated, the holes and bristles of the impact absorbing structure are arranged in an array structure with the bristles and holes alternating across rows and columns of the array. The impact absorbing structure may include a base pad secured to the shell  605  or  610 . The base pad secures the bristles and forms the holes. Alternatively, the shells  605  and  610  serve as base structures that secure the bristles and forms the holes. Impact absorbing structures  815  on the shells  605  and  610  are aligned oppositely and may be offset so that bristles of an upper impact absorbing structure  815  are aligned with holes of the lower impact absorbing structure  815 , and vice versa. In this way, the ends of bristles may be laterally secured when the opposing impact absorbing structures  815  are assembled between the outer shell  605  and the inner shell  610 . 
         [0057]    In some embodiments, the impact absorbing structures  615 ,  715 , or  815  are secured in a ridge that protrudes from an outer shell of the helmet  100  (e.g., like a mohawk). In this way, the ridge may absorb energy from a collision before the force is transmitted to the outer shell of the helmet  100 . 
       Additional Impact Absorbing Structures 
       [0058]      FIG. 9  is a perspective view of an embodiment of an impact absorbing structure  910  having a conical structure. In the example shown by  FIG. 9 , the impact absorbing structure  910  has a circular base  915  coupled to a circular top  920  via a conical structure  925 . As shown in  FIG. 9 , a portion of the conical structure  925  coupled to the circular base  915  has a smaller diameter than an additional portion of the conical structure  925  coupled to the circular top  920  of the impact absorbing structure  910 . In various embodiments, the interior of the conical structure  925  is hollow. Alternatively, a less rigid material, such as foam, may be injected into the interior of the conical structure  925  to further dissipate energy from an impact. In various embodiments, the circular base  915  is configured to be coupled to an inner shell of a helmet, while the circular top  920  is configured to be coupled to an outer shell of a helmet, such as the helmet described above in conjunction with  FIGS. 6A, 7A, and 8A  Alternatively, the circular base  915  is configured to be coupled to an outer shell of a helmet, while the circular top  920  is configured to be coupled to an inner shell of a helmet, such as the helmet described above in conjunction with  FIGS. 6A, 7A, and 8A   
         [0059]      FIG. 10  is a perspective view of an embodiment of an impact absorbing structure  1005  having a base portion  1010  and angled support portions  1015 A,  1015 B (also referred to individually and collectively using reference number  1015 ). The impact absorbing structure  405  includes a base portion  410  and two branched portions  415 . The base portion  1010  is coupled to each of the concentric surfaces  103  further described above in conjunction with  FIG. 2 , while a support portion  1015 A has an end coupled to the base portion  1010  and another end coupled to one or the concentric surfaces  103 . In the example shown by  FIG. 10 , each base portion  1010  has two support portions  1015 A coupled to the base portion  1010  and to one of the concentric surfaces  103  and also has two additional support portions  1015 B coupled to the base portion  1010  and to the other concentric surface  103 . However, in other embodiments, the base portion  1010  has any suitable number of support portions  1015  coupled to the base portion  1010  and to one of the concentric surfaces  103 . In some embodiments, the base portion includes different numbers of support portions  1015  coupled to the base portion and to a concentric surface  103  and coupled to the other concentric surface  103 . 
         [0060]    A support portion  1015  is coupled to the base portion  1010  at an angle and is coupled to a concentric surface  103  at an additional angle. In various embodiments, the angle equals the additional angle. Varying the angle at which the support portion  1015  is coupled to the base portion  1010  or the additional angle at which the support portion  1015  is coupled to the concentric surface  103  modifies a critical force that, when applied, cause the impact absorbing member  1005  to buckle. 
         [0061]      FIG. 11  is a perspective view of an embodiment of an impact absorbing structure  1105  having a cylindrical member coupled to multiple planar surfaces  1115 A,  1115 B (also referred to individually and collectively using reference number  1115 ). In the example shown by  FIG. 9 , the cylindrical member has a vertical portion  1112  having a height and having a circular base  1110  at one end. At an opposite end of the vertical portion  1112  from the circular base  110 , multiple planar surfaces  1115 A,  1115 B are coupled to the vertical portion  1112 . Different planar surfaces  1115  are separated by a distance  1120 . For example,  FIG. 11  shows planar surface  1115 A separated from planar surface  1115 B by the distance  1120 . In various embodiments, each planar surface  1115  is separated from an adjacent planar surface  1115  by a common distance  1120 ; alternatively, different planar surfaces  1115  are separated from other planar surfaces  1115  by different distances  1120 . Each planar surface  1115  has a width  1125 , while  FIG. 11  shows an embodiment where the width  1125  of each planar surface  1115  is the same, different planar surfaces  1115  may have different widths in  1125  in other embodiments. The planar surfaces  1115  are coupled to the opposite end of the vertical portion  1112  of the cylindrical member than the circular base  1110  around a circumference of the cylindrical member. Additionally, the circular base  1110  is configured to be coupled to an outer shell of a helmet, while ends of the planar surfaces  1115 A,  1115 B not coupled to the vertical portion of the cylindrical member are configured to be coupled to an inner shell of a helmet, such as the helmet described above in conjunction with  FIGS. 6A, 7A, and 8A . Alternatively, the circular base  1110  is configured to be coupled to an inner shell of a helmet, while ends of the planar surfaces  1115 A,  1115 B not coupled to the vertical portion of the cylindrical member are configured to be coupled to an outer shell of a helmet, such as the helmet described above in conjunction with  FIGS. 6A, 7A, and 8A  In other embodiments, the circular base  1110  is configured to be coupled to a concentric surface  103  and the ends of the planar surfaces  1115 A,  1115 B not coupled to the vertical portion of the cylindrical member are configured to be coupled to another concentric surface  103 . 
         [0062]      FIG. 12  is a perspective view of an embodiment of an impact absorbing structure  1205  having a base portion  1210  to which multiple supplemental portions  1215 A,  1215 B (also referred to individually and collectively using reference number  1215 ) are coupled. Support portions  1220 A,  1220 B (also referred to individually and collectively using reference number  1220 ) are coupled to a concentric surface  103  and to a supplemental portion  1215 A,  1215 B. As shown in  FIG. 12 , an end of a supplemental portion  1215 A is coupled to the base portion  1210 , while an opposing end of the supplemental portion  1215 A is coupled to a support portion  1220 A. The support portion  1220 A has an end coupled to the opposing end of the supplemental portion  1215 A, while another end of the support portion  1220 A is coupled to a concentric surface  103 . In various embodiments, an end of the base portion  1210  and the other ends of the support portions  1220  are each coupled to a common concentric surface  103 , while an opposing end of the base portion  1210  is coupled to a different concentric surface  103 . 
         [0063]    Any number of supplemental portions  1215  may be coupled to the base portion  1210  of the impact absorbing structure in various embodiments. Additionally, the supplemental portions  1215  are coupled to the base portion  1210  at an angle relative to an axis parallel to the base portion  1210 . In some embodiments, each supplemental portion  1215  is coupled to the base portion  1210  at a common angle relative to the axis parallel to the base portion  1210 . Alternatively, different supplemental portions  1215  are coupled to the base portion  1210  at different angles relative to the axis parallel to the base portion  1210 . Similarly, each support portion  1220  is coupled to a supplemental portion  1215  at an angle relative to an axis parallel to the supplemental portion  1215 . In some embodiments, each support portion  1220  is coupled to a corresponding supplemental portion  1215  at a common angle relative to the axis parallel to the supplemental portion  1215 . Alternatively, different support portions  1220  are coupled to a corresponding supplemental portion  1215  at different angles relative to the axis parallel to the corresponding supplemental portion  1215 . 
         [0064]      FIG. 13A  is a perspective view of an embodiment of a conical impact absorbing structure  1305 . The conical impact absorbing structure  1305  has a circular base  1315  and an additional circular base  1320  that has a smaller diameter than the circular base  1315 . A vertical member  1310  is coupled to the circumference of the circular base  1315  and to a circumference of the additional circular base  1320 . Hence, a width of the vertical member  1310  is larger nearer to the circular base  1315  and is smaller nearer to the additional circular base  1320 . The circular base  1315  is configured to be coupled to a concentric surface  103 , while the additional circular base  1320  is configured to be coupled to an additional concentric surface  103 . In the example shown by  FIG. 13A , the vertical member  1310  is hollow. Alternatively, a less rigid material, such as foam, may be injected into the interior of the vertical member  1310  to further dissipate energy from an impact. 
         [0065]      FIG. 13B  is a cross-sectional view of an alternative impact absorbing structure  1330 . In the example shown by  FIG. 13B , the alternative impact absorbing structure  1330  has a circular base  1340  and an additional circular base  1345  that each have a common diameter. A vertical member  1350  is coupled to the circular base  1340  and to the additional circular base  1345 . Because the diameter of the circular base  1340  equals the diameter of the additional circular base  1345 , the vertical member  1350  has a uniform width between the circular base  1340  and the additional circular base  1345 . In the example of  FIG. 13B , the vertical member  1350  is hollow. Alternatively, a less rigid material, such as foam, may be injected into the interior of the vertical member  1350  to further dissipate energy from an impact. The circular base  1345  is configured to be coupled to a concentric surface  103 , while the additional circular base  1350  is configured to be coupled to an additional concentric surface  103 . 
         [0066]      FIG. 14  is a side view of an impact absorbing structure  1405  having arched structures  1410 A,  1410 B. In the example shown by  FIG. 4 , the impact absorbing structure  1405  has an arched structure  1410 A coupled to a concentric surface  103  at an end and coupled to another concentric surface  103  at an opposing end. Similarly, an additional arched structure  1410 B is coupled to the concentric surface  103  at an end, while an opposing end of the additional arched structure  1410 B is coupled to the other concentric surface  103 . A bracing member  1415  is positioned in a plane parallel to the concentric surface  103  and the other concentric surface  103 . An end of the bracing member  1415  is coupled to the arched structure  1410 A, while an opposing end of the bracing member  1415  is coupled to the additional arched structure  1410 B. In various embodiments, the end of the bracing member  1415  is coupled to the arched structure  1410 A at an apex of the arched structure  1410 B relative to an axis perpendicular to the bracing member  1415 . Similarly, the opposing end of the bracing member  1415  is coupled to the additional arched structure  1410 B at an apex of the additional arched structure  1410 B relative to the axis perpendicular to the bracing member  1415 . However, in other embodiments, the bracing member  1415  may be coupled to any suitable portions of the arched structure  1410 A and the additional arched structure  1410 B along a plane parallel to the concentric surface  103  and the other concentric surface  103 . 
         [0067]    Additionally, a supporting structure  1420 A is coupled to a portion of a surface of the bracing member  1415  and to an additional portion of the surface of the bracing member  1415 . Similarly, an additional supporting structure  1420 B is coupled to a portion of an additional surface of the bracing member  1415  that is parallel to the surface of the bracing member  1415  and to an additional portion of the additional surface of the bracing member  1415 . As shown in  FIG. 14 , the supporting structure  1420 A is arched between the portion of the surface of the bracing member  1415  and the additional portion of the surface of the bracing member  1415 . Similarly, the additional supporting structure  1420 B is arched between the portion of the additional surface of the bracing member  1415  and the additional portion of the additional surface of the bracing member  1415 . 
         [0068]      FIG. 15  is a perspective and cross-sectional view of an embodiment of an impact absorbing structure  1505  comprising a cylindrical structure  1510  enclosing a conical structure  1515 . In the example shown by  FIG. 15 , the impact absorbing structure  1505  has a cylindrical structure  1510  having an interior wall  1535  and an exterior wall. The cylindrical structure  1510  encloses a conical structure  1515  having a circular base  1520  at one end and an additional circular base  1525  at an opposing end. In various embodiments, the cylindrical structure  1510  and the conical structure  1515  each have different durometers, so the cylindrical structure  1510  and the conical structure  1515  have different hardnesses. Alternatively, the cylindrical structure  1510  and the conical structure  1515  have a common hardness. The additional circular base  1525  has a smaller diameter than the circular base  1520 . Additionally, the interior wall  1535  of the cylindrical structure  1510  tapers from a portion of the cylindrical structure  1510  nearest the additional circular base  1525  of the conical structure  1515  to being coupled to a circumference of the circular base  1520  of the conical structure  1515 . In some embodiments, such as shown in  FIG. 15 , a height of the conical structure  1515  is greater than a height of the cylindrical structure  1510 , so the additional circular base  1525  of the conical structure  1515  protrudes above the cylindrical structure  1510 . Alternatively, the height of the conical structure  1515  equals the height of the cylindrical structure  1510 , so a top of the cylindrical structure  1510  is in a common plane as the additional circular base  1525  of the conical structure  1515 . Alternatively, the height of the conical structure  1515  is less than the height of the cylindrical structure  1510 . As an additional example, the conical structure  1515  and the cylindrical structure  1510  have equal heights. In various embodiments, the circular base  1520  of the conical structure  1515  is configured to be coupled to an inner shell of a helmet, while the additional circular base  1525  of the conical structure  1515  is configured to be coupled to an outer shell of a helmet, such as the helmet described above in conjunction with  FIGS. 6A, 7A, and 8A . Alternatively, the circular base  1520  of the conical structure  1515  is configured to be coupled to an outer shell of a helmet, while the additional circular base  1525  of the conical structure  1515  is configured to be coupled to an inner shell of a helmet, such as the helmet described above in conjunction with  FIGS. 6A, 7A, and 8A   
         [0069]      FIG. 16  shows an embodiment of an impact absorbing structure  1605 . In the example shown by  FIG. 16 , the impact absorbing structure  1605  is a surface that undulates in a plane perpendicular to a plane including a concentric surface  103  and is coupled at one end to the concentric surface  103  and is coupled at an opposing end to an additional concentric surface  103 . For example, the impact absorbing structure  1605  has a sinusoidal cross section in a plane parallel to the plane including the concentric surface  103 . However, in other embodiments, the impact absorbing structure  1605  has any suitable profile in a cross section along the plane parallel to the plane including the concentric surface  103 . 
         [0070]      FIGS. 17A-17C  show perspective views of impact absorbing structures  1700 A,  1700 B,  1700 C comprising connected support members  1705 ,  1710 . Each support member  1705 ,  1710  has an end configured to be coupled to a concentric surface  103  and an opposing end configured to be coupled to another concentric surface  103 . A support member  1705  is coupled to the other support member  1710  by a connecting element that is in a plane perpendicular to a plane including the concentric surface  103 , or in a plane perpendicular to another plane including the other concentric surface  103 . In the example of  FIG. 17A , an impact absorbing structure  1700 A includes a rectangular structure  1715 A connecting the support member  1705  to the other support member  1710  and perpendicular to the concentric surface  103  and to the other concentric surface  103 . In various embodiments, an end of the rectangular structure  1715 A is coupled to the concentric surface  103 , while an opposite end of the rectangular structure  1715 A is coupled to the other concentric surface  103 . 
         [0071]      FIG. 17B  shows an impact absorbing structure  1700 B including an arched structure  1715 B connecting the support member  1705  to the other support member  1710 . The arched structure  1715 B is perpendicular to the concentric surface  103  and to the other concentric surface  103  and is arched in a plane that is parallel to the concentric surface  103  and to the other concentric surface  103 . In various embodiments, an end of the arched structure  1715 B is coupled to the concentric surface  103 , while an opposite end of the arched structure  1715 B is coupled to the other concentric surface  103 . 
         [0072]      FIG. 17C  shows an impact absorbing structure  1700 B including an undulating structure  1715 C connecting the support member  1705  to the other support member  1710 . The undulating structure  1715 C is perpendicular to the concentric surface  103  and to the other concentric surface  103  and includes multiple arcs in a plane that is parallel to the concentric surface  103  and to the other concentric surface  103 . For example, the undulating structure  1715 C has a sinusoidal cross section in a plane parallel to the plane including a concentric surface  103 . In various embodiments, an end of the undulating structure  1715 C is coupled to the concentric surface  103 , while an opposite end of the undulating structure  1715 C is coupled to the other concentric surface  103 . 
         [0073]    While  FIGS. 17A-17C  show examples of impact absorbing structures where a pair of support members are coupled to each other by a connecting member, any number of support members may be positioned relative to each other and different pairs of the support members connected to each other by connecting members to form structural groups.  FIGS. 18-20  show example structural groups including multiple support members positioned relative to each other with different support members coupled to each other by connecting members.  FIG. 18  shows an impact absorbing structure  1800  having a central support member  1805  coupled to three radial support members  1810 A,  1810 B,  1810 C that are positioned along a circumference of a circle having an origin at the central support member  1805 . The central support member  1800  is coupled to radial support member  1810 A by connecting member  1815 A and is coupled to radial support member  1810 B by connecting member  1815 B. Similarly, the central support member  1800  is coupled to radial support member  1810 C by connecting member  1815 C. While  FIG. 18  shows an example where the connecting member  1815 A,  1815 B,  1815 C are rectangular, while in other embodiments, the connecting members  1815 A,  1815 B,  1815 C may be arched structures or undulating structures as described in  FIGS. 17B and 17C  or may have any other suitable cross section. 
         [0074]      FIGS. 19A and 19B  show perspective views of an impact absorbing structure  1900 A,  1900 B comprising six support members coupled to each other by connecting members to form a hexagon. In the example shown by  FIG. 19A , the impact absorbing structure  1900 A has pairs of support members coupled to each other via rectangular connecting members to form a hexagon. The impact absorbing structure  1900 B shown by  FIG. 19B  has pairs of support members coupled to each other via undulating support members to form a hexagon. 
         [0075]      FIG. 20  is a perspective view of an impact absorbing structure  2000  comprising rows of offset support members coupled together via connecting members. In the example of  FIG. 20 , support members are positioned in multiple parallel rows  2010 ,  2020 ,  2030 ,  2040 , with support members in a row offset from each other so support members in adjacent rows are not in a common plane parallel to the adjacent rows. For example, support members in row  2010  are positioned so they are not in a common plane parallel to support members in row  2020 . As shown in the example of  FIG. 20 , a support member in row  2020  is positioned so it is between support members in row  2010 . Connecting members connect support members in a row  2010  to support members in an adjacent row  2020 . In some embodiments, support members in a row  2010  are not connected to other support members in the row  2010 , but are connected to a support member in an adjacent row  2020  via a support member  2015 . 
         [0076]    Although described throughout with respect to a helmet, the impact absorbing structures described herein may be applied with other garments such as padding, braces, and protectors for various joints and bones. 
       Additional Configuration Considerations 
       [0077]    The foregoing description of the embodiments of the disclosure has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure. 
         [0078]    The language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the disclosure be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosed embodiments are intended to be illustrative, but not limiting, of the scope of the disclosure.