Patent Publication Number: US-11641904-B1

Title: Helmet

Description:
BACKGROUND OF THE INVENTION 
     The present disclosure generally relates to a helmet whose purpose is to protect a wearer&#39;s head during a head impact. Extending radially outward from the wearer&#39;s head, the helmet may consist of one or multiple liner portions and one or multiple shell portions. Either way, there is typically a liner portion in contact with the wearer&#39;s head initially or during impact, that liner portion being herein defined as the subliner. The subliner may be comprised of individual subliner elements. The subliner is typically attached to an inner shell portion, the term inner having been added to unambiguously differentiate it from an outer shell portion in the case of a helmet with multiple shell portions. In helmets having just a single liner portion and a single shell portion, the liner portion would be the same as the subliner and the shell portion would be the same as the inner shell portion. In some helmets (typically hockey helmets) the inner shell portion may consist of individual shell segments. The subliner and inner shell portion together are herein defined as the helmet subliner system, and the present disclosure comprises an improved helmet subliner system, and an improved outer liner portion in the case of multiple shell helmets, to better protect the wearer from sustaining concussions and other head injuries. 
     Especially in multiple liner, multiple shell helmets, the subliner, as defined herein has been used primarily for obtaining the best fit and best comfort for the wearer. But as will be shown in this specification, the subliner, and more generally the subliner system may also be used to substantially improve the head protection performance of the helmet. The disclosure recognizes and takes advantage of the fact that all the forces that are applied to the wearer&#39;s head during a head impact are preferably applied through the subliner and its elements. 
     Recent postmortem brain investigations have found a high instance of chronic traumatic encephalopathy, or CTE, in the donated brains of deceased NFL football players, many of whom had suffered debilitating symptoms during their lifetimes, including unexplained rage, extreme mood swings, and substantial cognitive degeneration, all of which may have begun years after their football playing ended. Current research shows that CTE can almost always be traced back to long term repetitive head impacts which may include both concussive and sub-concussive impacts. It is believed those impacts would have been characterized by a high level of head angular acceleration, sometimes called rotational acceleration. The improved helmet subliner system configuration of the present disclosure is specifically designed to help reduce the level of head angular acceleration during a head impact. 
     The present disclosure generally relates to a helmet whose purpose is to protect a wearer&#39;s head during an impact. More specifically, it relates to an improved version of the helmet disclosed in U.S. Pat. No. 10,869,520, the contents of which are hereby incorporated by reference in their entirety. U.S. Pat. No. 10,869,520 discloses a subliner element to be located at the top of the head when the helmet is worn. The term subliner refers to liner elements that may come in contact with a wearer&#39;s head. The top subliner element is comprised of an energy absorbing viscoelastic foam material capable of exhibiting a compressive stress of at least 50 psi for a dynamic compression of 50%, and the element has a substantially flat lower surface which is also substantially tangent to the surface of the wearer&#39;s head beneath it when the helmet is worn. That latter requirement is to enable the liner element to slide by the wearer&#39;s head in the event of a horizontal impact while imparting little or no horizontal force to the wearer&#39;s head and to thereby substantially reduce the resulting angular acceleration (the main cause of concussions) about a horizontal axis oriented perpendicular to the impact direction. The design concept works well, but could function better where the mostly horizontal impact is accompanied by a substantial downwardly directed impact force. In that case the lower surface of the foam element may be pushed downward to at least partially conform with the curved top surface of the wearer&#39;s head, thereby precluding the element from sliding by the wearer&#39;s head without exerting a substantial horizontal force as was the desired purpose. 
     The present invention describes three alternative, structurally different designs of the top subliner element to result in, in the case of a significant horizontal impact in the presence of a significant downwardly directed impact force, a substantially lessened horizontal force being applied to the wearer&#39;s head at the place where it contacts the top subliner element. 
     SUMMARY OF THE INVENTION 
     Briefly stated, the present disclosure is directed to a helmet adapted to be worn on a head of a wearer. The head has a top area centered about a top of the wearer&#39;s head encompassing approximately 0.44 to 7 square inches. The helmet includes a subliner shell comprised of a hard impact resistant material. The shell has inner and outer surfaces. The shell is adapted to surround at least a portion of the cranial part of the wearer&#39;s head with the inner surface of the shell being spaced from the wearer&#39;s head at an initial pre-impact relative position when the helmet is worn. At least one subliner element extends from the inner surface of the shell at a location such that the subliner element is adapted to be aligned with the top area when the helmet is worn. The at least one subliner element includes a first foam pad constructed of an energy absorbing viscoelastic foam material having a top surface and a bottom surface. The top surface is attached to the inner surface of the shell. A second foam pad is constructed of an energy absorbing viscoelastic foam material that is radially partitioned into individual and independent segments. The independent segments are nested with respect to each other such that the nested segments have side surfaces in slidable direct contacting engagement with side surfaces of adjacent nested segments. The second foam pad has a top surface attached to the bottom surface of the first foam pad. A third foam pad is constructed of an energy absorbing viscoelastic foam material having a top surface and a bottom surface, with the top surface of the third foam pad being attached to the bottom surface of the second foam pad. The bottom surface of the third foam pad is a substantially flat surface which is substantially tangent to the surface of the wearer&#39;s head beneath it when the helmet is worn. 
     Briefly stated, in another aspect the present disclosure is directed to a helmet adapted to be worn on a head of a wearer. The head has a pair of eyebrows, a pair of ears and an annular headband shaped area encircling the wearer&#39;s head. The headband shaped area is approximately 0.75 to 1.25 inches wide and has a lower edge defining a plane positioned approximately 0.5 to 1.5 inches above the eyebrows and approximately 0.25 to 0.75 inches above an upper junction of the ears and the wearer&#39;s head. A top area is centered about a top of the wearer&#39;s head and encompasses approximately 0.44 to 7 square inches. A middle area of the head is defined between the headband area and the top area. The helmet includes a subliner shell comprised of a hard impact resistant material. The shell has inner and outer surfaces and is adapted to surround at least a portion of the cranial part of the wearer&#39;s head with the inner surface of the shell being spaced from the wearer&#39;s head at an initial pre-impact relative position when the helmet is worn. A subliner, at least a part of which is adapted to be in contact with the wearer&#39;s head when the helmet is worn prior to an impact and during an impact, includes a plurality of a first type of subliner elements extending from the inner surface of the shell at a location such that the first type of subliner elements are adapted to be aligned with the headband area when the helmet is worn. The first type of subliner elements are constructed of an energy absorbing viscoelastic foam material and are radially partitioned into individual and independent segments. The independent segments are nested with respect to each other with double-sided nano tape positioned therebetween such that the nested segments have side surfaces in direct contacting engagement with the nano tape. At least one of a second type of subliner element extends from the inner surface of the shell at a location such that the at least one of the second type of subliner element is adapted to be aligned with the middle area when the helmet is worn. The at least one of the second type of subliner element is constructed of a foam material. A third type of subliner element extends from the inner surface of the shell at a location such that the third type of subliner element is adapted to be aligned with the top area when the helmet is worn. The third type of subliner element includes a first foam pad constructed of an energy absorbing viscoelastic foam material having a top surface and a bottom surface. The top surface is attached to the inner surface of the shell. A second foam pad is constructed of an energy absorbing viscoelastic foam material and is radially partitioned into individual and independent segments. The independent segments are nested with respect to each other such that the nested segments have side surfaces in slidable direct contacting engagement with side surfaces of adjacent nested segments. The second foam pad has a top surface attached to the bottom surface of the first foam pad. A third foam pad is constructed of an energy absorbing viscoelastic foam material having a top surface and a bottom surface, The top surface of the third foam pad being attached to the bottom surface of the second foam pad. The bottom surface of the third foam pad is a substantially flat surface which is substantially tangent to the surface of the wearer&#39;s head beneath it when the helmet is worn. The at least one of the second type of subliner element is positioned between the plurality of the first type of subliner elements and the third type of subliner element. 
     Briefly stated, in another aspect the present disclosure is directed a helmet adapted to be worn on a head of a wearer. The head has a top area centered about a top of the wearer&#39;s head encompassing approximately 0.44 to 7 square inches. The helmet includes a subliner shell comprised of a hard impact resistant material. The shell has inner and outer surfaces. The shell is adapted to surround at least a portion of the cranial part of the wearer&#39;s head with the inner surface of the shell being spaced from the wearer&#39;s head at an initial pre-impact relative position when the helmet is worn. At least one subliner element extends from the inner surface of the shell at a location such that the subliner element is adapted to be aligned with the top area when the helmet is worn. The at least one subliner element extending from the inner surface of the shell at a location such that the subliner element is adapted to be aligned with the top area when the helmet is worn. The at least one subliner element includes a first foam pad constructed of an energy absorbing viscoelastic foam material having a top surface and a bottom surface, with the top surface being attached to the inner surface of the shell. The bottom surface is generally planar and has a first fluoropolymer coating adhered thereto. A second foam pad is constructed of an energy absorbing viscoelastic foam material having a top surface and a bottom surface. The top surface of the second foam pad is generally planar and has a second fluoropolymer coating adhered thereto. The first and second foam pads are positioned with the first and second fluoropolymer coatings in sliding facing engagement. The bottom surface of the second foam pad is a substantially flat surface which is substantially tangent to the surface of the wearer&#39;s head beneath it when the helmet is worn. 
     Briefly stated, in another aspect the present disclosure is directed to a helmet adapted to be worn on a head of a wearer. The head has a pair of eyebrows, a pair of ears and an annular headband shaped area encircling the wearer&#39;s head. The headband shaped area is approximately 0.75 to 1.25 inches wide and has a lower edge defining a plane positioned approximately 0.5 to 1.5 inches above the eyebrows and approximately 0.25 to 0.75 inches above an upper junction of the ears and the wearer&#39;s head. A top area is centered about a top of the wearer&#39;s head and encompasses approximately 0.44 to 7 square inches. A middle area of the head is defined between the headband area and the top area. The helmet includes a subliner shell comprised of a hard impact resistant material. The shell has inner and outer surfaces and is adapted to surround at least a portion of the cranial part of the wearer&#39;s head with the inner surface of the shell being spaced from the wearer&#39;s head at an initial pre-impact relative position when the helmet is worn. A subliner, at least a part of which is adapted to be in contact with the wearer&#39;s head when the helmet is worn prior to an impact and during an impact, includes a plurality of a first type of subliner elements extending from the inner surface of the shell at a location such that the first type of subliner elements are adapted to be aligned with the headband area when the helmet is worn. The first type of subliner elements is constructed of an energy absorbing viscoelastic foam material and is radially partitioned into individual and independent segments. The independent segments are nested with respect to each other with double-sided nano tape positioned therebetween such that the nested segments have side surfaces in direct contacting engagement with the nano tape. At least one of a second type of subliner element extends from the inner surface of the shell at a location such that the at least one of the second type of subliner element is adapted to be aligned with the middle area when the helmet is worn. The at least one of the second type of subliner element is constructed of a foam material. A third type of subliner element extends from the inner surface of the shell at a location such that the third type of subliner element is adapted to be aligned with the top area when the helmet is worn. The third type of subliner element includes a first foam pad constructed of an energy absorbing viscoelastic foam material having a top surface and a bottom surface. The top surface being attached to the inner surface of the shell. The bottom surface is generally planar and has a first fluoropolymer coating adhered thereto. A second foam pad is constructed of an energy absorbing viscoelastic foam material having a top surface and a bottom surface. The top surface of the second foam pad is generally planar and has a second fluoropolymer coating adhered thereto. The first and second foam pads being positioned with the first and second fluoropolymer coatings being in sliding facing engagement. The bottom surface of the second foam pad is a substantially flat surface which is substantially tangent to the surface of the wearer&#39;s head beneath it when the helmet is worn. The at least one of the second type of subliner element is positioned between the plurality of the first type of subliner elements and the third type of subliner element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed analysis of the physical principles and detailed descriptions of the preferred embodiments will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the disclosure, particular arrangements and methodologies of preferred embodiments are shown in the drawings. It should be understood, however, that the disclosure is not limited to the precise arrangements or instrumentalities shown or the methodologies of the detailed description. In the drawings: 
         FIG.  1    is a perspective side view of a wearer&#39;s head with defined areas, planes, and points in accordance with the present disclosure; 
         FIG.  2    is a perspective upper side view of a wearer&#39;s head showing the three types of subliner elements as they would be located in their respective designated areas, in accordance with a first embodiment of the present disclosure; 
         FIG.  2 A  is a perspective upper side view of a wearer&#39;s head showing the three types of subliner elements as they would be located in their respective designated areas, in accordance with a second embodiment of the present disclosure; 
         FIG.  3    is an exploded perspective view of a partitioned subliner element and its attachment to a portion of the inner shell, showing the portion of the inner shell, the hook part and the loop part of a hook and loop fastener mechanism, the partitioned segments, and an optional covering; 
         FIG.  4    is cross-sectional side view at the midsagittal plane of a wearer&#39;s head, showing the subliner elements of  FIG.  2    and the inner shell to which they are attached forming a subliner system in accordance with the present disclosure; 
         FIG.  4 A  is an exploded top perspective view of a first embodiment of a third type of subliner element in accordance with the present disclosure; 
         FIG.  4 B  is a top perspective view partially in cross section of a second embodiment of a third type of subliner element in accordance with the present disclosure; 
         FIG.  4 C  is a top perspective view partially in cross section of a third embodiment of a third type of subliner element in accordance with the present disclosure; 
         FIG.  5    is a left side elevational view showing the inner shell of  FIG.  4    positioned on a wearer&#39;s head; 
         FIG.  6    is a cross-sectional side view at the midsagittal plane of a wearer&#39;s head, of a two liner, two shell helmet embodiment, where the subliner elements and the inner shell shown in  FIG.  4    and  FIG.  5    make up a subliner system, to which is added a second liner and an outer shell, the second liner being attached to both the inner shell and the outer shell in accordance with the present disclosure; 
         FIG.  7   a    illustrates, in top plan view, a first partitioning arrangement for the second liner elements of  FIG.  6   . 
         FIG.  7   b    is a cross-sectional view of  FIG.  7   a    taken along line  7   b - 7   b.    
         FIG.  8   a    illustrates, in top plan view, a second partitioning arrangement for the second liner elements of  FIG.  6   . 
         FIG.  8   b    is a cross-sectional view of  FIG.  8   a    taken along line  8   b - 8   b.    
         FIG.  9   a    illustrates, in top plan view, a third partitioning arrangement for the second liner elements of  FIG.  6   . 
         FIG.  9   b    is a cross-sectional view of  FIG.  9   a    taken along line  9   b - 9   b.    
         FIG.  10   a    illustrates, in top plan view, a fourth partitioning arrangement for the second liner elements of  FIG.  6   . 
         FIG.  10   b    is a cross-sectional view of  FIG.  10   a    taken along line  10   b - 10   b.    
         FIG.  11   a    illustrates, in top plan view, a fifth partitioning arrangement for the second liner elements of  FIG.  6   . 
         FIG.  11   b    is a cross-sectional view of  FIG.  11   a    taken along line  11   b - 11   b.    
         FIG.  12   a    illustrates, in top plan view, a sixth partitioning arrangement for the second liner elements of  FIG.  6   . 
         FIG.  12   b    is a cross-sectional view of  FIG.  12   a    taken along line  12   b - 12   b.    
         FIG.  13   a    illustrates, in top plan view, a seventh partitioning arrangement for the second liner elements of  FIG.  6   . 
         FIG.  13   b    is a cross-sectional view of  FIG.  13   a    taken along line  13   b - 13   b.    
         FIG.  14   a    illustrates, in top plan view, an eighth partitioning arrangement for the second liner elements of  FIG.  6   . 
         FIG.  14   b    is a cross-sectional view of  FIG.  14   a    taken along line  14   b - 14   b.    
         FIG.  15   a    illustrates, in top plan view, a ninth partitioning arrangement for the second liner elements of  FIG.  6   . 
         FIG.  15   b    is a cross-sectional view of  FIG.  15   a    taken along line  15   b - 15   b.    
         FIG.  16    is a left side elevational view showing the outer shell of  FIG.  6    positioned on a wearer&#39;s head; and 
         FIG.  17    is a left side elevational view of a wearer&#39;s head showing a face guard attached to the outer shell of  FIG.  16   , and a chin strap positioned on the wearer&#39;s chin and attached to the inner shell of  FIG.  5   . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Certain terminology is used in the following description for convenience only and is not limiting. The words “lower,” “bottom,” “upper” and “top” designate directions in the drawings to which reference is made. The words “inwardly,” “outwardly,” “upwardly” and “downwardly” refer to directions toward and away from, respectively, the geometric center of the helmet, and designated parts thereof, in accordance with the present disclosure. Unless specifically set forth herein, the terms “a,” “an” and “the” are not limited to one element, but instead should be read as meaning “at least one.” The terminology includes the words noted above, derivatives thereof and words of similar import. The terms “angular acceleration” and “rotational acceleration” should be taken as synonymous from a force vector perspective. Similarly, the words “acceleration” and “deceleration” should also be taken as synonymous from a force vector perspective. It should also be understood that the terms “about,” “approximately,” “generally,” “substantially” and like terms, used herein when referring to a dimension or characteristic of a component of the disclosure, indicate that the described dimension/characteristic is not a strict boundary or parameter and does not exclude minor variations therefrom that are functionally similar. At a minimum, such references that include a numerical parameter would include variations that, using mathematical and industrial principles accepted in the art (e.g., rounding, measurement or other systematic errors, manufacturing tolerances, etc.), would not vary the least significant digit. 
     Referring now to  FIGS.  1 ,  2  and  4   , to best understand the configuration of the helmet subliner system or subliner  10 , which is a subject of this disclosure, it will be useful to first define certain areas of a potential wearer&#39;s head  12  which could come in contact with various types of subliner elements of the helmet  14 . In this regard, all the following will be defined: first area A, first plane A 1 , second plane B 1 , point b, second area B, and third area C. 
       FIG.  1    is a perspective side view of a wearer&#39;s head  12  having a pair of eyebrows  26  (only one is shown) and a pair of ears  28  (only one is shown). The head  12  includes a first area A, first plane A 1 , second plane B 1 , point b, second area B, and third area C. First area A is an annular headband shaped area encircling the wearer&#39;s head  12 . The first or headband shaped area A being approximately 0.75 to 1.25 inches wide, and preferably approximately 1.0 inch wide, and having a lower edge defining a plane positioned approximately 0.5 to 1.5 inches, and preferably approximately 1.0 inch, above the eyebrows  26  and approximately 0.25 to 0.75 inches, and preferably approximately 0.5 inches, above a location where the ears  28  join the wearer&#39;s head  12  at the top or, stated differently, an upper junction of the ears  28  and the wearer&#39;s head  12 . The first plane A 1  is a hypothetical plane defined by the lower edge of first area A. Picture second plane B 1  as a lower cover of an imaginary hard cover book being balanced horizontally atop the wearer&#39;s head  12  while the wearer&#39;s head  12  is maintained in an upright position, tilted neither right nor left, nor forward nor backward and where point b is approximately the center of the contact area between the lower cover of the imaginary book and the wearer&#39;s head  12 . Notice that first plane A 1  is tilted upward in the forward direction (the direction toward the face of the wearer) relative to second plane B. In  FIG.  1   , the second plane B 1  is shown as transparent so that the contact area with the wearer&#39;s head  12 , point b, is apparent. The second or top area B is formed by a planar projection of an approximate 2-inch diameter circle (not shown) formed in the second plane B 1  centered about point b onto the wearer&#39;s head. That is, the second area B is generally circular and is centered about a top of the wearer&#39;s head  12  and extends 0.75 to 3 inches, and preferably 2 inches, in diameter in all lateral directions. As will be discussed, the second area B needn&#39;t be 2 inches in diameter, nor even circular. That is, the second area B can range from 0.44 to 7 square inches, or preferably 3.14 square inches. The third or middle area C is the area on the wearer&#39;s head  12  between first area A and second area B. 
     Referring again to  FIGS.  1 ,  2  and  4    and as will be described in detail in subsequent sections of the specification, subliner elements of a first type  16  are to be located in the first area A; subliner elements of a second type  18  are to be utilized in third area C, and a subliner element of a third type  20  is to be used in second area B. Each type of subliner element  16 ,  18 ,  20  has its own specific physical characteristics in accordance with the purpose of the disclosure which is to be able to reduce the level of head angular acceleration imparted to a wearer&#39;s head  12  during a head impact, regardless of the location or direction of the impact. Each of the subliner elements  16 ,  18 ,  20  is to be attached to an inner surface  22  of the inner shell  24  of the helmet  14 , preferably utilizing a commonly employed hook and loop type of fastener arrangement which allows for the simple assembly of, and changeout of, individual subliner elements  16 ,  18 ,  20  during a fitting process, with each subliner element  16 ,  18 ,  20  being positioned and sized in its thickness direction to best fit the size and shape of a wearer&#39;s head  12 . It will be appreciated by one skilled in the art, that other fastening elements could be used to releasably secure the subliner elements  16 ,  18 ,  20  to the inner surface  22  of the inner shell  24  of the helmet  14 , such as a releasable adhesive (not shown). 
       FIG.  2    is a perspective upper side view of a wearer&#39;s head  12  showing the first, second and third types of subliner elements  16 ,  18 ,  20  as they would be located in their respective designated areas shown in  FIG.  1   , in accordance with a first embodiment of the present disclosure. The individual subliner elements  16 ,  18 ,  20  are not attached to the wearer&#39;s head  12  (as could be falsely assumed from  FIG.  2   ) but are merely illustrated in the figure where they would be located with respect to the wearer&#39;s head  12  when the helmet  14  is worn. Typically, they would be attached to the inner surface  22  of the inner shell  24  of the helmet  14 , as shown in  FIG.  4   , preferably utilizing a commonly employed hook and loop type of fastener arrangement, describe below. The upper side viewpoint enables a fuller view of a first embodiment of a subliner element of the third type  20 , which is preferably disc or oval shaped, oriented generally in the second plane B 1 , and is centered about point b at the top, or crown, of the head  12 . Subliner element of the third type  20  has a flat (or nearly flat), horizontal (or nearly horizontal), lower surface  20   a  which may be either initially in contact with the wearer&#39;s head  12  or slightly spaced therefrom but may come into contact with the wearer&#39;s head  12  during an impact. Subliner element of the third type  20  is shown here as a circular disc having a two-inch diameter to accommodate any misalignment of the center of the disc with the initial actual point of contact with a wearer&#39;s head  12  and to accommodate lateral displacements between the inner shell  24  and the wearer&#39;s head  12  during an impact. In general, the subliner element of the third type  20  need not be circular, but it may be of any suitable contiguous shape typically having that approximate area or greater. The important thing is that its lower surface  20   a  be of sufficient area to enable the accommodations described above, and that it be predominately flat and horizontal such that it is substantially tangent to the surface of the wearer&#39;s head  12  beneath it when the helmet  14  is worn. 
     To be able to appreciate why the lower surface  20   a  of subliner element of the third type  20  is preferred to be flat and horizontal, one may perform a simple experiment with one&#39;s own hand and one&#39;s own head. First, using one&#39;s hand, firmly cup the top of one&#39;s head. Then while still firmly cupping the head, forcefully move the cupping hand&#39;s forearm forward and backward, and side to side, and notice how the head is forced into violent motion likely involving significant head angular accelerations. Next, repeat the experiment while the hand is held flat and horizontal. The result: 
     almost no forced motion of the head, and thus no head angular acceleration. 
     Referring now to  FIGS.  2 ,  4  and  4 A , the subliner element of the third type  20  is comprised of a first foam pad  110  constructed of an energy absorbing viscoelastic foam material having a top surface  110   a  and a bottom surface  110   b , the top surface  110   a  being attached to the inner surface  22  of the shell  24 . The first foam pad  110  is generally disk shaped and preferably made of relatively stiff, very energy absorbent, viscoelastic foam material, capable of exhibiting a compressive stress of 20 psi for a static compression of 50% and at least 50 psi for a dynamic impact type compression of 50%, for example a vinyl nitrile foam such as IMPAX®, VN600, VN740, or VN1000 by Dertex Corporation, or a polyurethane foam such as LAST-A-FOAM®, FP 8015 by General Plastics Manufacturing Company. 
     The subliner element of the third type  20  further includes a second foam pad  112  being constructed of an energy absorbing viscoelastic foam material that is the same as the material in the first foam pad  110 . The second foam pad  112  is radially partitioned into individual and independent segments  114 . The independent segments  114  are nested with respect to each other such that the nested segments  114  have side surfaces  116  in slidable direct contacting engagement with side surfaces  116  of adjacent nested segments  114 . The second foam pad  112  has a top surface  112   a  attached to the bottom surface  110   b  of the first foam pad  110 . 
     The segments  114  are in the form of a plurality of side-by-side, vertically oriented, slender foam columns or segments  114  that have substantially less sidewise stiffness than a solid foam portion. The resulting sidewise stiffness is lessened if the columns  114  are made longer, or made more slender even though that results in more columns  114  to fill the same area. The foam material of the segments  114  is preferably the same material as the rest of the first foam pad  110 , although another foam material may be substituted if the other material still is capable of exhibiting a compressive stress of at least 50 psi for a dynamic compression of 50%. To make sure the segments  114  stay together during a compressive impact the second foam pad  112  and/or segments  114  are tightly surrounded by a generally inelastic cord made of a high strength, low elongation material such as KEVLAR®. The second foam pad  112  has a length or height and the cord  118  is positioned generally in the middle of the length or height. 
     The subliner element of the third type  20  further includes a third foam pad  120  constructed of an energy absorbing viscoelastic foam material which is the same material as the first foam pad  110 . The third foam pad  120  is generally disk shaped and similarly shaped to the first foam pad  110 . The third foam pad  120  has a top surface  120   a  and a bottom surface  120   b . The top surface  120   a  of the third foam pad  120  is attached to the bottom surface  112   b  of the second foam pad  112 . The bottom surface  120   a  of the third foam pad  120  is a substantially flat surface which is substantially tangent to the surface of the wearer&#39;s head  12  beneath it when the helmet  14  is worn. The bottom surface  120   a  of the third foam pad  120  forms the horizontal lower surface  20   a , described above. The first, second and third foam pads  110 ,  112  and  120  are preferably secured together using a suitable adhesive that works well with foam. That is, the adhesive is preferably flexible in its cured condition to accommodate any stretching or compressing of the foam materials during an impact, as is well understood by those of ordinary skill in the art. Preferably, the slender foam columns  114  in totality enable a sidewise relative displacement between the first and second foam pads  110 ,  112  of at least one-half inch in response to a sidewise force of less than 100 pounds. After an impact, the slender foam columns  114  are able to return the first and second foam pads  110 ,  112  to their pre-impact relative position. 
     Referring now to  FIG.  4 B , there is shown a second embodiment of a subliner element of the third type  20 ′, which includes a first foam pad  110 ′ constructed of an energy absorbing viscoelastic foam material having a top surface  110   a ′ and a bottom surface  110   b ′. The top surface  110   a ′ is attached to the inner surface  22  of the shell  24 , as described above. The bottom surface  110   b ′ is generally planar and has a first fluoropolymer coating or layer  122  adhered thereto. 
     The second embodiment of a subliner element of the third type  20 ′ further includes a second foam pad  112 ′ constructed of an energy absorbing viscoelastic foam material having a top surface  112   a ′ and a bottom surface  112   b ′. The top surface  112   a ′ of the second foam pad  112 ′ is generally planar and has a second fluoropolymer layer or coating  124  adhered thereto. The first and second foam pads  110 ′,  112 ′ being positioned with the first and second fluoropolymer coatings  122 ,  124  in sliding facing engagement. The bottom surface  112   b ′ of the second foam pad  112 ′ is a substantially flat surface which is substantially tangent to the surface of the wearer&#39;s head  14  beneath it when the helmet  12  is worn. The bottom surface  112   a ′ of the second foam pad  112 ′ forms the horizontal lower surface  20   a , described above. Both the first and second foam pads  110 ′,  112 ′ are generally disk shaped. 
     Each fluoropolymer layer  122 ,  124  is pre-treated on just one side to enable it to be strongly adhered to another surface. The adhering agent is an adhesive which is flexible in its cured condition to be able to accommodate any stretching or compressing of the foam materials during an impact. The first foam pad  110 ′ has a first side surface  110   c ′ extending between the top and bottom surfaces  110   a ′,  110   b ′. The second foam pad  112 ′ has a second side surface  112   c ′ extending between the top and bottom surfaces  112   a ′,  112   b ′. A first rib or band  126  is secured to the first side surface  110   c ′ of the first foam pad  110 ′. A second rib or band  128  is secured to the second side surface  112   c ′ of the second foam pad  112 ′. The upper and lower ribs  126 ,  128  surround the first foam pad  110 ′ and the second pad  112 ′, respectively, at near the mid height of each first side surface  110   c ′ and second side surface  112   c ′. Each rib  124 ,  126  is preferably constructed of a polymeric material and has several holes  130  to accommodate metal pins  132  which are long enough to hold each of the ribs  126 ,  128  in place by being embedded in the foam. Preferably there would be between six and sixteen holes  130  and pins  132  to properly secure each rib  126 ,  128  to the underlying foam portion. 
     A biasing element extends between the first and second ribs  126 ,  128  to force the first and second fluoropolymer coatings  122 ,  124  toward each other. That is, preassembled onto the ribs  126 ,  128  before they are pinned into place are a plurality of small elastomer bands  134  spaced around periphery of the first and second foam pads  110 ′,  112 ′. Preferably there would be a total of eighty to one hundred sixty elastomer bands  134  distributed around the circumference, each one being stretched between the upper and lower ribs  126 ,  128 . And preferably, each elastomer band  134  is pre-twisted one time between the upper and lower ribs  126 ,  128  so that the two free lengths of each elastomer band  134  are equal. The free length being that section of an elastomer band  134  stretched around the upper and lower ribs  126 ,  128 . The first and second fluoropolymer coatings  122 ,  124  are biased toward each other by a force applied to the first and second foam pads  110 ′,  112 ′ as result of the elastomer bands  134 . 
     The material of the elastomer band  134  should have an elastic elongation capability of greater than 100% to be able to elastically accommodate the required stretch of their free lengths as the first and second fluoropolymer coatings  122 ,  124  slide relative to each other in response to an impact. Then after an impact the elastomer bands  134  return the first and second foam pads  110 ′,  112 ′ to their pre-impact relative position. 
     Referring now to  FIG.  4 C , there is shown a third embodiment of a subliner element of the third type  20 ″. The third embodiment of the subliner element of the third type  20 ″ is identical to the second embodiment of the subliner element of the third type  20 ′, except that the plurality of elastomer bands  34  have been replaced with a plurality of spring elements  136  described in more detail below. Accordingly, only the differences between the third embodiment of the subliner element of the third type  20 ″ and the second embodiment of the subliner element of the third type  20 ′ will be described, with like double prime element numbers being used for the third embodiment of the subliner element  20 ″. The spring element  136  is preferably in the form of a generally V-shaped wire. The spring elements  136  shown in  FIG.  4 C  are shown in an installed, mostly unstressed configuration. Each spring element  136  would be typically comprised of metal or polymer plastic. If metal, it could be hardened stainless steel having a yield strength of greater than 200,000 psi. If polymer plastic, it could be a polymer having very good spring properties such as acetal. The spring elements  136  illustrated in  FIG.  4 C  exhibit a high yield strength and are constructed of 10 mil diameter stainless steel spring having a length of approximately 1 inch in its long dimension. Each spring element  136  has two flattened and curved hook-like terminal ends  136   a  that fit securely behind the upper and lower ribs  126 ″,  128 ″ with the spring elements  136  extending outward radially. Typically, there could be a total of up to one hundred eighty or less spring elements  136 . The spring elements  136  elastically deform as the as the first and second fluoropolymer coatings  122 ,  124  slide relative to each other in response to an impact. Then after an impact the spring elements  136  return the first and second foam pads  110 ′,  112 ′ to their pre-impact relative position. 
     The subliner element of the third type  20  should be thick enough not to compress all the way to its full densification condition under a peak normal impact force which could easily reach, and possibly even exceed, a thousand pounds. Although the weight of a full helmet would likely be substantially less than that (being typically under five pounds), if all the helmet weight were to be required to be supported by the subliner element of the third type  20 , with its high dynamic stiffness designed to accommodate a dynamic force of over a thousand pounds, the supporting area around point b for a static force of just five pounds could be so small that the supporting pressure could be uncomfortably high for the wearer were it not for the subliner elements of the second type  18 , shown in third area C. 
     Subliner elements of the second type  18 , located in third area C, would preferably be made of a much more compliant material than that used for the subliner element of the third type  20 , preferably at least five times more compliant and perhaps more than an order of magnitude more compliant than the stiffer materials recommended for subliner element of the third type  20 . Such a material could be an extra soft polyurethane foam such as LAST-A-FOAM®, EF-4003 by General Plastics Manufacturing Company, or EZ-Dri foam by Crest Foam Industries, both having, a relatively flat static and dynamic compression stress vs. deflection characteristic (the former 2.6 psi at 10%, 2.7 psi at 20%, 2.8 psi at 30%, 3.0 psi at 40%, and 3.4 psi at 50% and the latter 0.3 psi at 10%, 0.35 psi at 20%, 0.4 psi at 30%, 0.45 psi at 40% and 0.55 psi at 50%), so when incorporating the proper total area to accomplish the function of supporting the full weight or nearly the full weight of the helmet with the latter material enabling about five times the support area for extreme comfort, the exact location and thickness of the subliner elements of the second type  18  would not be that critical for the subliner elements of the second type  18  to be able to successfully support all, or almost all, of the weight of the helmet, yet contribute very little side force to the wearer&#39;s head  12  during an impact. However, the second type of subliner elements  18  are preferably positioned generally equidistantly about and between the first and third type of subliner elements  16 ,  20  in the third area C. 
       FIG.  2 A  shows a second embodiment of the present disclosure wherein there is at least one of a second type of subliner element  18 . That is, instead of a plurality of the second type of subliner elements  18  as shown in  FIG.  2   , the second type of subliner elements  18  in accordance with the second embodiment are instead formed as a single annular ring  18 ′. Using a single annular ring  18 ′ has the advantage of easier assembly and greater simplicity. Otherwise, all other elements of the subliner system  10  of the second embodiment are identical to the first embodiment. 
       FIG.  1    schematically shows the cervical spine  13  and its seven cervical vertebrae labeled Atlas (C1), Axis (C2), C3, C4, C5, C6 and C7. For both centered (directed toward the center of gravity of a wearer&#39;s head) and non-centered impacts having a large horizontal force component, almost all the side forces (and torques) that would be imparted to a wearer&#39;s head  12  during an impact would be imparted through the subliner elements of the first type  16 , which would be located, or substantially located, in first area A and generally evenly distributed/spaced thereabout. First area A places the point of application of these impact forces as close as possible to the head&#39;s two natural pivot points for angular acceleration: a lower pivot point  12   a  where the C7 cervical vertebrae (which can be located by the prominent bone at the base of the back of the neck) meets the Ti thoracic vertebrae, and an upper pivot point  12   b  where the C1 cervical vertebrae (the atlas bone) meets the paired occipital condyle projections of the skull to enable forward and backward rotation (a “yes” motion) of the head and where the atlas bone meets the C2 cervical vertebrae (the axis bone) enabling axial rotation (a “no” motion) and side-to-side rotation of the head, this latter pivot being located approximately just above and slightly in front of the ear lobes. Thus, all the head angular accelerating torques imparted to the user&#39;s head during an impact would be kept as small as possible for a given force as a result of this lowest practical positioning of subliner elements of the first type  16 . 
     As stated previously, each embodiment of the subliner element of the third type  20 , due to its flat horizontal lower surface  20   a , typically does not impart a significant horizontal force to the wearer&#39;s head  12 . The following description of the first embodiment of the subliner element of the third type  20 , is equally applicable to the second and third embodiments of the subliner element of the third type  20 ′  20 ″. There may be certain impacts during which the lower surface  20   a  of the subliner element of the third type  20  would not remain flat but instead would tend to cup around the surface of the wearer&#39;s head  12 . One such type of impact is obvious: a direct downward impact to the crown, or top, of the helmet  14 , centered toward the center of gravity (e.g.) of the wearer&#39;s head  12 . Although that type of impact would result in cupping the lower surface of subliner element of the third type  20  around the wearer&#39;s head  12 , little or no horizontal force would be imparted to the wearer&#39;s head  12 . 
     Another impact case that could cup the lower surface of the subliner element of the third type  20  might be a downward impact to the top of the helmet at a point located away from the crown and generally directed toward the body of the wearer. Picture a running back diving over the goal line, his helmet getting struck in midair by the shoulder pad of a linebacker diving the other way to stop him. Here, in addition to a significant downward force through the subliner element of the third type  20  (downward here meaning downward toward the body of the running back), there could be a not-insignificant horizontal force (horizontal here meaning horizontal relative to the body of the running back) imparted to the running back&#39;s head through subliner element of the third type  20 , as well as through the subliner elements of the first type  16 ; for the most part the former would tend to rotate point b on the running back&#39;s head about the aforementioned upper pivot point toward the impact location, while the latter would tend to rotate point b about the aforementioned lower pivot point away from the impact location. So even in this case where the subliner element of the third type  20  cannot avoid imparting a horizontal (sideways) force, the structure of the total subliner system  10  still tends to cancel the above two rotational head motions and thereby reduce the resultant angular acceleration of the wearer&#39;s head  12 . 
     Further reductions of imparted torque levels can be achieved by lowering the impact force levels, which can be accomplished by a proper choice of material for the subliner elements of the first type  16 , and by including specific structural features in the subliner elements of the first type  16 . Especially during an impact involving mostly a horizontal force component, only about one third of the subliner elements of the first type  16  (those located in the wide general region beneath the impact point) would be imparting most of the side normal force and side tangential force to the wearer&#39;s head  12  since the remaining subliner elements of the first type  16  would have tended to move away from the wearer&#39;s head  12  during the impact as the force-imparting subliner elements of the first type  16  compress and/or flex as a result of the high impact forces. The force levels could be of the same order of magnitude as those potentially experienced by the subliner element of the third type  20  (up to, and perhaps even more than a thousand pounds), and so the same energy absorbing viscoelastic foam materials cited for subliner element of the third type  20  would be in order for subliner elements of the first type  16 , where their high energy absorption capability will help reduce the level of the high impact forces. The radial (thickness) dimension of the subliner elements of the first type  16  should be of sufficient length and have sufficient area to be able to avoid full densification at the maximum expected peak dynamic impact force, which could still be in the thousand-pound range for the total aggregate number of forces imparted on the subliner elements of the first type  16 . On average the radial thickness of the subliner elements of the first type  16  would be approximately 0.25 to 1.25 inches, and preferably 0.75 inches in a two shell case, and approximately 1.0 to 2.0 inches, and preferably 1.5 inches in a single shell case. 
     In a preferred embodiment, to increase lateral compliance to help further reduce the imparted tangential side forces, the subliner elements of the first type  16  may be partitioned into multiple segments or columns which emanate in a substantially perpendicular direction from the inner surface  22  of the inner shell  24 . The partitioning may be in the form of like-shaped segments having a particular cross-sectional shape, or it could be in the form of different shaped segments, as for instance an outer square cross-sectional shaped segment  36  having a centered circular cutout  38 , along with a circular cross-sectional segment  40  to fill the circular cutout space, see  FIG.  3   . In order to best achieve the goal of reduced imparted side forces, the side surfaces of the partitioned side-by-side segments should be at least partially able to frictionally slide relative to each other in the segments&#39; general radial direction. More particularly, double-sided nano tape  39  is preferably positioned between the nested side surfaces such that the side surfaces are in direct contacting engagement with the nano tape  39 . Thus, when adjacent side surfaces slide relative to each other during an impact, the highly viscous nano tape gets sheared across its thickness and additional energy is absorbed. It will be understood by those skilled in the art that nano tape  39  may be any nano tape which is commercially available. In general, nano tape  39  is an elastic tape that includes a nanofiber or nanotube structure which adheres to an adjacent surface due to Van der Waals forces. In one embodiment, the nano tape  39  is a comprised of carbon nanotube arrays provided on a backing layer formed of a flexible polymer, such as polyurethane, with Van der Waals interactions occurring between the carbon nanotube arrays and individual nanotubes and the adjacent surface. The nano tape is in the range of 0.5 to 2.0 mm thick and most preferably 1.0 mm thick. To assemble the subliner element of the first type  16  shown in  FIG.  3   , the nano tape  39  is wrapped around the circular cross-sectional segment  40  which is then inserted into the circular cutout  38  such that that nano tape  39  is positioned therebetween, as described in more detail below. The segment&#39;s generally parallel partitioned surfaces cannot be exactly radial from the standpoint of the wearer&#39;s head  12  due to the width of the partitioned element, but they are substantially radial. The partitioning or segmenting might be implemented using a simple “cookie cutter” approach. Other examples of partitioning subliner elements that could be used for the first type of subliner element  16  are described below in  FIGS.  7   a - 7   b  through  15   a - 15   b   . These and their subsets, are themselves a small subset of all of the partitioning configurations that may be utilized. 
       FIG.  3    is an exploded perspective view of a partitioned subliner element of the first type  16  and its attachment to a portion of the inner surface  22  of the inner shell  24 , showing the portion of the inner shell  24 , the hook part  30  and the loop part  32  of a hook and loop fastener mechanism of a type in common usage today for such applications, along with an optional covering  34  over the subliner element of the first type  16 . Any of the subliner elements, of any of the three subliner element types  16 ,  18 ,  20  may include a full covering  34  formed from a fabric or a film  34  to improve the comfort of the wearer, to improve the durability of the subliner element types  16 ,  18 ,  20 , or to improve the functioning of the subliner element types  16 ,  18 ,  20 , the latter possibly including, but not being limited to, its ability hold partitioned columns of a subliner element type  16 ,  18 ,  20  in place, its ability to protect against moisture and contaminants, its ability to improve air flow, and its ability to improve moisture dissipation. The optional covering  34  need not be full as shown but may be partial if the circumstances warrant. The fabric of choice may be any of a wide range of suitable fabrics, while the film of choice could be any suitable polymer or elastomer film having a suitable thickness for the application. 
     Referring still to  FIG.  3   , the subliner element of the first type  16  preferably includes a generally inelastic cord  41  surrounding the subliner element of the first type  16 . The subliner element of the first type  16  has a length extending away from the inner surface  22 . The inelastic cord  41  is positioned generally in the middle of the length. The inelastic cord  41  is preferably constructed of KEVLAR®, but other like materials could be substituted. The purpose of the inelastic cord  41  is to prevent the subliner element of the first type  16  from bulging in the center area to ensure that the circular cross-sectional segment  40  and the centered circular cutout  38  maintain good surface to surface contact with the nano tape  39 . While the inelastic cord  41  is shown being positioned directly around the outer square shaped the segment  36 , it could also be positioned about the cover  34 . 
       FIG.  4    is a cross-sectional side view located at the midsagittal plane of the wearer&#39;s head  12  showing the three types of subliner elements  16 ,  18 ,  20  as located in  FIG.  2    and the inner shell  24  to which they are attached. The inner shell  24  may be part of a single liner, single shell helmet  14  as illustrated in the figure, or it may be part of a multiple liner, multiple shell helmet, as discussed in more detail below. The relative size of the inner shell  24  shown in  FIG.  4    at the lower end of the indicated radial thickness range would be consistent with the former case if the helmet were for example an equestrian helmet or a ski helmet, and the relative size of the inner shell shown in  FIG.  4    would also be consistent with the latter case if the helmet were for example a football helmet or a motorcycle helmet. A football helmet or a motorcycle helmet of the single liner, single shell type would typically have a larger subliner system  10  at the higher end of the indicated radial thickness range, which in that case would also be the outer shell. Thus, in a football helmet or motorcycle helmet of the single liner, single shell type embodiment, the radial spacing of the inner shell  24  from the head  12  would typically be greater than that shown in  FIG.  4    and the subliner elements of the first, second and third types  16 ,  18 ,  20  would accordingly have a greater radial dimension. 
     With continued reference to  FIG.  4   , the inner surface  22  of the inner shell  24  above subliner element of the third type  20  is shown to have a flat horizontal surface  42  rather than a concave surface. The inner shell  24  may be molded that way to achieve the flat horizontal surface  42 . The flat horizontal surface  42  is not absolutely necessary but it is preferred to enable subliner element of the third type  20  to be flat on its upper surface as well as its lower surface  20   a , which helps to assure a horizontal lower surface  20   a , and makes it simpler and more controllable to determine, select, and properly align and apply a proper thickness subliner element of the third type  20  so that it&#39;s lower surface  20   a  remains horizontal and preferably barely touches the wearer&#39;s head  12 . As shown in  FIG.  4   , the two cross-sectioned subliner elements of the second type  18  are shown in the third area C, properly radially compressed, as would be all of the other subliner elements of the second type  18  not shown in the cross-section, when all are supporting the full weight of the helmet, even though the full helmet with all its potential parts, including a potential face guard and a potential chin strap or jaw strap system, is not shown in  FIG.  4   . Finally, the subliner elements of the first type  16  in the first area A each have a thickness to yield a snug but not uncomfortable fit with the wearer&#39;s head  12 . 
       FIG.  5    is a left side elevational view of the wearer&#39;s head  12  showing the inner shell  24  of  FIG.  4    located over the wearer&#39;s head  12  with all the subliner elements of the first, second and third type  16 ,  18 ,  20  positioned as shown in phantom and as in  FIG.  2   ; all of the subliner elements of the first, second and third type  16 ,  18 ,  20  being attached to the inner surface  22  of the inner shell  24 , typically by the easy-on, easy-off, hook and loop fastener mechanism  30 ,  32  shown in  FIG.  3   . The easy-on, easy-off capability helps in being able to customize the helmet for an individual wearer. The potential materials to be used for the inner shell  24  would depend upon which embodiment it is being used in. In the single liner, single shell helmet embodiment the inner shell  24  (which is now also the outer shell) must be able to handle a direct impact, so an impact resistant material such as polycarbonate or high impact ABS would be appropriate. In the multiple liner, multiple shell helmet embodiment described in more detail below, the inner shell  24  need not handle a direct impact, but it still would need to be able to handle high forces so a high strength polymer composite containing either glass fibers, carbon fibers, or KEVLAR® fibers (commonly understood as heat-resistant and strong synthetic fibers) or a composite utilizing a combination of different fibers could be appropriate. Also, for this embodiment, the inner shell  24  could be constructed of a thin metal, such as stainless steel or an aluminum alloy (either perforated, or not perforated), and in large quantities could be fabricated by pressing it to shape in a die with a large machine press. Such a thin metal shell, perhaps a thirty-second of an inch or less in thickness, could weigh even less than a comparable strength polymer composite shell. 
       FIG.  6    is a cross-sectional side view located at the midsagittal plane of a wearer&#39;s head  12 , showing a two liner, two shell, helmet  14  embodiment of the present disclosure.  FIG.  6    shows the subliner system  10  of  FIG.  4   , plus a second or outer liner  44  and a second or outer shell  46  which together form an outer shell system  48 . Five outer liner elements  50  are shown in the second liner  44  because they cross the midsagittal plane. Typically, there may be ten to fifteen additional liner elements  50  in the second liner  44  which are not shown in  FIG.  6    because they do not cross the midsagittal plane. That would add up to a likely total of fifteen to twenty total liner elements  50  in the second liner  44 , spread out more or less equidistantly throughout the available space between the inner shell  24  and the second or outer shell  46 . 
     All the liner elements  50  of the second liner  44  are firmly attached to both the outer surface of the inner shell  24  and the inner surface of the outer shell  46 . By contrast, subliner elements of the first, second and third types, 16, 18, 20 in the subliner system  10  can only be attached to the inner shell  24  (they cannot be attached to a wearer&#39;s head). The firm attachment of the liner elements  50  of the second liner  44  to both the inner and outer shells  24 ,  46  enables liner elements  50  to experience not just high compression forces, but high shear forces and high tensile forces as well. As a result, the attachment requirement here is beyond the capability of a standard hook and loop fastener and is more in the realm of a high strength, wide temperature range, flexible adhesive, such as LOCTITE® 4902, or LOCTITE® Plastic Bonder, both by Henkel Corporation. The former is a one-part adhesive, the latter a two-part adhesive, and both are quick curing. 
     These flexible, high strength attachments make it possible for all the liner elements  50  of the second liner  44  to participate in mitigating any impact to the wearer&#39;s head  12 , regardless of the impact&#39;s location or direction. That mitigation is accomplished through the widespread positioning of the liner elements  50  and their ability to efficiently absorb energy in three different modes: compression, shear, and tension. For example, for any centered impact the liner elements  50  of the second liner  44  generally located in the region beneath the impact will experience compression, those located to the side of the impact will experience shear, and those located opposite the impact will experience tension, while those located in between will experience some combination of compression, shear, and tension. For any non-centered impact most of the liner elements  50  of the second liner  44  will experience a higher degree of shear. Because every impact is different in its location and direction, each liner element  50  in the second liner  44  must be able to absorb energy at all the expected possible levels of compression, shear, and tension, and combinations thereof. 
     Furthermore, in order to even be in a position of optimally absorbing energy, each liner element  50  of the second liner  44  must become deformed during an impact to its full extent by the outer shell  46 , not just those liner elements  50  beneath the impact, but those to the side of the impact, and those opposite the impact as well, and the outer shell  46  must remain rigid enough during the impact to be able to accomplish that. Because the outer shell  46  is relatively thin and typically made of a polycarbonate or high impact ABS, this requires that the outer shell  46  be rigidized, especially near its opening to accommodate a wearer&#39;s head  12 , which is the place where it is the weakest. Notice in the figure, that there are two molded-in internal rings  52  near the opening to accomplish the rigidizing, but other rigidizing approaches such as severe contouring or metal banding (not shown) would also be acceptable. 
     Achieving the optimum energy absorption by all the liner elements  50  of the second liner  44  also requires they be fabricated of a material having an inherent high energy absorbing capability, and that the material also have a proper level of dynamic stiffness for the total second liner element  50  footprint area. To meet these criteria, the liner elements  50  of the second liner  44  may be fabricated from the same list of materials recommended for subliner elements of the first and third types  16 ,  20 , the list including: a vinyl nitrile foam such as IMPAX® VN600, VN740, or VN1000 by Dertex Corporation, or a polyurethane foam such as LAST-A-FOAM® FP 8015 by General Plastics Manufacturing Company. However, in block form, each material likely presents too much dynamic stiffness in shear as compared to its dynamic stiffness in compression and tension. So to reduce a second liner element&#39;s dynamic stiffness in shear, without at the same time reducing its dynamic stiffness in compression or tension, partitioning of each liner element  50  into discrete adjacent segments is preferred, somewhat similar to what has been previously discussed for subliner elements of the first type  16 , but even more so for the second liner elements  50  because the potential shear levels experienced by the second liner elements  50  are greater. 
     The cross-sectioning of the second liner elements  50  in  FIG.  6    reveals each element to be partitioned into five equal segments  50   a ,  50   b ,  50   c ,  50   d ,  50   e . However, one skilled in the art will understand that there are several partitioning possibilities, all of which could be acceptable options if they can achieve the proper level of reduction in the total shear force as compared to the total compression and tensile forces. 
       FIGS.  7   a  through  15   a    show nine such partitioning possibilities, illustrated in plan view (from the viewpoint of the outer shell  46 ) to be able to see what they actually could represent. Cross-sectional views in  FIGS.  7   b  through  15   b    show the same sectional view as what is shown in  FIG.  6   . However, even these nine are still an extremely reduced sample of what may be possibly used as partitioning arrangements for the second liner elements  50 .  FIGS.  7   a  and  7   b    show twenty-five equal square shaped segments or foam columns  54  arranged in a 5×5 square array. That is, the foam columns  54  form a plurality of generally radially oriented side-by-side flexible individual and independent foam columns or segments  54 . The columns or segments  54  are preferably formed entirely of foam and having a top surface  54   a , a bottom surface  54   b , and foam side surfaces  54   c  where the top surface  54   a  is directly attached to the inner surface of the outer shell  48  and the bottom surface is directly attached to the outer surface of the inner shell  24 . The foam side surfaces  54   c  of adjacent columns or segments  54  are positioned side-by-side with respect to each other preferably with double-sided nano tape  39  positioned therebetween such that the segments  54  are nested in slidable direct contacting frictional engagement with the nano tape  39 .  FIGS.  8   a  and  8   b    show a liner element  50  having an outer circumferential square wall  56  and an inner square cutout  58 , filled with nine equal square shaped segments arranged in a 3×3 square array. Nano tape  39  is positioned between the outer circumferential square wall  56  and the nine equal square shaped segments as well as between the nine equal square shaped segments themselves.  FIGS.  9   a  and  9   b    show a liner element  50  having an outer annular wall  60 , an inner annular wall  62  complementarily positioned in the outer annular wall  60  and an innermost cylinder  64  complementarily positioned within the inner annular wall  62 . Nano tape  39  is positioned between the outer annular wall  60 , the inner annular wall  62  and the innermost cylinder  64 .  FIGS.  10   a  and  10   b    show a liner element  50  having a square outer annular wall  66 , a square inner annular wall  68  complementarily positioned in the square outer annular wall  66  and an innermost generally square in cross section cylinder  70  complementarily positioned within the square inner annular wall  68 . Nano tape  39  is positioned between the square outer annular wall  66 , the square inner annular wall  68  and the innermost generally square in cross section cylinder  70 .  FIGS.  11   a  and  11   b    show a liner element  50  having octagonal outer annular wall  72 , an octagonal inner annular wall  74  complementarily positioned in the octagonal outer annular wall  72  and an innermost generally octagonal in cross section cylinder  76  complementarily positioned within the octagonal inner annular wall  74 . Nano tape  39  is positioned between the octagon all outer annular wall  72 , the octagon oh inner annular wall  74  and the innermost generally octagonal in cross section cylinder  76 .  FIGS.  12   a  and  12   b    show a liner element  50  having a hexagonal outer annular wall  78 , a hexagonal inner annular wall  80  complementarily positioned in the hexagonal outer annular wall  78  and an innermost generally hexagonal in cross section cylinder  82  complementarily positioned within the hexagonal inner annular wall  80 . Nano tape  39  is positioned between the hexagonal outer annular wall  78 , the hexagonal inner annular wall  80 , and the innermost generally hexagonal in cross section cylinder  82 .  FIGS.  13   a  and  13   b    show a liner element  50  having square outer annular wall  84 , a square inner annular wall  86  complementarily positioned in the square outer annular wall  84  and an innermost generally circular in cross section cylinder  88  complementarily positioned within the square inner annular wall  86 . Nano tape  39  is positioned between the square outer annular wall  84 , the square inner annular wall  86  and the innermost generally circular in cross section cylinder  88 .  FIGS.  14   a  and  14   b    show a liner element  50  having octagonal outer annular wall  90 , an octagonal inner annular wall  92  complementarily positioned in the octagonal outer annular wall  90  and an innermost generally circular in cross section cylinder  94  complementarily positioned within the octagonal inner annular wall  92 . Nano tape  39  is positioned between the octagon all outer annular wall  90 , the octagon oh inner annular wall  92  and the innermost generally circular in cross section cylinder  94 .  FIGS.  15   a  and  15   b    show a liner element  50  having a hexagonal outer annular wall  96 , a hexagonal inner annular wall  98  complementarily positioned in the hexagonal outer annular wall  96  and an innermost generally circular in cross section cylinder  100  complementarily positioned within the hexagonal inner annular wall  98 . Nano tape  39  is positioned between the hexagonal outer annular wall  96 , the hexagonal inner annular wall  98  and the innermost generally circular in cross section cylinder  100 . 
       FIGS.  7   a  and  7   b    show a specific case of the general class of a radially partitioned second liner element  50  into side-by-side segments.  FIGS.  8   a  and  8   b    through  FIGS.  15   a  and  15   b    show specific cases of the general class of radially partitioned second liner elements  50  into nesting and nested segments. Note that some segments can be both nesting and nested. Also note  FIG.  3    shows an example of a nesting and nested segmented element, although not a second liner element  50  but a subliner element of the first type  16 . 
     In general, the segment boundaries of the liner elements  50  (all formable by a “cookie cutter type slicer”) would be oriented in a substantially radial direction (from the standpoint of the wearer&#39;s head  12 , or the outer shell  46 , etc.) but most can never be oriented exactly in the radial direction, in part due to the extended width dimensions of a liner elements  50 . Nevertheless, for simplification purposes, this specification will still be referred to them as “radial.” During an impact that results in a shearing motion of the liner elements  50 , at least some of the adjacent segment surfaces may move relative to each other along their boundaries where the nano tape  39  is located in the radial direction to form S curves (not shown), and through dynamic friction to thereby provide some additional energy absorption. The use of the nano tape  39  increases the dynamic friction between adjacent moving segments resulting in greater energy absorption. The concept of absorbing energy through adjacent surfaces moving relative to each other to form S curves is fully described in U.S. Pat. No. 9,032,558 but without nano tape, which is hereby incorporated by reference in its entirety. The addition of nano tape results in greater energy absorption and is thus an improvement. 
       FIG.  16    illustrates a left side elevational view showing the outer shell  46  of  FIG.  6    positioned on a wearer&#39;s head  12 . The size and shape of the outer shell  46  might be typical of a football helmet. 
       FIG.  17    is a left side elevational view of a wearer&#39;s head  12  showing a face guard  102  attached to the outer shell  46  of  FIG.  8   , and a chin strap  104  positioned on the wearer&#39;s chin and attached to the inner shell  24  of  FIG.  5   , both typical of a football helmet application. 
     Finally, although only a first preferred embodiment having a subliner system  10 , and a second preferred embodiment having a subliner system  10  and an outer shell system  48  have been described in significant detail, the addition of a third liner and a third shell (not shown) would still be within the scope of the present disclosure. It will also be appreciated by those skilled in the art that changes, or modifications could be made to the above described embodiments without departing from the broad inventive concepts of the disclosure. Therefore, it should be appreciated that the present disclosure is not limited to the particular use or particular embodiments disclosed but is intended to cover all uses and all embodiments within the scope or spirit of the described disclosure.