Abstract:
A method of mitigating an incoming pressure wave comprising creating through-holes or channels in a soft foam layer, creating through-holes or channels in a hard foam layer, placing the hard foam layer inside a helmet shell, and placing the soft foam layer on the hard foam layer.

Description:
[0001]    This application claims priority to and benefit of U.S. Patent Application No. 61/524,404 filed Aug. 17, 2011, and U.S. patent application Ser. No. 13/526,003 filed on Jun. 18, 2012, the entireties of both are herein incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    This disclosure provides for mitigating the propagation of pressure into the head from nonpenetrating blasts and provides support between the head and helmet of a soldier. 
         [0003]    The current devices use a foam pad that provides support between the head and helmet of a soldier. The current foam pad is comprised of a hard foam layer and a soft foam layer. 
         [0004]    Previous devices provide less mitigation of pressure into the head compared to the current invention with holes or channels placed in the foam pads. Holes or channels placed at the interface between hard foam and soft foam also mitigate the pressure over previous devices. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    This disclosure provides for mesostructure based scatterers in helmet suspension pads. The foam pad is comprised of a hard foam layer and a soft foam layer. Cylindrical through-holes or channels located in the foam pad are designed to scatter the incoming pressure wave. The through-holes or channels can be placed at the interface to provide an additional mechanism for pressure wave scatter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  illustrates a side view of a helmet with the foam pad invention. The foam pad contains one row of cylindrical through-holes or channels located between the hard foam pad and the soft foam pad. 
           [0007]      FIG. 2  illustrates several views. (a) illustrates a row of holes or channels at the interface of the hard and soft foam layers. (b) illustrates two rows of holes or channels: a first row in the soft foam layer and a second row in the hard foam layer. (c) illustrates three rows of holes or channels: a first row in the soft foam layer, a second row in the hard foam layer, and a third row at the interface of the hard and soft foam layers. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    The method disclosed provides for mesostructure based scatterers in helmet suspension pads. The invention concerns a helmet suspension foam pad designed to reduce the incoming pressure wave caused by non-penetrating blasts to the head. 
         [0009]    The foam pad is comprised of a hard foam layer and a soft foam layer. Cylindrical through-holes or channels located in the foam pad are designed to scatter the incoming pressure wave. The through-holes or channels can be placed at the interface to provide an additional mechanism for pressure wave scatter. The invention can be attached to the helmet and placed onto the head and its orientation relative to the helmet and head can be as follows: the helmet shell, the hard foam layer, the soft foam layer and the head. 
         [0010]    The abovementioned suspension pad design demonstrates the through-hole or channel scatterer design. Other suspension and helmet shell materials may be substituted. The through-holes or channels may also be placed at or away from a material interface. 
         [0011]    The technique of low pass filtering and high pass filtering at different locations in the brain was used to characterize the performance between designs. The technique of taking the absolute integration of the pressure in time at different locations in the brain was also used to characterize the performance between designs. 
         [0012]    The abovementioned suspension pad design demonstrates the through-hole or channel scatterer design. The placement of the holes, the number of holes, and the size of the holes in the foam pad can vary. 
         [0013]    The through-holes or channels may also be placed at or away from a material interface. Different suspension materials may be used. Different helmet shell materials and designs may also be used with the invention. 
         [0014]    This design adds functionality to the foam by introducing an impedance mismatch to the propagation of non-penetrating pressure waves that could come from a nearby blast. This design adds a multifunctional component to the protection provided by the helmet. 
         [0015]    This disclosure vastly improves the existing suspension system by incorporating scatterers into the foam pads of specific hole or channel diameters and distributions to perform several functions. This disclosure teaches how to mitigate pressure infiltration into the brain, pressure which may lead to traumatic brain injuries (TBI). Furthermore, this approach continues to provide support for the helmet shell on the head. 
         [0016]    The approach described herein is a simple design which adds no weight to burden the warfighter and furthermore is a cost effective solution to problems with the helmets currently in use. 
         [0017]    This technology can be used in helmets in a variety of fields—motorcycle helmets, bicycle helmets, and fighter pilot helmets. The current foam pads only provide support between the helmet and the head. This disclosure teaches a simple method and structure to use the suspension pads in order to mitigate pressure into the brain from blunt trauma impacts or other pressure waves. 
         [0018]    This scatterer pad design concept provides improved performance compared to standard designs. Low frequency pressure response is reduced by 36%. High frequency pressure response is reduced by 94%. 
       Example 1 
       [0019]    Using a typical helmet with a hard and soft foam, wherein the hard foam is placed between the soft foam and the helmet shell, holes or channels were cut in the hard and soft foam at the interface between the hard and soft foam components. This system consisted of one row of holes wherein the hole or channel diameter was 6.35 mm. 
       Example 2 
       [0020]    Using a typical helmet with a hard and soft foam, wherein the hard foam is placed between the soft foam and the helmet shell, holes or channels were cut in each of the hard foam and soft foam layers. This system comprised one row of holes or channels in the hard foam and one row of holes or channels in the soft foam in a manner wherein the holes or channels in the hard foam were parallel or nearly parallel to the plane of the length of the hard foam and one row of holes or channels in the soft foam in a manner wherein the holes or channels were parallel or nearly parallel to the plane of the length of the soft foam. The center to center distance in each row was 12.7 mm. The hole or channel diameter was 2.35 mm. 
       Example 3 
       [0021]    Using a typical helmet with a hard and soft foam, wherein the hard foam is placed between the soft foam and the helmet shell, holes or channels were cut in each of the hard foam and soft foam layers. This system comprised one row of holes or channels in the hard foam and one row of holes or channels in the soft foam in a manner wherein the holes or channels in the hard foam were parallel or nearly parallel to the plane of the length of the hard foam and one row of holes or channels in the soft foam in a manner wherein the holes or channels were parallel or nearly parallel to the plane of the length of the soft foam. The center to center distance in each row was 12.7 mm. Additionally, a row of holes or channels were cut in the hard and soft foam at the interface between the hard and soft foam components. The hole or channel diameter was 1.86 mm. 
         [0022]    Many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that the claimed invention may be practiced otherwise than as specifically described. Any reference to claim elements in the singular, e.g., using the articles “a,” “an,” “the,” or “said” is not construed as limiting the element to the singular.