Apparatus and method to measure back face signature of armor

Abstract

An apparatus and method for evaluating the backface signature of flat panel ballistic resistant composites with accuracy, repeatability and improved correlation to the expected backface signature of shaped ballistic resistant composites in actual field use.

1 .- 20 . (canceled) 
     
     
         21 . An apparatus for evaluating the backface signature of a fibrous material, the apparatus comprising:
 a) a deformable backing medium having a front surface;   b) a spacer defining a space adjacent to said deformable backing medium, the spacer spacing a fibrous material that is positioned adjacent to said deformable backing medium apart from the front surface of said deformable backing medium; and   c) optionally, at least one support for supporting a fibrous material in a position adjacent to the front surface of said deformable backing medium.   
     
     
         22 . The apparatus of  claim 21  wherein said deformable backing medium is contained in an open face fixture. 
     
     
         23 . The apparatus of  claim 21  wherein said spacer comprises an element having a border and an interior cavity defined by said border, wherein said deformable backing medium is exposed through said cavity. 
     
     
         24 . The apparatus of  claim 23  wherein said spacer comprises a flat, rigid panel. 
     
     
         25 . The apparatus of  claim 23  wherein said spacer comprises an element having a thickness of at least about ⅛ inch (0.3175 cm) and said interior cavity has a depth that is equal to the thickness of said flat panel. 
     
     
         26 . The apparatus of  claim 21  wherein said spacer defines a space adjacent to said deformable backing medium of at least about ½ inch (1.27 cm). 
     
     
         27 . The apparatus of  claim 21  wherein said deformable backing medium is contained in an open face box-shape fixture, wherein said spacer comprises a flat panel having an interior cavity having a depth of at least about ½ inch (1.27 cm), wherein said deformable backing medium is exposed through said cavity, and wherein said spacer is positioned in direct contact with front surface of the deformable backing medium. 
     
     
         28 . The apparatus of  claim 21  wherein said deformable backing medium is contained in a fixture having both an open front face and an open rear face, wherein said open rear face of the fixture is at least partially covered by a removable cover, wherein said removable cover is optionally secured to said rear face by a reinforcing element. 
     
     
         29 . The apparatus of  claim 21  wherein said optional at least one support is provided and comprises at least one supporting bracket that is attached to or integral with said spacer. 
     
     
         30 . The apparatus of  claim 21  which further comprises a fibrous material positioned adjacent to said deformable backing medium, wherein said spacer is positioned between the fibrous material and said deformable backing medium, and which fibrous material is spaced apart from the front surface of said deformable backing medium by said spacer. 
     
     
         31 . The apparatus of  claim 30  wherein said fibrous material is secured to said spacer by at least one reinforcing element, said at least one reinforcing element also optionally securing said spacer to said deformable backing medium. 
     
     
         32 . The apparatus of  claim 21  wherein said at least one support and said spacer comprise a single element that both supports a fibrous material in a position adjacent to the front surface of said deformable backing medium and also spaces a fibrous material that is positioned adjacent to said deformable backing medium apart from the front surface of said deformable backing medium. 
     
     
         33 . The apparatus of  claim 21  wherein said spacer comprises an element having a border and an interior cavity defined by said border, and wherein said spacer further comprises at least one air venting channel recessed within said border, said at least one channel extending through at least one edge of said border and being provided at an interface of said spacer with an adjacent fibrous material. 
     
     
         34 . The apparatus of  claim 33  wherein said spacer comprises a plurality of air venting channels, each channel extending through both an exterior edge of said border and through an interior edge of said border, wherein said interior edge of said border defines said cavity of said spacer. 
     
     
         35 . An apparatus for evaluating the backface signature of a fibrous material, the apparatus comprising:
 a) a deformable backing medium compliant with NIJ Standard 0101.06, the deformable backing medium having a front surface; said deformable backing medium being contained in an open face fixture;   b) a spacer defining a space adjacent to said deformable backing medium, the spacer spacing a fibrous material that is positioned adjacent to said deformable backing medium apart from the front surface of said deformable backing medium by at least about ⅛ inch (0.3175 cm), said spacer comprising an element having a border and an interior cavity defined by said border, wherein said deformable backing medium is exposed through said cavity, and wherein said spacer is positioned in direct contact with front surface of the deformable backing medium; and   c) at least one support for supporting a fibrous material in a position adjacent to the front surface of said deformable backing medium.   
     
     
         36 . The apparatus of  claim 35  which further comprises a fibrous material positioned adjacent to said deformable backing medium, which fibrous material is supported in a position adjacent to the front surface of said deformable backing medium by at least one support, which fibrous material is spaced apart from the front surface of said deformable backing medium by said spacer. 
     
     
         37 . The apparatus of  claim 35  wherein said spacer comprises an element having a border and an interior cavity defined by said border, and wherein said spacer further comprises at least one air venting channel recessed within said border, said at least one channel extending through at least one edge of said border and being provided at an interface of said spacer with an adjacent fibrous material. 
     
     
         38 . A method for evaluating the backface signature of a fibrous material, the method comprising:
 I) providing an apparatus for evaluating the backface signature of a fibrous material, the apparatus comprising:
 a) a deformable backing medium having a front surface; 
 b) a spacer defining a space adjacent to said deformable backing medium, the spacer spacing a fibrous material that is positioned adjacent to said deformable backing medium apart from the front surface of said deformable backing medium; 
 said spacer comprising an element having a border and an interior cavity defined by said border, wherein said deformable backing medium is exposed through said cavity; and 
 c) optionally, at least one support for supporting a fibrous material in a position adjacent to the front surface of said deformable backing medium; 
   II) positioning a fibrous material adjacent to said deformable backing medium, wherein said spacer is positioned between the fibrous material and said deformable backing medium, the fibrous material being spaced apart from the front surface of said deformable backing medium by said spacer;   III) firing at least one projectile at the fibrous material at a target location that corresponds to the interior cavity of said spacer, and such that the projectile impacts the fibrous material at a location that corresponds to the interior cavity of said spacer, and wherein the impact of the projectile on the fibrous material causes a depression in the deformable backing medium;   and   IV) measuring the depth of the depression in the deformable backing medium.   
     
     
         39 . The method of  claim 38  wherein steps III) and IV) are repeated at least once using a similar projectile and at an equal or similar firing velocity, and calculating an average depth of depression in the deformable backing medium. 
     
     
         40 . The method of  claim 38  wherein the projectiles are fired at the fibrous material according to the conditions of Department of Defense Test Method Standard MIL-STD-662F.