Passive armor assembly including an armor member made of a brittle material

Abstract

Disclosed is a passive armor assembly for protecting a body disposed behind it from an impact of a long rod penetrator (hereinafter LRP). The armor assembly includes an armor surface that is capable of exerting asymmetric forces on the oncoming LRP and an armor member being disposed behind the armor surface. The armor member is made of a high compression strength, low density, brittle material, and its thickness along the direction of the impact exceeds the length of the LRP. Preferably, the thickness is at least 1.5 the length of the LRP. In a preferred embodiment the armor member is made of a material exhibiting the combination of fracture toughness smaller than 3 MPam 1/2 , density of less than 2 g/cc, and compression strength of from 10 2 to 10 3 MPa.

1 . A passive armor assembly for protecting a body disposed behind said armor assembly from a predicted impact of an expected long rod penetrator (hereinafter LRP) having a length of less than 600 mm against which said passive armor assembly is designed, said armor assembly comprising
 (i) an armor surface that is capable of exerting asymmetric forces on said LRP and   (ii) an armor member made of a high compression strength, low density, brittle material,   said armor member being disposed behind said armor surface and having a thickness along the expected direction of the predicted impact, which thickness exceeds the length of the LRP.   
   
   
       2 . A passive armor assembly according to  claim 1 , wherein said thickness is at least 1.5 times the length of the expected LRP. 
   
   
       3 . A passive armor assembly according to  claim 1 , wherein said armor member is made of a plurality of sub-members of smaller thickness adjacent to each other. 
   
   
       4 . A passive armor assembly according to  claim 3 , wherein said sub-layers are attached to each other by an adhesive. 
   
   
       5 . A passive armor assembly according to  claim 3 , wherein thickness of each of said plurality of sub-members is at least 20 mm. 
   
   
       6 . A passive armor assembly according to  claim 1 , wherein damage velocity in said armor member is lower than the velocity of the LRP inside it. 
   
   
       7 . A passive armor assembly according to  claim 1 , wherein said armor member is made of a material exhibiting the combination of fracture toughness smaller than 3 MPam, density of less than 2 g/cc, and compression strength ranging from 10 2  to 10 3  MPa. 
   
   
       8 . A passive armor assembly according to  claim 1 , wherein said armor member is made of a material exhibiting the combination of less than 5% elongation to fracture, density of less than 2 g/cc, and compression strength ranging from 10 2  to 10 3  MPa. 
   
   
       9 . A passive armor assembly according to  claim 1 , wherein the armor member is made of a material selected from the group consisting of PMMA, polyester, epoxy resin, and polymeric resins with brittleness increasing agents. 
   
   
       10 . A passive armor assembly according to  claim 9 , wherein said armor is made of a polymeric material and said brittleness increasing agent is a ceramic powder. 
   
   
       11 . A passive armor assembly according to  claim 9 , wherein said armor is made of a polymeric material and said brittleness increasing agent is selected from the group consisting of alumina powder, boron carbide powder or granulates, and silica powder. 
   
   
       12 . A passive armor assembly according to  claim 1 , further comprising a backing layer of ductile material posted behind said armor member. 
   
   
       13 . A passive armor assembly according to  claim 1 , wherein said armor surface is inclined with respect to the impact direction of the LRP. 
   
   
       14 . A passive armor assembly according to  claim 1 , wherein said armor surface is integral with said armor member. 
   
   
       15 . A passive armor assembly according to  claim 1 , wherein there is a distance between said armor surface and said armor member, said distance being at least 5 mm. 
   
   
       16 . A passive armor assembly according to  claim 15 , wherein said armor surface is a layer of a ductile material. 
   
   
       17 . A passive armor assembly according to  claim 16 , wherein said layer of ductile material is too thin to have a protective value by itself. 
   
   
       18 . A passive armor assembly according to  claim 14 , wherein said armor surface is the front surface of said armor member. 
   
   
       19 . A passive armor surface according to  claim 1 , wherein said armor assembly further includes a front non-armor member suitable for protecting it from environmental hazards. 
   
   
       20 . A passive armor assembly according to  claim 1 , comprising discrete modules, as to increase the multiple-hit capability thereof. 
   
   
       21 . An armor member for use in a passive armor assembly for protecting a body disposed behind said armor assembly from a predicted impact of an expected long rod penetrator (LRP) having a length of less than 600 mm,
 said armor member being made of a brittle material having high compression strength and low density,   said armor member having a thickness along the direction of the predicted impact which exceeds the length of the expected LRP.   
   
   
       22 . An armor member according to  claim 21 , wherein said material exhibiting the combination of fracture toughness smaller than 3 MPam, density of less than 2 g/cc, and compression strength ranging from 10 2  to 10 3  MPa. 
   
   
       23 . An armor member according to  claim 21 , wherein said material exhibiting the combination of less than 5% elongation to fracture, density of less than 29/cc, and compression strength ranging from 10 2  to 10 3  MPa. 
   
   
       24 - 28 . (canceled) 
   
   
       29 . The passive armor assembly of  claim 1  wherein the LRP against which said passive armor assembly is designed has a length between 100 and 600 mm. 
   
   
       30 . A passive armor assembly according to  claim 1 , wherein said LRP has a length to diameter ratio of from about 5 to about 35. 
   
   
       31 . A passive armor assembly according to  claim 13 , wherein an angle of inclination of said armor surface is calculated with respect to the horizon. 
   
   
       32 . A passive armor assembly according to  claim 31 , wherein said angle is between 5° and 60°. 
   
   
       33 . A passive armor assembly according to  claim 31 , wherein said angle is between 10° to 50° 
   
   
       34 . A passive armor assembly according to  claim 31 , wherein said angle is about 30°.