a typical inventive embodiment describes a tubular shape and comprises a rigid outer layer , an elastomeric middle layer and a rigid inner layer . the elastomeric material is a strain - rate - sensitive polymer having a young &# 39 ; s modulus of approximately 700 - 1000 psi at 100 % strain , and strong strain - rate - sensitivity in approximately the 10 3 / second - 10 6 / second range . by the time that the projectile reaches the rigid inner layer , a projectile that impacts the three - layer system is structurally and kinetically diminished in its destructiveness by the rigid outer layer together with the elastomeric middle layer . furthermore , the elastomeric middle layer becomes more rigid during a brief period in which it absorbs energy from the projectile , then again becomes elastic in a manner formative of a membrane covering the rigid inner layer . the elastomeric membrane tempers leakage if rupturing of the rigid inner layer has occurred .