Projectile penetration into rock/elastomer composites.

Composite materials cast from polyurethane resin, rack aggregates and sand
have been examined to determine their resistance to penetration by 7.62mm ball
and armour piercing high velocity projectiles. The effects of using different "
polymer and rock types were investigated, and the resultant composite mixes
were optimised in'terms of cost effectiveness to obtain a protective material
which may be used to clad buildings.
Optimisation was carried out using response surface theory, initially using
a linear response surface; but subsequently a quadratic one. Variables
considered in the mix optimisation were % polymer by weight, % rock aggregate
by weight, rock aggregate particle size, and polymer hardness. Penetration
tests were carried out on the optimised composites to determine the thickness
required for a given confidence level of bullet containment, and to assess
the effect of composite temperature on impact behaviour.
The static uniaxial compressive, bending and creep characteristics of
the best composite were determined to identify any limitations in its use
as cladding units.