Characterization and Modeling of Urethane Foams in Ballistic Impact Computations

Urethane and polyurethane foams can be manufactured with a wide range of densities. Different foams with different densities will exhibit significantly different responses when subjected to dynamic events such as ballistic impact. To successfully simulate these materials in numerical hydrocodes, a methodology is required to determine both the deviatoric (strength) and volumetric (equation of state) response of the materials. To this end, cylinders were machined from foams with a wide range of densities. These foams were subjected to both unconfined and confined compression tests, and the data from these tests were used to fit both strength models and equations of state for each of the foam materials. Next, ballistic impact tests were performed where 0.30-cal. projectiles were fired into various foam materials. Numerical simulations of these tests were performed, and the results demonstrate that the material models obtained from the compression tests successfully reproduce the dynamic response of the foams during ballistic impact.