PRESSURE-SENSITIVITY AND CONSTITUTIVE MODELING OF AN ELASTOMER AT HIGH STRAIN RATES

Abstract

Pressure‐shear plate impact experiments have been conducted to study the pressure dependence of the shearing resistance of an elastomer (polyurea) at very high strain rates: 105–106 s−1. Two impact configurations were used. In the first, an unloading longitudinal wave reflected from the rear surface of the target assembly arrives at the sample midway through its loading by the incident shear wave. In the second, an unloading wave reflected from the free rear surface of the flyer arrives at the sample prior to the arrival of the incident shear wave. As a result, the sample is sheared at high strain rates—at both high and low pressure—during a single experiment (first case) or at high strain rates and low pressures (second case). Based on the experimental results, a constitutive model has been developed that involves a hyperelastic spring acting in parallel with an elastic spring and viscoplastic dashpot acting in series. The viscoplastic dashpot is modeled by means of a thermal activation model in which th...