Constitutive model for high strain rate response of polymeric composites

A constitutive model for characterizing high strain rate response of polymeric composites was developed using off-axis composite specimens. The difference in the results of coupon and block specimens was experimentally demonstrated and discussed. Off axis block specimens were tested in compression at three different strain rates, 10(-4)/s, 10(-2)/s, and 1/s. Based on these experimental data, a viscoplasticity model was established to describe the nonlinear rate dependent behavior. This viscoplasticity model, although developed based on data for strain rates up to 1/s, was verified with data obtained from high strain rate experiments conducted on a Split Hopkinson Pressure Bar (SHPB) using block off-axis specimens. The axial strain rate in the SHPB tests were in the range of 400-700/s. Comparison of model predictions with experimental data indicated that the viscoplasticity model determined using low strain rate tests was valid for high strain rates at least up to 700/s. (C) 2002 Published by Elsevier Science Ltd.