Numerical and experimental studies of damage generation in a polymer composite material at high strain rates

Samples of S2-glass/epoxy composites have been subjected to microstructural investigation after testing in compression at quasi-static and high strain rates using the split Hopkinson pressure bar. A numerical model was developed that accurately describes the high strain rate mechanical response of the samples. Moreover, in contrast with earlier phenomenological or constitutive models, the model can also predict a variety of failure modes such as delamination, matrix cracking or fiber crushing. High-speed photography was used to check the model results. Interrupted tests, followed by metallographic examination, have revealed that the sequence of damage events differs between quasi-static and high strain rate regimes. The effect of sample size on measured mechanical properties is noted and is confirmed via numerical modeling.Army Research Office under Contract Number 47335-EG and National Science Foundation under Grant INT-024277