High Strain Rate Responses and Failure Analysis in Polymer Matrix Composites – An Experimental and Finite Element Study

Compressive properties and failure analysis of unidirectional and plain weave S2-glass/vinylester composites under high strain rate (HSR) loading have been investigated using the Split Hopkinson Pressure Bar (SHPB) technique. A systematic experimental approach has been adopted in this work to identify the damage progression at various stress levels and the strain rate effects on composites. The classical SHPB apparatus has been incorporated by a wave-trapping mechanism to apply a predetermined level of impact loading and to restrict the repeated loading. This facilitates identification of the microstructural damage progression during the loading period. The stress–strain responses at various strain rates in all three principal directions are investigated and the relevant failure modes are also identified by microscopic examinations. The quasi-static compressive strength, the strain to failure, and the elastic moduli are compared with SHPB test results to determine the shift in the failure mechanism. The compressive strength and failure strain for both unidirectional and plain weave composites are observed to be rate dependent. Such rate dependencies of compressive response are analyzed and correlation between the failure modes and the rate effects on composites are established. Finally, a three-dimensional transient finite element analysis (FEA) has also been carried out for unidirectional composites under high strain rate loading in order to have a thorough understanding of the failure mechanisms. Loads are applied in thickness, fiber and transverse of fiber directions and corresponding stress contours are simulated. The FEA prediction of the stress–strain behavior in all the three principal directions of loading correlates well with the high strain rate experimental results.