Impact compressive failure of GFRP unidirectional composites

Abstract

Compressive impact tests of unidirectional glass fiber reinforced vinyl ester matrix composites (GFRP) were carried out using the split Hopkinson pressure bars. The dynamic stress-strain curves of unidirectional composites of six different fiber volume fractions and pure matrix were obtained at the strain rate of 103 s-1. Impact recovery tests were also performed to study the impact compressive damage evolution in composites. The temperature dependence up to 100°C was examined to study the temperature effect on the compressive strength. Quasi-static compressive tests of the same specimens at the strain rate of 10-3 s-1 were also conducted for comparison. Failed specimens were examined by optical microscopy. Kinking followed by splitting was found to be the main controlling failure mechanism. GFRP exhibited ductile failure for lower fiber volume fractions, but brittle failure for higher fiber volume fractions. As the temperature increased, the failure mode changed from kinking to microbuckling. Experiments showed that the strain rate has a strong effect on the compressive strength. Some theoretical prediction of the compressive strength was also made based on the failure mechanism and test data.