Experimental study on dynamic compressive failure of unidirectional CFRP composites

Abstract

Impact compressive tests of the carbon fiber reinforced unidirectional vinyl ester composites were carried out using the split Hopkinson pressure bars. Composites of six different fiber volume fractions were tested. The dynamic stress-strain curves of CFRP were obtained at a strain rate of 103 s-1. Quasi-static compressive tests of the same specimen were conducted for comparison. Failed specimens under impact loading were examined by SEM (scanning electron microscope). The damage evolution under static loading was recorded by video camera. Test results showed that the compressive failure mechanism changed from shear failure in the unidirectional composites of low fiber volume fraction to kinking and splitting of high fiber volume fraction. The shear failure or kinking occurred on a plane, and the direction of the failure plane was found to depend upon the fiber volume fraction. Experiments also showed that the strain rate has strong effect on the compressive strength.