The mixed-mode fracture behavior of epoxy by the compact tension shear test

In this study, pure mode I, pure mode II and mixed mode fracture behavior of an epoxy were investigated. Specifically, the mixed mode values of fracture toughness and critical strain energy release rate (CSERR) were measured. Specimens were subjected to mixed mode loading using compact tension shear (CTS) test. Some experimental modifications were found to be necessary to eliminate rotation and ensure crack propagation at the notch when testing epoxy specimens at high mode II loading. A failure criterion for the mixed mode loading of polymer is developed and its predictions are compared with the experimental results. The crack propagation direction in epoxy was investigated in this research as well. A detailed study of failure mechanisms on the fracture surface was performed. The results indicate that the increase in the value of toughness can be directly related to the fracture morphology.