Polymers and polymer composites mixed mode fracture testing

In this paper, mixed mode fracture of neat polymer and composite materials was inspected. The neat polymer in the study is made of pure epoxy and the composite consists of long glass fibres embedded in epoxy. The composite in the study differ from layered unidirectional to random fibre composite. To perform the experiment Compact Tension Shear (CTS) testing fixture and three point bending specimens are employed. The experiment is utilized to study the crack behavior in these materials and measure the fracture toughness and calculate the corresponding Critical Strain Energy Release Rate (CSERR). Studying crack propagation through the thickness of the composite and polymer showed that energy released during fracture at different modes of loading is connected to the morphology of the fracture surface.