Characterization of Mixed-Mode Energy Release Rates for Carbon Fiber/Epoxy Composites Using Digital Image Correlation

Abstract

There is great interest in using advanced mechanical characterization techniques, such as Digital Image Correlation (DIC), to investigate complex fracture behavior of fiber-reinforced composites. In this study, unidirectional carbon fiber/epoxy composites were fabricated from the pre-preg carbon fiber epoxy tapes for the characterization of their energy release rates. Quasi-static mixed-mode fracture experiments were performed using a Wyoming Test Fixture. The crack tip response of the composite was determined by using the displacement fields obtained from DIC based on LEFM. The fracture parameters obtained from the DIC analysis have been compared to those determined from the global load displacement response using ASTM standard. The results show that the experimental investigation of the energy release rates using more local, near field displacements around the crack tip obtained by DIC provide accurate quantification of the crack tip response relative to the global loading conditions. Effects of global bending and fixture compliance on the global load–displacement response can also be eliminated by using full-field DIC measurements.