Strain and stress concentration of ductile composites in full-range deformation by digital image correlation

This study investigates the variation in open-hole strain/stress concentrations within the full deformation range of a ductile self-reinforced poly (ethylene terephthalate) (srPET) composite using the digital image correlation (DIC). Subsequently, DIC was applied to brittle open-hole polymethyl methacrylate (PMMA) for comparison. This demonstrated the influence of the ductility of srPET. The strain concentration factor (Kɛ) of PMMA was constant with a full deformation range and agreed with theoretical concentration factor (Kt). By contrast, the Kɛ of srPETs was divided into five stages based on the propagation of yield extent (beginning from the hole edge) of the specimen, starting from Kt and then increasing to the peak, followed by the lowest value.