Evaluation of Interfacial Behavior of FRP Composites in DCDC Test. Fracture of Fiber/Matrix Interface in Mixed-Mode.

Abstract

A double cleavage drilled compression (DCDC) specimen with fiber/matrix interface has been proposed and analyzed in mixed-mode using the boundary element method (BEM). At the same time, the experiments on this DCDC specimen were conducted for CFRP composites in order to examine the crack propagating behavior and calculate the interfacial fracture energy at the fiber/matrix interface. It was confirmed that the DCDC specimen with the hole offset from the mid plane has a mixed-mode stress distribution, and the effect of the mode II on interfacial fracture energy increases with the offset value. The DCDC specimen in mode I with bridge fiber at the mid plane is also analyzed. It is found that the transition from the mode I to the mixed-mode occurs when the bridge fiber with angle to the mid plane exists. It was shown that the DCDC test is a useful method for evaluating the interfacial behavior of fiber reinforced plastic materials. However, both experimental and analytical approaches are needed to achicve a quantitative evaluation of the fiber/matrix interface.