Effect of pre-crack length on Mode I fracture toughness of 3-D angle-interlock woven composites from finite element analyses

Abstract

Abstract Fracture toughness is a key factor to design impact behaviors of composite materials. This paper reports the influence of pre-crack length on Mode I fracture toughness of 3-D angle-interlock woven composites. Double cantilever beam specimens with different pre-crack lengths were tested to obtain load-displacement curves and strain energy release rates. A finite element analysis model at microstructure level was established to reveal the fracture damage development and stress distribution in the specimens. We found that the fracture toughness decreases with increase in pre-crack length. The higher pre-crack length resulted in increased stress concentration at crack tip position and the enhanced crack propagation. The higher strength through-thickness yarns are recommended for improving fracture toughness.