Effects of Temperature Environment on Mode II Interlaminar Fracture Toughness in Asymmetric CFRP Laminates

Abstract

When delamination occurs in CFRP laminates due to impact, a portion of the laminate structure becomes asymmetric across the delamination in the thickness direction, resulting in a coupling effect of in-plane and out-of-plane deformations. Thus, it is important to evaluate the coupling effects on the interlaminar fracture toughness and fracture mechanism in CFRP laminates. In addition, it is necessary to withstand practical temperature environments. Based on Verchery's approach, the authors intentionally prepared asymmetric laminates with non-zero and zero-coupling components in the classical lamination theory to evaluate the effects of coupling components on the interlaminar fracture toughness in CFRP laminates. In this study, the Mode II interlaminar fracture toughness of CFRP laminates with and without coupling components in the stiffness matrix was measured by the end notched flexure (ENF) test in the temperature range from room temperature to 80°C. The relationship between the temperature and the interlaminar fracture toughness was quantitatively evaluated. Fracture surface observation was also conducted to clarify the fracture mechanism.