The effect of thermal damage on mechanical strengths of CFRP cut with different pulse-width lasers

Abstract

Thermal damage induced by laser machining is known as one of the critical factors weakening the strength of CFRP laminates. In this study, different pulse-width lasers at IR wavelength were used to cut a 6 mm diameter hole on CFRP specimens. Then, we evaluated the influence of HAZ width on the tensile, compressive, and flexural strength of CFRP specimens quantitatively. High-speed camera and numerical simulations were applied to analyze the underlying mechanisms about the influence of HAZ on mechanical properties. The results show that HAZ could weaken the mechanical strength of CFRP. For 1 mm CFRP, the degradation of flexural strength is most sensitive to HAZ, followed by compressive strength. The effect of HAZ on weakening tensile strength is relatively slight. The main reason for weakening the mechanical performances is that exposed carbon fiber within the HAZ cannot bear the load. The larger the HAZ is, the faster the CFRP fails.