Analysis of energy release rate of laser-induced cohesive bonding of carbon fiber-reinforced polyetherketoneketone thermoplastic composites

Abstract

In this study, laser joining of carbon fiber/polyetherketoneketone composites with several patterns was inves-tigated to achieve weight reduction without any mechanical fasteners. The laser beam concentrated the energy, and heat conduction in the through-thickness direction of heterogeneous carbon fiber-reinforced thermoplastics caused molecular diffusion at the joining interface. According to the double-beam cantilever test results, the maximum energy release rate (ERR) was 2.01 J/mm2, which was 900 % higher than that of epoxy adhesive joining using laser power densities in the range of 1.05-1.34 W/mm2. A higher ERR was achieved because the optimized laser joining pattern secured repetitive cohesive joining at the interface. Thus, a complicated and step-wise crack opening was observed, which interfered with the propagation.