Influence of high pulse fluence infrared laser surface pretreatment parameters on the mechanical properties of CFRP/aluminium alloy adhesive joints

Abstract

ABSTRACT Laser surface pretreatment is an effective approach for improving the mechanical properties of adhesive joints. In the case of laser surface treatment of carbon fibre reinforced polymer (CFRP), ultraviolet (UV) lasers and lower pulse fluence infrared (IR) lasers are usually used to ensure the surface pretreatment quality. With respect to improving the surface treatment efficiency as much as possible, the influence of higher pulse fluence (12.7 J/cm2) IR laser pretreatment parameters on the mechanical properties of CFRP/aluminium alloy hybrid joints were investigated in this study. Scanning electron microscopy (SEM), contact angle measurements, confocal laser scanning microscope (CLSM), and X-ray photoelectron spectroscopy (XPS) were used to analyse the surface modification and failure modes of the adhesive surface. Additionally, the influence of the IR laser pretreatment parameters on the failure mode of CFRP/aluminium alloy adhesive joints under tension loading was discussed. The results showed that in addition to surface free energy, subsurface damage and mechanical interlocking were important factors affecting the shear strength of CFRP/aluminium alloy adhesive joints when a higher pulse fluence IR laser was applied for surface pretreatment. Finally, the optimized laser surface pretreatment parameters considering both the treatment efficiency and quality were obtained for the CFRP/aluminium alloy adhesive joint.