Optimization of microstructural morphology via laser processing to enhance the bond strength of Al-CFRP

Generating surface-functional microstructures is an effective way to enhance the bonding strength of metal and carbon fiber-reinforced polymer (CFRP). In this study, different microstructural morphologies consisting of two different patterns were generated on the aluminum alloy (A7075) surface via laser processing. The experimental results indicated that different microstructural morphologies contribute to the enhancement of the shear strength of lap joints. The maximum shear strength of these joints was almost four times stronger than that of lap joints without the microstructures. In addition, the investigation indicated that the shear strength was not only determined by surface roughness and contact area but also by the arrangement of different microstructures. These results are mainly due to the combination of mechanical interlocking and physical adhesion. Finally, the corresponding mechanical models of Al-CFRP lap joints were proposed according to the bonding mechanisms and fracture behaviors.