Effect of surface energy on the shear strength of cfrp/steel adhesive joints

Abstract Carbon Fiber Reinforced Plastic (CFRP) and metal adhesive joints have the advantages of lightweight structure, simple process, and no disruption of fiber continuity. The strength of adhesive joints has been the weak point of this structure. In order to provide a reference for the safe design of CFRP adhesive joints, the effect of the different surface energy of metal surfaces on the shear strength of CFRP/steel adhesive joints was studied. The surface energy of the metal surface was changed by changing the roughness of the metal surface. Test pieces with different roughness were designed. Roughness measurement tests, contact angle and surface energy measurement tests, and shear strength tests were conducted. It reveals the evolution of surface energy on the shear strength of CFRP/steel joints. The results show that the surface roughening changes the solid–liquid contact angle, enhances the solid surface energy, increases the wettability and adhesive capacity of the adhesive, and ultimately improves the shear strength. Therefore, improving the surface energy of stainless steel surfaces can significantly improve the shear strength of CFRP/stainless steel adhesive joints.