Abstract: In order to study the failure characteristics of dissimilar materials under different damage defects and temperature environment and promote the application of bonding in vehicle engineering, this paper takes carbon fiber reinforced plastics-steel single lap joint as the research object and carries out experimental research on static tensile mechanical properties. In this study, the common damage defects in engineering and the ambient temperature were taken as variables. Firstly, the static tensile test was carried out on the single lap joint without defects at normal temperature to analyze the mechanical properties and failure modes of the joint. Then, five kinds of joints with different crack locations and lengths were tested to study the effects of different adhesive layer defects on the mechanical properties of CFRP-steel bonded joints. Finally, the study was extended to different ambient temperatures. The research results show that the joints without defects at room temperature mainly fail in cohesiveness, and the defects lead to interface failure. The temperature test results show that the ambient temperature not only affects the mechanical properties of adhesive materials, but also affects the properties of the bonding interface between metal and composite substrate. The synergistic effects of various factors lead to changes in structural strength and failure mode. This study provides the design basis and guidance method for the adhesive connection of composite carbon fiber materials and steel in engineering.

Key words: adhesive joint, adhesive layer defect, cohesion failure, interface failure, ambient temperature, composites