Bond-slip failure characteristics of Fe-SMA-steel adhesively bonded joints

The adhesively bonded method has gained increasing popularity in strengthening steel structures due to its excellent mechanical performance and efficient applicability, while the bond-slip failure characteristics of the Fe-SMA-steel bonded interface have received very limited attention. In light of this background, the bond-slip behavior of Fe-SMA-steel adhesively bonded joints is experimentally explored under shear tests in this study. Forty-five single-lap joints are tested to investigate the effects of adhesive type, adhesive layer thickness, steel plate thickness, and bond length. Test results indicate that the failure modes in Fe-SMA-steel adhesively bonded joints vary according to the adhesive used, resulting in distinct strain distributions. The bond capacity of the joints subjected to adhesive layer failure is higher than that of the joints subjected to interface debonding. Simplified bond-slip consecutive models of bonded interfaces with three types of adhesives are proposed and validated with experimental findings, featuring the predictive formulas of critical parameters including peak shear stress, local slip, and corresponding ultimate slip at the peak shear stress. Also, theoretical models for bond capacity and effective bond length of Fe-SMA-steel interface are proposed by introducing stiffness reduction coefficients into the existing studies on CFRP-steel interface. Compared to experimental outcomes, the revised model can offer satisfactory predictions and practical guidance for the interfacial behavior of Fe-SMA-steel adhesively bonded joints.