Quantitative analysis of fatigue service failure law of 5182 aluminium alloy clinched joints

This study investigates 5182 aluminum alloy clinched joints during fatigue service. The natural frequency of joints was periodically monitored through alternating dynamic response-strength degradation tests. The residual static strength was measured throughout the fatigue service process. The failure mechanism of fatigue degradation was quantitatively analyzed using natural frequency variations and strength degeneration laws. A quantitative method for joint service failure was established based on a nonlinear residual strength theoretical model and cumulative damage model. The results demonstrate that the natural frequency curve undergoes a significant leftward shift during fatigue loading. As the service life increases, the natural frequency of the joint gradually decreases, and the residual strength of the joint also decreases. The trend of the natural frequency and residual strength with the number of fatigue cycles is roughly the same, and the curve is clearly divided into stages. Both show a decreasing process from gentle to sharp. Based on the two models, a theoretical formula for the fatigue strength degradation of clinched joints was derived. A residual strength prediction model for 5182 aluminum alloy clinched joints was further established, and it shows validated practical effectiveness.