Research On The Properties And Fatigue Life Of Clinched Joints On 5182 Aluminum Alloy

In vehicle-lightweight engineering,the combined use of thin sheet materials and new joining techniques has become a key focus and a hot topic of research in the transport sector in recent years.A representative of lightweight materials,5182 aluminum alloy has widely used in automotive body panels,steering wheels,and other components due to its high strength and low density.Clinching is a reliable means of joining thin sheets thanks to its high processing efficiency,good forming results,and the ability to achieve a reliable connection with heterogeneous sheets.During service,clinched joints are prone to fatigue failure and unpredicted fatigue failure is a serious risk factor in engineering practice.At present,not only are there no means of identifying the service condition of aluminum alloy embossed joints,but the fatigue failure mechanism of the joints is not clear.There is no clarification of the cracking pattern and failure process of joints,nor is there a method of service condition identification and life prediction for the whole life cycle of joints.In this thesis,5182 aluminum alloy homogeneous clinched joint and a copper foam sandwich joint are prepared with the help of the characteristics of the foam metal,to compare and analyze the difference in the static mechanical properties of the joint and to investigate the fatigue failure mechanism of the joint.Based on the experimental modal analysis method,a full-lifecycle life prediction model for clinched joints under different load levels is constructed using the natural frequency as a parameter.The specific studies are:(1)The most suitable mold was selected for the reliable connection of the two types of joints.The consistency of the joint forming is ensured by controlling the bottom thickness,and the optimum forming parameters are determined.(2)Fatigue tests were carried out on two sets of joints based on static tests,and the test data were processed using statistical principles.The effect of the foam metal sandwich on the fatigue performance of the joints under different loads was investigated using linear fitting and three-parameter fitting methods.(3)Using experimental modal analysis as a non-destructive testing method,alternating fatigue-dynamic response tests were carried out to investigate the dynamic response characteristics of 5182 aluminum alloy clinched joints under fatigue loading and to analyze the variation law between the intrinsic frequency and the number of cycles of fatigue loading.(4)Based on the dynamic response variation law and combined with the fatigue damage accumulation principle,the full-lifecycle life prediction model of 5182 aluminum alloy embossed joints under different load levels was established and the prediction accuracy of the selected model was verified.