Study On The Process And Numerical Simulation Of Electromagnetic Clinching Joint Of AA5052-DC52D

Electromagnetic clinching process is a new combination of two technologies:electromagnetic riveting and clinching.Due to the process' s wide application range,time saving,high efficiency,and excellent overall performance of its joint,it has very broad development and application prospects in the automotive and aerospace industries.In this paper,the process test and finite element simulation for electromagnetic clinching in the aluminum alloy sheet and the high-strength steel sheet were carried out.The forming process,cross-sectional morphology,mechanical properties and service performance under corrosion conditions of the joint were studied.Firstly,a comparative study was carried out between electromagnetic clinching process and conventional pressure clinching process,and the analysis and evaluation of connection performance of joints were completed by experiments.The results showed that the electromagnetic clinching joint had better interlock performance,higher sheet strength and greater shear load.Compared with conventional pressure clinching joint,the interlock value and maximum shear force of electromagnetic clinching joint were 46.6% and 4.6% higher on average.Meanwhile,both shear failure modes were neck fracture,indicating that the neck strength of upper sheet was much lower than the interlock strength.Secondly,the forming process of electromagnetic clinching joint was simulated based on the Simufact.forming software.The plastic deformation,material flow of sheets and the sealing performance of joint in the process were studied.At the same time,it was found that there was a large stress concentration in the neck area of upper sheet and the contact area between lower sheet and groove.These areas were prone to defects and failures during the forming process and the testing of mechanical properties.Finally,the service performance of electromagnetic clinching joint under corrosion conditions was investigated.The effects of corrosion time on surface topography and mechanical properties of joint were systematically analyzed,and the corrosion mechanism of the joint under neutral salt spray was revealed.As a result,it was found that the morphology changes of sheets in the joint area were more and more obvious with the increase of corrosion time.Simultaneously,the mechanical properties of the joint had also suffered a serious decline.Up to 24 days of corrosion,the maximum shear load and maximum pull-off load of the joint decreased by 22.6%and 42%,respectively.In addition,the pull-off failure mode of the joint was transformed from the initial neck fracture to the sheets separation.The main reason was that in the early stage of corrosion,the coating on the steel sheet and the oxide on the aluminum sheet protected the base material to a certain extent.In the later period,with the peeling of the oxide layer and the penetration ability of chloride ions becoming stronger,a large amount of dissolution occurred in the base material under the combined action of gap corrosion and galvanic corrosion.