Forming Rules And Performance Control Of Clinching For Aluminum Alloy Sheets

Aluminum alloy sheets is an important lightweight material in auto industry,which has the advantages of small density,high specific strength,strong corrosion resistance,and good recovery performance.But it has difficulty to join aluminum alloy sheets in the assembly process because of its inferior weldability,which constrained aluminum alloy's application.Clinching is an approach of joining sheets that not need any added element but only need the plastic deformation of the sheets.This method not only can solve the problem of joining aluminum sheets but also greatly conform the need of lightweight.However,this technology has not yet applied maturely to the joining of aluminum alloy sheets owing to its lower ductility and the absence of unitized theory and method about clinching process and the property analysis of clinched structure.Therefore,the finite element analysis?FEA?automatic modeling solving program is developed to improve the efficiency of commercial FEA software.Moreover,the aluminum alloy sheet's clinching process and property optimization is investigated based on numerical simulation.The main research work and conclusions are shown as follows:?1?FEA automatic modeling solving program for clinching process is developed.Established the parametric model of clinching and the automatic updating geometric model and FEA Pre-Processing is achieved by programming.Thus,the FEA automatic modeling solving program is developed based on the software of CATIA and FORGE.?2?Forming rules of clinching for aluminum alloy sheets is investigated.Through the failure mode and mechanical characteristic analysis of the joint,the evaluation index of the joint forming quality was established,and the clinching numerical simulation of the 1.4mm thickness aluminum alloy sheet was carried out.The effect regularity of the process parameters on the quality index was obtained.?3?Exploration for optimization technology of clinching forming process.Combined with the FEA automatic modeling solving program established in this paper,through the Latin hypercube experiment design,numerical simulation and MATLAB programming,a clinching process optimization strategy that combined Kriging model and Multi-objective Genetic Algorithm is established,and the Pareto optimal solutions of the forming quality index is obtained.Some optimized results are selected to carry out numerical simulation and experiments that verified the prediction accuracy and optimization effect.One set of₉)andare 0.407mm and 0.427mm.?4?Research on loading capacity of clinched structure and joint layout.The study on the load bearing capacity of the clinched structure is carried out by using the optimized joint in?3?.The results indicated that the axial strength is the key to ensure the connection reliability.The concept of the equivalent connection width is put forward to describe the actual connection ability of the joint,and the calculation method is given by the mechanical analysis.The design method of the number and position of the joint on the sheet is established.The FEA automatic modeling solving program developed in this paper can make the using of the existing FEA software more convenient and intelligent,which can be extended to other forming fields.The research results on the forming laws,optimization strategy and joint layout of the clinching processing can provide guidance for the application of the technology to the aluminum alloy sheets.