Process Control And Parameter Prediction Of Aluminum Alloy Self-piercing Riveting Based On Response Surface Method

In the field of aluminum alloy lightweight body-in-white design and manufacturing,it is an urgent problem to control the process parameters of self-piercing riveting quickly and accurately,and to predict the riveting quality at the same time.This project mainly carries out the simulation analysis of aluminum alloy self-piercing riveting forming process;based on the response surface method to achieve the control of riveting process parameters and the prediction of mechanical properties;establishes the inverse calculation model of maximum riveting force,the main research work and conclusions are as follows.The finite element model of aluminum alloy self-piercing riveting plastic forming process was established,and the variation characteristics of material flow field,joint mechanical internal locking structure and maximum riveting force in the forming process of aluminum alloy self-piercing riveting joint under different influence factors were explored.The result shows that,during the forming process,the material flow of the substrate plate near the rivet inner cavity,rivet toe and rivet cover is the most intense,resulting in the macro large plastic deformation of these parts,and the riveting force increases sharply and reaches the peak value in the final stage of riveting forming.Punch speed,rivet length,rivet cavity height,rivet hardness,plate thickness and material hardness have certain effects on the mechanical internal lock structure of the joint,the radial flow speed of rivet material and the maximum riveting force in the riveting process.Based on the Box-Behnken Design response surface test design method,the self-piercing riveting process of aluminum alloy was studied.Taking the rivet hardness,plate thickness and material hardness as the influencing factors,the failure load of the joint,the energy absorption value,the piercing pressure during riveting,and the punch stroke were used as response values.The experimental study of aluminum alloy self-piercing riveting response surface technology was carried out,and the prediction regression model between the influencing factors and the response value was established.Combined with the finite element simulation results,the response surface regression model was analyzed.The result shows that,the plate thickness has the most significant influence on the failure load,energy absorption value,piercing pressure and punch stroke.Among the interaction,the interaction of the rivet hardness and plate thickness has the most significant effect on the failure load and energy absorption value.The piecing pressure is most significantly affected by the interaction between the hardness of the rivet and the plate thickness,and the stroke of the punch is most significantly affected by the interaction between the hardness of the rivet and the hardness of the material.The validation test results of the regression model show that,the riveting parameters calculated by the riveting parameter regression model are used to connect two groups of plates,and the error of failure load and energy absorption value between the test value and the model prediction value is less than 10%,which verifies the reliability of the response surface regression model in predicting the riveting parameters and mechanical properties of the joint.Taking rivet as the research object,the plastic flow velocity field of rivet was constructed by considering the geometric characteristic parameters of mechanical internal lock,the geometric and mechanical properties parameters of plates and rivets,and the boundary conditions of the contact surface between punch and rivet.Based on the upper limit method,the inverse calculation model of the maximum stamping load in the riveting process was established and verified by experiments.The average error between the maximum riveting force inversion value and the test value is 9.76%,which verifies the reliability of the model.