Research On Clinching Teechnology And Optimization Of Structural Parameters Of Steel And Aluminum Heterogeneous Sheets

Due to the high specific strength of the aluminum alloy,good formability,high hardness,and high wear resistance of high-strength steel,the above two materials have become ideal materials in the lightweight design of automobiles.They are widely used in the design and manufacture of automobile body structures.In recent years,the combination of two materials has been used more and more widely,but due to the difference in the physical properties of the two materials,it is difficult for the traditional spot welding technology to form an effective connection.There is no heat input during the clinching process and the process is simple,so it is widely used in the connection of sheets.However,due to differences in mechanical properties and structural process parameters,the connection quality is unstable.Therefore,improving the connection quality by optimizing the structural process parameters has become an effective means.In this paper,6061 aluminum alloy and HC340/590DP high-strength steel were the research objects.First,the performance parameters of the two materials were obtained through the uniaxial tensile test,and the J-C constitutive model was established;then,the numerical simulation of the clinching process was carried out in the ABAQUS software.The verification results show that the numerical simulation had obtained a joint that was consistent with the geometric shape in the experiment,and the force-displacement curve explained the process of forming the locking mechanism of the two sheets well.The numerical simulation results effectiveness was verified.Study the changing law of joint neck thickness t_n and self-locking value t_u under different structural process parameters.The rule was:when the punch radius X1 or the die radius X2 increases,the neck thickness value t_n and the self-locking value t_u change in inverse proportion.When the die depth X3 increases,the neck thickness value t_n,and the self-locking value t_u decrease at the same time,and the self-locking value t_u decreases more.when the groove width X4 and stroke X5 increase,the neck thickness value t_nchanges are not noticeable,and the self-locking value t_u decreases with the increase of the groove width X4 and increases with the increase of the stroke X5.Analyzing the test design plan and select the optimal Latin hypercube test design and then establishing the BP neural network model,response surface model,and Kriging model.Using the evaluation coefficientR~2 to test the fitting accuracy of the three approximate models,they predicted the neck thickness t_n the evaluation coefficients R~2were 0.791,0.876,0.981;the evaluation coefficients of self-locking value t_u prediction R~2were 0.788,0.842,0.943,respectively.The Kriging model had the best fitting accuracy,so this article used the Kriging model for subsequent optimization.Combining the Kriging model of the clinching process of steel and aluminum heterogeneous sheets with the NSGA-?algorithm to obtain the pareto optimal solution sets of the neck thickness value t_n and the self-locking value t_u.Then the optimization results were verified by experiments,the test results show that the maximum tensile and shear strength of the joints have been increased by 9.4%and 26.4%,respectively,verifying the effectiveness of the optimization method proposed in this paper.