Research On Mechanical Performance Analysis And Structural Optimization Of Riveted Top Plate Of High-speed Railway

This paper takes the self-piercing riveting joint of the top plate of the high-speed train as the research object,combining elastoplastic deformation theory and display dynamics theory to carry out force analysis and finite element analysis of the riveting process,propose a scheme of joint optimization of multiple key parameters of rivets and molds,It improves the quality of riveted joints and provides guidance for the selection of rivets and molds for riveting body panels,which has important research significance and practical application value.In order to explore the influence of different riveting parameters on the performance of the joint,2mm thick 5083 aluminum alloy plate and 6mm long Mn B4 rivets were selected as the research objects.Through the finite element simulation and sensitivity analysis of the self-piercing riveting process,explore the influence of changing the mold radius,rivet length and mold depth on the quality of the joint forming.The optimal riveting parameters are mold radius 4.40 mm,rivet length6.50 mm,and mold depth 2.00 mm.The main research content and results of the thesis are as follows:1.Based on the basic theory of metal plastic forming.According to the rivet deformation,the riveting process is divided into stages and the force is analyzed,and the common deformation of the riveting is briefly analyzed,and specific reference standards are proposed for the evaluation of the later riveting quality.According to the pressure riveting deformation process,the analytical method is used to give the mathematical expressions of the pressure riveting force of the rivet,the stress of the riveting plate and the expansion of the orifice plate.2.Established the dynamic analysis model of riveting display.The quarter riveting model is obtained by simplifying the riveting process,According to the principle of metal plastic deformation,the formula for the maximum load in the riveting process is obtained,ANSYS finite element simulation analysis software simulates the riveting process,and studies the influence of mold radius,rivet length and mold depth on its forming quality,get the best parameters of mold radius,rivet length and mold depth under a single variable.The appropriate riveting structure parameter interval is selected through the central composite test,so as to establish a quadratic polynomial response surface model reflecting the riveting structure parameters,the remaining thickness and the inner lock length.3.Multi-objective optimization and experimental verification.Import the ternary quadratic parameter equation between the independent variable and the dependent variable into the Isight software,and use the NSGA-Ⅱ algorithm to obtain the Pareto optimized solution between the various parameters.The Pareto optimization solution provides a number of feasible solutions to find the best solution that meets the reality as reasonable as possible,and process the tensile test pieces with the optimized riveting parameters,and verify the mechanical properties of the riveted pieces through tensile experiments.The results show that after optimization,the remaining thickness increased from 0.94 mm to 1.17 mm,an increase of 24.7%;the length of the inner lock increased from 0.76 mm to 0.87 mm,an increase of 14.5%;and the tensile shear force increased from 6.26 k N to 7.98 k N,an increase of 27%.This paper selects multiple rivets and key mold parameters that affect the quality of self-piercing riveted joints.Analyze the relationship between it and the quality index of the joint after forming,and put forward a multi-objective optimization plan to improve the quality of self-piercing riveting joints.It achieves the purpose of improving the connection quality of the car body,reducing the production cost,and promoting the lightweight process of the car body.