FSW Simulation Analysis Of Profile Structure Based On Stress Mapping Buckling Analysis

With the overall development of China’s rail transit industry,the welding process and welding quality of rail vehicles have strict standards in the production and manufacturing of vehicles,which is directly related to the safety of rail vehicles and passengers.Friction stir welding(FSW),as a new solid phase connection technology,is widely used in the production and manufacturing of rail vehicles.There will be welding residual stress and deformation in the process of friction stir welding,which will affect the fatigue life and assembly of welding components.Therefore,it is of great significance to study the residual stress and deformation of FSW components for the engineering application of FSW technology.In this paper,the temperature field,residual stress field and post weld residual deformation of AL6061-T6 aluminum alloy welded members are studied by Thermal elastoplastic method and stress mapping buckling analysis method:(1)Taking the butt welding of AL6061-T6 aluminum alloy plate as the research object,the FSW sequential thermo mechanical coupling finite element model is established,and the moving heat source program of the mixing head is compiled by ABAQUS subroutine dflux to simulate the function of the mixing head.The process of FSW is simulated and analyzed.By comparing the simulation results with the test results,the numerical simulation of FSW is studied on the basis of verifying the rationality and correctness of the numerical simulation scheme.The change of temperature field and stress in welding process is analyzed.The causes of residual deformation are analyzed.The influence of different sizes of welding plate on residual deformation and peak stress before constraint release of welding plate are discussed.(2)Taking the butt welding of AL6061-T6 aluminum alloy plate as the research object,the stress distribution before constraint release is obtained by the thermo elastic-plastic finite element analysis,and it is transformed into the equivalent temperature load applied on the three-dimensional model.Combined with the buckling analysis of the three-dimensional structure,the post welding deformation is predicted based on the stress mapping buckling analysis.The results of the simulation are compared with the results of the THERMOELASTIC-PLASTIC analysis and the test results to verify the feasibility and effectiveness of the stress mapping buckling analysis method used to predict the welding deformation of weldments.(3)The finite element model of friction stir welding(FSW)of AL6061-T6 aluminum alloy profile structure is established.The welding deformation of FSW is predicted by the thermo elastic-plastic finite element method and the stress mapping buckling analysis method respectively,and the results are compared and analyzed.In addition,the influence of the rotating speed and welding speed of the mixing head on the post welding deformation of AL6061-T6 aluminum alloy profile is analyzed.(4)Based on the FSW deformation prediction research based on the stress mapping buckling analysis,the FSW welding deformation prediction of AL6061-T6 aluminum alloy subway side wall structure based on the stress mapping buckling analysis is carried out by using the local integral mapping method.After deeply studying the temperature field and the residual state in the process of friction stir welding of aluminum alloy weldment,it provides theoretical guidance for effectively obtaining the temperature of weldment,reducing the residual stress and controlling the welding deformation,which has practical engineering application value.