Simulation Analysis Of Laser Hybrid Welding Of Rail Car Body Structure

Laser-MIG hybrid welding technology has been widely used in aluminum alloy car body for its excellent performance.At present,there are some limitations in the experimental research on the structural properties of aluminum alloy car body by laser-MIG hybrid welding.Therefore,it is necessary to carry out the performance simulation research of laser-MIG hybrid welding structure with the help of CAE analysis platform,this paper takes laser-MIG hybrid welding structure of aluminum alloy car body as the main research object,and explores numerical simulation of its performance.Research contents include:First of all,the finite element model of laser-MIG hybrid welded joint was established and its residual stress is analyzed.And considering the residual stress,nominal stress method and equivalent structural stress method were used to predict the fatigue life of laser-MIG hybrid welded joints with residual stress,The influence of residual stress on fatigue life of laser-MIG hybrid welded joints under two evaluation methods was investigated.Next,in the background of car body simulation modeling,explores the simplified model of car body laser-MIG hybrid welding structure.Based on HYPERMESH software,different weld modeling methods are used to simulate laser-MIG weld of car body.A more suitable simplified modeling method was explored from the three aspects of accuracy of simplified model,modeling efficiency and reference location selection of fatigue evaluation method.Thirdly,the finite element model of aluminum alloy car body was established and six conditions of static strength were determined according to EN12663-2010 standard to evaluate the static strength of car body,the sub-model of laser-MIG hybrid welding side wall was extracted from the car body with qualified static strength assessment.Finally,the fatigue life prediction of the laser-MIG hybrid welding side wall sub-model was carried out under fatigue condition.Based on the equivalent structural stress method,the fatigue life prediction of the welding seam of the laser-MIG hybrid welding side wall sub-model was carried out,and based on the nominal stress method,the fatigue life prediction of base metal part of laser-MIG hybrid welding side wall sub-model was carried out.The prediction results show that the fatigue life of the side wall of car body is more than 10~7 times,which meets the design requirements of car body.The research in this paper provides a theoretical basis for evaluating the fatigue life of car body laser-MIG hybrid welded structures using equivalent structural stress method.The proposed simplified modeling method for laser-MIG hybrid welding structures can predict the fatigue life of weld joints efficiently and accurately,and it provides practical reference value for finite element modeling of car body laser-MIG hybrid welding structure.