Simulation Analysis Of Welding Residual Stress And Deformation Of Bogie Side Beam

In the process of welding,there is a large local heat input and subsequent rapid cooling.The residual stress and deformation caused by plastic strain will appear near the weld,and the residual stress and deformation will affect the welding fatigue strength and assembly accuracy.At present,the research methods of welding stress and deformation mainly include analytical method,experimental method and numerical method.Numerical method has become the main research method because of its applicability and high efficiency.Based on the numerical method,this thesis studies and summarizes the influence of cold source parameters on the effect of welding with trailing cooling.The calculation accuracy and time of segmented moving double ellipsoid heat source model and welding moving segmented heat source model were compared,and the influence of welding direction and welding sequence on residual stress and deformation of bogie side beam was studied.The influence of cooling distance,cooling strength and cooling range on the effect of welding with trailing cooling is studied by numerical method.The results show that welding with trailing cooling can significantly reduce the welding residual stress and deformation.The longitudinal stress decreases with the decrease of cooling distance.When the cooling distance is 24 mm,the deformation decreases obviously.When the cooling distance is 48 mm and 72 mm,the residual deformation cannot be reduced.The longitudinal stress and deformation decrease with the increase of cooling strength.The longitudinal stress decreases with the increase of cold source length,but the effect of different cold source length on deformation is almost the same.The efficiency and accuracy of two kinds of segmented heat source models are compared.The results show that both of them can improve the calculation efficiency with certain accuracy.The number of segments has little influence on the prediction of residual stress.When the number of segments is 1,the stress prediction has high accuracy.When the number of segments is not 1,the stress fluctuation will appear at the joint of segments.The number of segments has great influence on the prediction accuracy of residual deformation,and the prediction accuracy of deformation will increase with the increase of the number of segments.In the calculation accuracy and efficiency,the segmented moving double ellipsoid heat source model is higher than the welding moving segmented heat source model.Finally,the segmented moving double ellipsoid heat source model is applied to the welding simulation of the bogie side beam to explore the influence of different welding sequence and welding direction on the residual stress and deformation of the bogie side beam.According to the welding simulation analysis of bogie side beam,transverse deformation is the main form of side beam deformation,followed by vertical deformation,and the longitudinal deformation has the least influence on the overall deformation.The analysis of three welding sequence schemes of bogie side beam shows that scheme 2(weld two diagonal welds initially)under different welding sequence can reduce the residual stress and deformation to the greatest extent,and scheme 2 reduces the maximum equivalent residual deformation by 62% compared with scheme 3(weld two vertical plates initially).The analysis of three welding direction schemes of bogie side beam shows that scheme 3(weld from both ends to the middle)under different welding direction can reduce the residual stress to the greatest extent,and Scheme 2(weld from middle to both ends)can reduce the residual deformation to the maximum,scheme 2 reduces the maximum equivalent residual deformation by 56.7% compared with scheme 1(weld from left to right).Therefore,the welding sequence and welding direction should be carefully designed when designing the welding process of bogie side beam.