Numerical Simulation And Process Optimization Of Spot Welding On The Side Wall Of Stainless Steel Vehicle

Resistance spot welding is a common connection mode in the manufacture of subway stainless steel car body,and its numerical simulation and overall welding deformation research has important engineering practical significance.However,the subway car body has a complex structure and a large number of solder joints,so the numerical simulation of spot welding by thermoelastoplastic method is not only difficult to converge but also takes a long time to calculate,so it is urgent to explore a suitable numerical simulation method.In this paper,on the basis of thermal elastoplastic numerical simulation of single point spot welding,the inherent strain value is extracted,and the inherent strain method is used to study the deformation of the side wall of spot welding vehicle,and the numerical simulation of spot welding of large structure is realized.First of all,the fully coupled method was used to analyze the three-dimensional thermal elastoplasticity of spot welding.Through the analysis of the temperature field of spot welding of SUS301 L stainless steel,it is concluded that the nugget size increases with the increase of welding time and welding current,and decreases with the increase of electrode pressure.Compared with the experimental data,the accuracy of the fully coupled spot welding method is verified.Secondly,the sequential coupling method was used to analyze the three-dimensional thermal elastoplasticity of spot welding.By comparing with the nugget,stress and efficiency calculated by the full coupling method,it is concluded that most of the errors of the nugget size of the sequential coupling method are less than ±10%,the stress error is less than ±5%,and the average calculation time is shortened by 57%.It has a significant advantage in calculation efficiency.Therefore,the sequential coupling method can replace the complete coupling method for the numerical simulation of spot welding.Thirdly,the inherent strain method was used to analyze the deformation of the side wall spot welding module structure.On the basis of the verification of the inherent strain method,the results obtained by sequential coupling analysis were applied to the large shell element structure.The deformation characteristics of the curved skin position in the four-point minimum constraint analysis were studied.through the study,it was found that the deformation of the curved skin position increases in the direction of curvature increase.Based on the comparative analysis of the post-weld deformation of three kinds of positioning constraints,it was found that the deformation of three-point minimum constraint and four-point minimum constraint were roughly the same.for the case of considering only the minimum constraint,the two constraint methods could be adopted.The clamping constraint was designed according to the deformation characteristics of the three kinds of positioning constraints.through the analysis,increasing the clamping constraint plays a positive role in improving the deformation of the side wall spot welding module.On the basis of the above analysis,the influence of different process parameters on the deformation of sidewall spot welding module was studied.it was found that with the increase of welding time,electrode pressure and welding current,it has little influence on the deformation distribution of sidewall spot welding module,but the deformation tends to increase.Finally,the deformation analysis of the whole side wall structure of stainless steel spot welding vehicle is carried out by using the inherent strain method.Through the comparative study of the post-welding deformation of different clamping schemes,it was found that the reasonable clamping constraint was beneficial to the improvement of deformation,increasing the average maximum deformation after clamping and reducing 4.154 mm,and applying clamping to the position of the side beam is more beneficial to the improvement of deformation.