高速列车框架焊接的双椭圆柱高斯分布热源模型

Numerical simulation on welding process of high-speed train's frame structure based on double elliptical cylinder Gaussian distribution heat source model

根据高速列车车体结构焊接工艺特点,分析并改进常用高斯热源,提出适用于铝合金惰性气体保护焊接(MIG)的双椭圆柱-高斯分布热源模型.该热源模型基于焊接速度移动,形成的熔池表面为双椭圆形状,热流密度沿厚度方向均匀分布,在径向呈高斯-双椭圆分布.基于热源模型的数学表达,以有限元方法实现了热机耦合的焊接过程仿真,与薄板试验结果比较,温度场分布与降低趋势较好地吻合;拉应力峰值出现在熔合线和热影响区,仿真值、试验值分别为88.8,85 MPa.结果表明,该热源模型有效地模拟焊接温度场时域上的变化过程,准确地预测结构变形、残余应力分布规律,应用于高速列车头车框架结构焊接工艺优化及残余应力评估,为高速列车焊接质量控制及焊接工艺参数选择提供理论指导.

According to the metal inert-gas(MIG) welding characteristics of the typical structure of high-speed train,the double elliptical cylinder Gaussian distribution heat source model was proposed,which is suitable for welding of the aluminum alloy sheet.The heat source model based on the shape of weld pool was double elliptical,and the distribution of heat flux was uniform and Gaussian in the thickness and radial,respectively.The welding process was simulated through thermo-mechanical coupling method by finite element method.A comparison between simulation and experimental distribution of the temperature field shows the tendency of evolutionary processes compatibly.The peak value of stress by simulation and experiment are 88.8 MPa and 85 MPa,respectively.The results show that the heat source model can simulate both the temperature and the stress field during the welding process.This method is using to predict welding residual stress and strain for the high-speed train's frame structure and can help to choose appropriate MIG welding parameters of aluminum alloy in the industry.