基于FEM的高速列车地板结构焊接顺序优化

借助非线性有限元软件MSC．Marc，模拟了高速列车铝合金挤压型材地板结构在现行工艺条件下的焊接变形．为提高计算精度，采用移动的双椭球热源模型模拟MIG焊接过程，母材6N01和焊丝ER5356两种材料随温度变化的热物理性能参量．结果表明，采用7块铝合金挤压型材拼焊的高速列车地板结构，焊后地板结构在各焊缝位置上沿厚度方向上（Y向）产生正V形的角变形，地板结构纵向中心横截面上最大挠曲变形为14．86mm．在此工作基础上提出由外侧向中心侧对称焊接地板结构的优化方案，焊后变形规律与现行工艺一致，但是横向挠曲变形量仅为现行工艺条件下的78．6％．对于大型复杂构件，可以利用结构自身重力的作用控制焊接变形．

Welding sequence optimization for high-speed rail floor based on FEM

Based on the thermo-mechanical coupling analysis with nonlinear commercial software MSC.Marc,the welding deformation of large-scale hollow extruded aluminum alloy high-speed rail floor was simulated under present technological conditions.A moving double-ellipsoid heat source was employed in the model for MIG welding process,and the dynamic mechanical and thermal-physical properties of the 6N01 aluminum alloy and ER5356 filler metal were adopted to improve the calculation precision.The results show that the as-welded deformation of rail floor joined by seven pieces of aluminum alloy extrusion profiles was V-type angular distortion in the thickness direction,and the maximum deflection was 14.86 mm in the horizontal direction.Moreover,an optimized welding sequence was put forward,which was symmetrically welding from the lateral to the center.With the same deformation tendency,the deflection of the optimized rail floor weld was reduced to 78.6% of that under the present scheme.For large-scale and complex structures,gravity should be seriously considered for control of welding deformation.