重卡结构件激光-GMAW复合焊接变形数值模拟研究

Laser-GMAW Hybrid Welding Weld-Formation Simulation and Distortion Suppression of Semi-truck Welding Structure

利用热弹塑性有限元分析,对材料为Q235钢的重卡结构件激光-GMAW复合焊接的温度场及焊接变形进行数值模拟计算。将平面高斯热源与高斯倒锥体热源结合,建立了适用于激光-GMAW复合焊接的组合热源模型,计算所得的焊缝横截面形状和尺寸与试验吻合较好。对于整个焊接结构的焊接顺序分成多个部分进行规划,包括了两个待焊面的整体先后顺序、局部的焊接起始位置以及焊接路径选择,焊接路径包括顺序焊、分步退焊、跳焊。在结构上选取4条关键路径,并将路径上各点的z方向位移量进行标准差计算,并取平均值,作为整个结构z方向变形程度系数,建立了针对具有复杂变形趋势和变形分布的焊接结构的变形严重程度定量评估方法。将各步骤内的最优方案进行结合,最终得到的最优焊接顺序方案为先焊A面后焊B面,且B面采用跳焊路径,3号位置作为焊接起始位置。最优方案焊接变形程度系数为0.2 mm,与最差焊接方案相比,焊接变形程度系数降低了28.6%。

This paper predicts the temperature field and post-weld deformation of semi-truck structures with Q235-steel fillet welds fabricated by laser-GMAW hybrid welding via thermo-mechanical FEM analysis.A combined volumetric heat source consisting of planar gaussian heat source and conical volumetric heat source.was applied in the thermal analysis.The numerical results showed that the computed cross-sectional shape and weld size coincides well with the experimental ones.This consistency proves the validity of the combined planar and conical gaussian heat source in the temperature-field simulation of laser-GMAW hybrid welding.The welding sequence has been planned step by step,including the overall sequence of double-side structures,the starting position,and the selection of welding paths between sequential welding,backstep welding,and jump welding.Four key paths have been selected and the average value of z-direction displacement of points at each path has been calculated as the deformation coefficient of the entire structure so that a quantitative evaluation method for complicated-structure deformation was established.The optimum method in each step has been combined and the final strategy is to weld A side first and to adopt jump welding path and No.3 starting position when welding B side.The optimized welding deformation coefficient of the post-welding structure is 0.2 mm,which is 28.6%lower than the worst weld‐ing sequence's coefficient of 0.28 mm.