基于数值计算的切割焊接连续加工残余应力演变过程

Residual stresses evolutions of cutting and welding sequential process based on numerical simulation

热切割与焊接在船舶制造中以先后顺序连续作用于构件,形成复杂的工艺耦合残余应力场,给掌握船体结构残余应力分布带来困难。为此,以典型的平板结构切割成形后对接焊工艺过程为对象,基于热弹塑性有限元法,建立该过程的数值计算模型,分析切、焊耦合残余应力的分布规律与演变过程。结果表明,在切焊连续加工中,沿焊缝边缘存在超过材料屈服点的拉应力区,其宽度大于单独进行切割或焊接工艺时的情况;距焊缝较远位置的应力不仅受其温度升降影响,还要平衡热源周围的压应力,因此率先呈现出渐增的拉应力;初始切割残余应力对最终耦合残余应力的影响取决于温度变化梯度的大小。

Thermal cutting and welding usually act on components orderly in shipbuilding,and the coupled residual stresses with complex distribution was induced during this process,which led to difficulty in analyzing the residual stresses distribution.To tackle this problem,the numerical calculation model for the typical process that butt welding between two plates cut by oxygen flame was studied based on thermal elastic-plastic finite element method.The distribution and evolution of coupled residual stresses were analyzed.The results demonstrated that there was a region that the tensile stress values exceeded the yield point of material along the weld seam,and the width of this region was higher than those of cutting and welding execution respectively.The stresses with longer distance away from the weld seam were not only influenced by the temperature itself,but also the compressive stresses induced by welding heat source,so it appeared as the increasing tensile stresses,and the influence of initial cutting residual stresses on the final coupled residual stresses depended on the gradient magnitude of temperature.