Computational Mechanics of welds and welded structures

电弧焊接是一种复杂的制造工艺，其中电弧在以大约1至10 mm/s的速度行进的同时在大约1 cm 2的面积内产生热量，以形成体积通常略小于1 cm 3的液态金属池。当熔池后缘的液态金属在毫秒内凝固时，就形成了焊缝。瞬态温度场驱动冶金相变、热膨胀并改变材料的温度相关性质。在加热和冷却过程中，组织相发生变化。由于结构的热胀冷缩、相变和约束引起的应变产生应力和塑性变形。塑性应变速率导致残余应力、变形和损伤。在焊接过程中，可能会形成各种缺陷，如裂纹和气孔。由于裂纹和气孔可能是应力-应变历史的函数，因此设计工程师必须对每个焊接接头附近的瞬态应力和应变场进行可靠的估计，以评估开裂风险。焊缝中的残余应力在服役失效风险中起着重要的作用。

Arc welding is a complex manufacturing process in which an electric arc generates heat in an area approximately 1 cm2 while travelling at speeds of approximately 1 to 10 mm/s to form a pool of liquid metal with volume usually slightly less than 1 cm3. As the liquid metal on the trailing edge of the weld pool solidifies in milliseconds, a weld is created. The transient temperature field drives metallurgical phase changes, thermal expansion and changes temperature dependent properties of the materials. The microstructure phases change as it is heated and cooled. The strain due to thermal expansion-contraction, phase changes and restraint of the structure generates stress and plastic deformation. The plastic strain rate leads to residual stress, deformation and damage. During the welding process, various defects such cracks and pores can form. Because cracks and pores can be a function of the stress-strain history, it is important for design engineers to have reliable estimates of the transient stress and strain fields in the neighbourhood of each weld joint to assess the risk of cracking. The residual stress in welds plays an important role in the risk of in-service failure due.