Computational Mechanics of welds and welded structures

弧焊是一种复杂的制造工艺，其中电弧以大约1至10毫米/秒的速度在大约1平方厘米的区域内产生热量，形成体积通常略小于1平方厘米的液态金属池。当熔池后缘的液态金属在几毫秒内凝固时，就形成了焊缝。瞬态温度场驱动了材料的冶金相变和热膨胀，改变了材料的温度相关性能。在加热和冷却过程中，其显微组织相发生变化。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。塑性应变率导致残余应力、变形和损伤。在焊接过程中，会形成裂纹、气孔等各种缺陷。由于裂纹和孔隙可能是应力-应变历史的函数，因此对于设计工程师来说，对每个焊缝附近的瞬态应力和应变场进行可靠的估计以评估开裂的风险是很重要的。焊缝的残余应力对在役失效风险起着重要的作用。

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.