Numerical evaluation of surface welding residual stress behavior under multiaxial mechanical loading and experimental validations
Numerical evaluation of surface welding residual stress behavior under multiaxial mechanical loading and experimental validations
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DOI：
10.1016/j.ijmecsci.2019.105127
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发表时间：
2020-02-15
影响因子：
7.3
通讯作者：
Farajian, Majid
中科院分区：
文献类型：
--
作者：
Hemmesi, Kimiya;Mallet, Pierre;Farajian, Majid
焊接残余应力一直被认为是结构和构件在服役载荷下的完整性的威胁。然而，如果残余应力和载荷应力之和超过材料的屈服强度，则残余应力在热或机械外载荷作用下会部分甚至全部松弛。如果松弛后残余应力的稳定部分仍然很大，则必须注意残余应力（类似于平均应力）可能会改变施加的应力范围。为了对结构完整性进行可靠的评估，必须准确地了解焊接残余应力场的稳定性。为了研究多轴载荷作用下管道焊缝中焊接残余应力的松弛和再分布，采用有限元软件ABAQUS建立了三维有限元模型。通过SYSWELD软件中的焊接模拟初始计算预定义的残余应力场。为了验证数值模拟，一对夫妇的管状样品制成的钢S355 J2 H TIG焊接，然后在不同的施加载荷水平的机械加载。通过X射线衍射（XRD）在焊接状态下和施加机械载荷后测量表面残余应力，以进行进一步比较。实验研究了纯扭和多轴拉扭复合加载条件下的准静态加载-卸载。预测的焊接残余应力松弛与实测结果吻合较好。数值计算结果与实验结果的一致性验证了有限元模型的正确性。验证模型，然后使用数值评估循环扭转载荷下的残余应力的行为与所使用的材料模型的影响。基于结果，对于这样的材料，主要的松弛发生在第一个周期期间，由于单调屈服，但进一步的松弛可能发生在接下来的周期中，由于塑性应变的积累。
Welding residual stresses have been always seen as a threat to the integrity of structures and components during service loadings. However residual stresses could partially or even totally relax under thermal or mechanical external loads if the sum of residual stresses and load stresses exceeds the material yield strength. If the stable portion of residual stresses after relaxation is still significant, care must be taken that residual stresses, similar to mean stresses, could shift the applied stress range. Accordingly, for a reliable structural integrity assessment an accurate insight into the stable residual stress field is essential.A three-dimensional FE model was implemented in software ABAQUS in order to study the relaxation and redistribution of welding residual stresses in a bead on tube weld under multiaxial mechanical loading. The predefined field of residual stress was initially calculated through a welding simulation in software SYSWELD. To verify the numerical simulations, a couple of tubular samples made of steel S355J2H were TIG welded and then mechanically loaded at different applied load levels. The surface residual stresses were measured by means of x-ray diffraction (XRD) in the as-welded condition and also after applying the mechanical loads for further comparisons. Pure torsion and multiaxial tension-torsion loading conditions in the form of quasi-static loadingun-loading were investigated experimentally. The predicted welding residual stress relaxation conforms well the measurement results. The accordance between the numerical and experimental relaxation results confirmed the validity of the FE model. The validated model was then used to evaluate numerically the behavior of residual stresses under cyclic torsion loading with regard to the influence of the used material model. Based on the results, for such a material, the major relaxation occurs during the first cycle due to the monotonic yielding but further relaxation may take place in the upcoming cycles due to the accumulation of plastic strains.