Cutting-induced plasticity can lead to elevated uncertainties in residual stress measurements made by the contour method. In this study plasticity-induced stress errors are numerically evaluated for a benchmark edge-welded beam to understand the underlying mechanism. Welding and cutting are sequentially simulated by finite element models which have been validated by previous experimental results. It is found that a cutting direction normal to the symmetry plane of the residual stress distribution can lead to a substantially asymmetrical back-calculated stress distribution, owing to cutting-induced plasticity. In general, the stresses at sample edges are most susceptible to error, particularly when the sample is restrained during cutting. Inadequate clamping (far from the plane of cut) can lead to highly concentrated plastic deformation in local regions, and consequently the back-calculated stresses have exceptionally high values and gradients at these locations. Furthermore, the overall stress distribution is skewed towards the end-of-cut side. Adequate clamping (close to the plane of cut) minimises errors in back-calculated stress which becomes insensitive to the cutting direction. For minimal constraint (i.e. solely preventing rigid body motion), the plastic deformation is relatively smoothly distributed, and an optimal cutting direction (i.e. cutting from the base material towards the weld region in a direction that falls within the residual stress symmetry plane) is identified by evaluating the magnitude of stress errors. These findings suggest that cutting process information is important for the evaluation of potential plasticity-induced errors in contour method results, and that the cutting direction and clamping strategy can be optimised with an understanding of their effects on plasticity and hence the back-calculated stresses.

中文翻译：

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使用轮廓法评估残余应力测量中与切削诱发塑性相关的误差

切削引起的塑性可导致轮廓法测量残余应力的不确定性增加。在这项研究中，对基准边焊梁的塑性引起的应力误差进行了数值评估，以了解潜在的机制。焊接和切割依次通过有限元模型进行模拟，这些模型已通过先前的实验结果进行验证。发现垂直于残余应力分布对称平面的切削方向会导致基本上不对称的反向计算应力分布，这是由于切削引起的塑性。通常，样品边缘处的应力最容易出错，尤其是当样品在切割过程中受到限制时。夹紧不足（远离切割平面）会导致局部区域高度集中的塑性变形，因此反向计算的应力在这些位置具有异常高的值和梯度。此外，整体应力分布向切削末端侧倾斜。充分夹紧（靠近切割平面）可最大限度地减少反向计算应力的误差，该应力对切割方向变得不敏感。对于最小约束（即仅阻止刚体运动），塑性变形分布相对平滑，并确定了最佳切割方向（即从母材向焊缝区域切割，方向落在残余应力对称平面内）通过评估应力误差的大小。