Strain and stress conditions in sheet metal shearing are of interest for calibration of various fracture criteria. Most fracture criteria are governed by effective strain and stress triaxiality. This work is an attempt to extend previous measurements of strain fields in shearing of steel sheets with the stress state calculated from the measured displacement fields. Results are presented in terms of von Mises stress and stress triaxiality fields, and a comparison was made with finite element simulations. Also, an evaluation of the similarities of the stress conditions on the sheet surface and inside the bulk material was presented. Strains and von Mises stresses were similar to the surface and the bulk material, but the stress triaxiality was not comparable. There were large gradients in strain and stress around the curved tool profiles that made the result resolution dependent and comparisons of maximum strain and stress values difficult. The stress state on the sheet surface calculated from displacement field measurements is useful for validation of a three-dimensional finite element model.

中文翻译：

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中高强度钢板剪切过程中裂纹萌生时的应变和应力条件

钣金剪切中的应变和应力条件对于校准各种断裂标准非常重要。大多数断裂标准受有效应变和应力三轴性支配。这项工作是为了扩展先前在钢板剪切中应变场的测量结果，并根据测得的位移场计算出应力状态。结果以von Mises应力和应力三轴性场表示，并与有限元模拟进行了比较。而且，提出了对片材表面和散装材料内部的应力条件的相似性的评估。应变和冯·米塞斯应力与表面和块状材料相似，但三轴应力却不可比。弯曲刀具轮廓周围的应变和应力存在较大的梯度，这使得结果分辨率依赖于最大应变和应力值的比较。通过位移场测量计算得出的板材表面的应力状态对于验证三维有限元模型很有用。