Abstract Most of the existing theoretical studies to predict 3D-crack-front shape change are confined to plate-like structures. In this paper, a transient three-parameter geometric model with fewer constraints located on equivalent deflected crack planes is developed by using space oblique extension circles for a transverse surface crack in a solid round bar under fatigue tension-torsion loading. The results show that the proposed mathematical and numerical analysis method can get more effective prediction with fewer iterations. It is verified by comparing the formation outcome of crack growth obtained by visualization of the predicted crack-front shapes with other numerical solutions and experimental results.

中文翻译：

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疲劳拉扭复合载荷作用下圆柱杆裂纹形状预测

摘要 现有的预测 3D 裂纹前缘形状变化的理论研究大多局限于板状结构。在本文中，针对疲劳拉扭载荷下实心圆棒中的横向表面裂纹，使用空间斜延伸圆建立了位于等效偏转裂纹平面上的约束较少的瞬态三参数几何模型。结果表明，所提出的数学和数值分析方法能够以较少的迭代次数获得更有效的预测。通过将预测的裂纹前沿形状可视化获得的裂纹扩展的形成结果与其他数值解和实验结果进行比较，验证了这一点。