A new numerical method, verified by the analytical solution of the weight functions and experimental paths, is developed to evaluate the crack initiation and propagation generally in mixed mode (I-II). This numerical method combining the interaction integral method and the maximum tangential stress (MTS) criterion is based on the finite element method of secondary development. The influence of combined confining pressure and diametric forces on crack propagation trajectories for CCBD specimens are studied. It is indicated that the crack propagation direction independent of the confining pressure keeps the same with the line of original crack as the loading angle is equal to [Formula: see text]. But when the loading angle is greater than [Formula: see text], the curvature of the curve trajectory in the early stage of crack propagation increases with a larger confining pressure. Further, it is found that larger values of the loading angle and relative length will make the effect of confining pressure more significant at the early stage of crack growth.

中文翻译：

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围压下CCBD试件混合模式(I-II)断裂扩展的数值研究

开发了一种新的数值方法，通过权函数的解析解和实验路径验证，以评估混合模式 (I-II) 下的裂纹萌生和扩展。这种结合相互作用积分法和最大切向应力（MTS）准则的数值方法是基于二次开发的有限元法。研究了组合围压和直径力对CCBD试样裂纹扩展轨迹的影响。表明当加载角等于[公式：见正文]时，与围压无关的裂纹扩展方向与原始裂纹线保持一致。但是当加载角度大于【公式：见正文】时，裂纹扩展早期曲线轨迹的曲率随着围压的增大而增大。此外，研究发现加载角和相对长度的值越大，在裂纹扩展的早期阶段，围压的影响就越显着。