Abstract: The mixed mode Ⅰ-Ⅱ crack propagation behaviors when K_Ⅰ=K_Ⅱ were studied based on the geometrical modeling for stress singularity boundary multi-direction cracking, the energy release rate and the energy-based driving force of crack side-branching and kinking had been established, and the critical initiation angle or the critical stress intensity factor had also been calculated. The prediction of critical crack kinking angle by the present theory had a good agreement with 2024-T3, and the deviation was estimated to be 8.9% when compared with En3B and Al.

Key words: Mixed mode Ⅰ-Ⅱ crack, Multiple cracks initiation, Critical crack side-branching angle, Crack kinking angle

摘要： 利用奇异应力边界多裂纹开裂的几何模型，研究了应力强度因子K_Ⅰ和K_Ⅱ等值情况下的Ⅰ-Ⅱ复合型裂纹复杂开裂行为，给出了边翼分叉开裂和折裂对应的能量释放率、能量型开裂驱动力、临界开裂角或临界应力强度因子。通过此方法预计的临界折裂角理论值与已有的文献中2024-T3铝合金试样实验值吻合，与En3B低碳钢和一定条件下的铝试样最大偏差为8.9%。

关键词: Ⅰ-Ⅱ复合型裂纹, 开裂分叉, 临界边翼分叉角, 折裂角