中文摘要：

通过对脆性断裂过程中开裂扩展机理的分析，提出了径向平面最大Mises应力（RPMS）概念。在平面应变条件下考虑泊松比的影响，对不同应力复合比的Ⅰ-Ⅱ复合型载荷作用下裂尖处应力分布进行了分析，以此为基础，考虑裂尖处三向应力状态对断裂过程的影响，将径向平面上的最大Mises应力作为裂纹开裂扩展的控制因素。据此，针对复合型载荷模式，提出了裂尖复合脆性断裂判据及裂纹开裂方向表达式。将计算结果与现有试验或其他理论进行了对比分析，以此验证了该径向平面上最大Mises应力断裂判据的合理性。

英文摘要：

Based on the analysis of fractural mechanism of brittle materials, the concept of the radial plane maximum stress （RPMS） is presented. Under plane-strain condition, the stress distribution near the crack-tip is analyzed for mixed loading mode with different composite stress ratios in which the effect of Poisson＇s ratio is taken into account. Afterwards, the maximum Mises stress on the radial plane is taken as the key factor which governs the fracture behavior and crack initiation and the mixed fracture criterion on the basis of the radial plane maximum stress is proposed to consider the effect of three-dimensional stresses. As a result, the expression of crack initiation orientation is given. The results computed by the proposed method are compared with solution obtained by the conventional fracture theory and experimental data. It is shown that the proposed solution can give a good understanding of fractural mechanism and behavior of brittle materials under combined loading pattern.