核心区尺寸断裂判据

FRACTURE CRITERION OF CORE REGION SIZE

本文在修正Beltrami强度理论的基础上提出了一个新的复合断裂判据:当核心区最小尺寸的临界值r_(me)达到极限r_c时,裂纹将以核心中应变能密度最高的点开始沿最短路径向核心区边缘扩展。该判据能反映裂纹的开裂点,能体现非奇异应力对裂纹起裂的影响,能预言Ⅲ型裂纹的开裂方向。文中还用此判据分析了双向拉Ⅰ型裂纹、斜裂纹和Ⅰ—Ⅱ—Ⅲ复合裂纹,并同Sih判据进行了比较。

After modifying the Beltrami's failure theory, this paper proposed a new mixed fracture criterion that a crack will propagate along a shortest path from a point in the core region, at which the strain energy density is maximum to the boundary of core region, when the critical value of minimum size of core region, r_(me) reaches a limit r_C. The proposed criterion is capable of reflecting effects of nonsingular stresses on the propogation of a crack, of predicting the fracture direction of the Ⅲ-crack, and of determing the fracture point of a crack from the criterion. The peper also analyzed Mode Ⅰ-Ⅱ, Ⅰ-Ⅱ-Ⅲ cracks using the criterion, and compared it with the famous Sih' s criterion.