关键词: 最大周向应力准则, 复合型裂纹, T应力, 断裂韧性, 裂纹扩展

Abstract: In order to improve the prediction accuracy of crack-propagation of composite elastic material by the MTS criterion, we propose a generalized MTS(GMTS) criterion after considering the role of T-stress in brittle fracture. The new criterion can describe type Ⅰ and type Ⅱ stress intensity factors, fracture toughness of KⅠ, KⅡ, the T-stress paralleled to the crack, and influence of radius of critical fracture propagation zone on crack propagation, so the T-stress can help to study the stress field of crack tip more accurately. It’s concluded that the initial crack angle increased with the increase of crack inclination by considering T-stress. Compared with prediction results by GMTS (Generalized Maximum Tensile Stress) criterion, the initial fracturing angle predicted by MTS criterion was larger and more sensitive to the change of T-stress when the crack angle β>45°, however when β<45° the initial fracturing angle predicted by MTS criterion was smaller and less influenced by the changing of T-stress; For the composite cracks, the fracture angles calculated by GMTS criterion were different from that of traditional MTS criterion. Because brittle fracture’s propagation is controlled by a combination of singular stresses (K) and non-singular stress (T-stress), so stress field estimation on crack tip could be improved by considering higher order terms of the Williams series solution.

Key words: maximum circumferential stress, composite fracture, T-stress, fracture toughness, crack propagation