Calculation method of fracture toughness of materials at transition state

The fracture toughness of materials is very important for damage tolerance design and assessment technology, while the test method to obtain the fracture toughness in the transition state is costly and time-consuming. In order to overcome these disadvantages, a determination method of fracture toughness based on calculation in the transition state was presented. The triaxial stress constraint parameter for the three-dimensional crack tip was analyzed, the relation between fracture toughness and material tensile properties was researched with the energy criterion for material fracture, meanwhile the relation expression in the three-dimensional stress state for I type crack fracture and the determination method of fracture toughness of materials based on calculation in the transition state were obtained. The fracture toughness in the transition state for 2219-T87 aluminum alloy was calculated with the determination method and empirical formula most of the theoretical calculation values were safer compared with test results and smaller than the values calculated by the empirical formula. ©, 2015, Beijing University of Aeronautics and Astronautics (BUAA). All right reserved.