Papers by Keyword: Three-Dimensional Cracks

Abstract: Three models including scheme A, B and C of the semicircular or crescent surface cracks, and two ones including scheme D and E of elliptical inner cracks in the vessel wall in three-dimensional are estabished with ABAQUS software. The values of the crack tip of the stress intensity factor are calculated and compared with the empirical results based on BS 7910 standard. The results show that scheme C and D are better, which provide a new method for the modeling and simulation of three-dimensional components containing cracks with finite element method.

Abstract: Using newly developed 3 dimensional Rock Failure Process Analysis code RFPA3D, numerical simulations on samples of rock-like material containing pre-existing surface closed flaws under uniaxial compressive loading are conducted to investigate the failure mechanism and crack coalescence modes. Friction in closed flaws is modeled by inserting ideal elasto-plastic materials into the flaws. The simulations replicate most of the phenomena observed in actual experiments, such as initiation and growth of wing and secondary cracks, crack coalescence, and the macro-failure of the sample. For the samples containing three pre-existing surface closed flaws, four different patterns of crack coalescence are obtained in our simulations. The four different patterns of coalescence are the combination of T mode, S mode, TS mode and C mode, i.e. type
(C+S mode), (T+S mode),  (S mode) and (C+S mode). A total of four types of samples containing three surface parallel inclined frictional flaws are numerically simulated.

Abstract: In order to simulate the growth of arbitrarily shaped three-dimensional cracks, the finite element alternating method is extended. As the required solution for a crack in an infinite body, the symmetric Galerkin boundary element method formulated by Li and Mear is used. In the study, a crack is modeled as distribution of displacement discontinuities, and the governing equation is formulated as singularity-reduced integral equations. With the proposed method several example problems, such as a penny-shaped crack, an elliptical crack in an infinite solid and a semi-elliptical surface crack in an elbow are solved. And their growth under fatigue loading is also considered and the accuracy and efficiency of the method are demonstrated.