傾斜機能材の高速き裂進展現象に対する移動有限要素法の開発

概要

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In the fracture problems in the functionally graded materials (FGMs), singular deformation field near the crack tip is appeared in the gradient field of material properties. In the finite element analyses for the fracture of FGMs, this complex fracture behavior has to be solved by using fine mesh subdivision. In this study, the moving finite element method is devoloped to simulate fracture behavior of four points bending specimen consists of the FGM. In the moving finite element method based on the Delauney automatic triangulation, effective mesh subdivision is updated with crack propagating. The T^* integral is used as criterion to evaluate crack tip condition, because the material properties distribution in FGMs has to be considered to derive exact crack tip parameter. Far-field path independence of the T^* integral is mathematically proved for the fracture in the FGM. The path independence of the T^* integral is also confirmed from the numerical results of the moving finite element analyses. This numerical prediction is demonstrated for four point bending fracture in FGMs. Based on the T^* integral and stress intensity factor, crack propagation path is predicted by the localy symmetry condition. The numerically predicted crack propagation path is compared with experimental result.
2010-11-25