非均質ボクセル要素を用いた超並列有限要素解析によるアルミニウム鋳造合金のき裂起点介在物の応力評価

抄録

Fatigue crack in cast aluminum alloys subjected to low-cycle fatigue is initiated mainly by the fracture of Si particles. We addressed the mechanism of Si particle fracture through fatigue testing and in situ CT scanning, and the large scale image-based finite element analysis. The fracture of Si particle in the crack initiation site was detected from chronological CT observation. The large scale finite element analysis, where the number of element was about 150 million, was conducted by using CT images which was extracted to contain crack initiation site. To generate the finite element mesh automatically, the heterogeneous voxel element was employed. Moreover, the small scale analysis with 10-node tetrahedral element was performed to compare the results of large scale analysis. The large scale finite element analysis and its post-processing were performed on the supercomputers by the massively-parallel computing. The result of finite element analysis showed that the first principal stress of the interested Si particle was higher inside the specimen than in the surface of the specimen since the geometrical constraint was generated from the normal strain to the loading axis. Moreover, the first principal stress of the interested Si particle increased in neighbor of the surface of specimen under cyclic loading while the stress of Si particles inside the specimen and at the corner of specimen decreased.