| 摘要(英) |
This thesis studies mechanical behavior and failure process of a thin notched plate subjected to uniaxial tension using the discrete element method (DEM). The purpose of this study is to investigate the effects of crystal structure and notch inclination angle on the mechanical responses, crack initiation and propagation process, and crack paths. The proposed DEM model has been verified by the corresponding FEM calculation. The main findings are highlighted as follows: (1) The force-displacement curves for each crystal structure all exhibit wavy profiles and the loading stiffnesses of the curves follow the sequence of hexagonal close-packed (HCP) > face-centered cubic (FCC) > simple cubic (SC) > body-centered cubic (BCC); (2) The stress concentration factor first increases with notch inclination angle, reaches the maximum value (at the notch inclination angle of 30 degrees) and then decreases to the minimum value (at the notch inclination angle of 90 degrees); (3) In general, for the same crystal structure, the larger the stress concentration factor is, the smaller the fracture force is; (4) For the same notch inclination angle, the magnitude order of the boundary displacement is as follows: BCC>SC>FCC>HCP; (5) For all the four crystal structures, the maximum stored strain energy occurs at the notch inclination angle of 90 degrees but the minimum is at the different angle for each crystal structure; (6) The crack generally developed and propagated along the horizontal direction, and the region behind the crack tip shows the compressive contact forces; (7) The SC and BCC crystal structures show a symmetric feature of crack propagation, whereas the FCC and HCP crystal structures exhibit asymmetric characteristics; (8) In such a loading scenario, a plate with an inclined notch subjected to uniaxial tension, the crack initiation and propagation in all the four crystal structures are mainly dominated by the tension mode. |
| 參考文獻 |
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