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| Molecular dynamics simulation of fracture behavior and stress evolution of single crystal nickel with different initial defects |
| Received:June 15, 2022 Revised:July 17, 2022 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7511/jslx20220615002 |
| KeyWord:single crystal nickel microstructure fracture behavior stress distribution molecular dynamics simulation |
| Author | Institution |
| 李云丽 |
武汉工程大学 土木工程与建筑学院, 武汉 |
| 杨振睿 |
武汉工程大学 土木工程与建筑学院, 武汉 |
| 张学林 |
武汉工程大学 土木工程与建筑学院, 武汉 |
| 李嘉维 |
武汉工程大学 土木工程与建筑学院, 武汉 |
| 吴文平 |
武汉大学 土木建筑工程学院 工程力学系, 武汉 |
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| Abstract: |
| Fracture is a complex physical process across several different length scales.The fracture behavior at the macro-scale has been deeply studied and developed.However,there is a lack of in-depth understanding of the fracture behavior at the nanoscale and the change of stress field in the process of fracture.In this paper,the fracture behavior and stress distribution characteristics of single crystal nickel with different initial defects(sharp crack,blunt crack,and void) are studied by molecular dynamics(MD) simulation.The results show that different initial defects induce different fracture mechanisms,fracture strengths and fracture resistance.The single crystal nickel sample with a void has the highest fracture strength and fracture resistance,which is closely related to the formation of stacking faults in the process of void propagation.The sample with a blunt crack is next in magnitude of these properties,which is related to the crack tip blunts caused by [100] super-dislocations emission.The sample with a sharp crack shows a brittle fracture,and the atoms at the crack tip have no microstructure changes.This sample has the lowest fracture strength and fracture resistance.Moreover,different initial defects also cause the change of stress distribution during the fracture process.The high stresses(tensile stress,mean stress,von Mises stress) always occurs at the crack tip of the growing crack for the cleavage fracture sample with a sharp crack.While for the ductile fracture sample with a blunt crack or void,the high stresses occurs not only at the crack tip but also in the region of plastic deformation(dislocation emission and stacking faults formation).Before crack/void propagation,the stresses increase rapidly with the increase of loading time,and then almost stop increasing once the crack/void begins to propagate,and the value of tensile stress is always larger than that of mean stress and von Mises stress,which implies that the material failure at nanoscale under I loading condition is controlled by the tensile(normal) stress. |
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