Molecular dynamics simulation of crack growth under cyclic loading
Molecular dynamics simulation of crack growth under cyclic loading
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DOI：
10.1016/j.commatsci.2004.03.009
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发表时间：
2004-11
影响因子：
3.3
通讯作者：
K. Nishimura;N. Miyazaki
中科院分区：
文献类型：
--
作者：
K. Nishimura;N. Miyazaki
使用分子动力学模拟检查循环载荷下包含裂纹和两个倾斜晶界的系统裂纹尖端周围的机械行为。不仅观察相变，而且观察边缘位错的发射，以便在第一次加载期间松弛裂纹尖端周围的应力集中。然后，在刃型位错到达晶界后，在晶界附近形成位错堆积，因为它们不能移动到晶界之外。在第一次卸载过程中，从裂纹尖端发射的刃位错返回到裂纹尖端并消失在系统中。我们观察到在循环加载过程中裂纹尖端周围产生了几个空位，并且裂纹扩展对应于原子尺度。最后，我们提出了疲劳断裂初始阶段的疲劳裂纹扩展机制。即，疲劳裂纹由于裂纹与位错的发射和吸收引起的空位的接合而扩展。
The mechanical behaviors around a crack tip for a system including both a crack and two tilt grain boundaries under cyclic loading are examined using a molecular dynamics simulation. Not only a phase transition but also the emission of edge dislocations is observed in order to relax stress concentration around a crack tip during the first loading. Then, a dislocation pile-up is formed near the grain boundary after the edge dislocations reach the grain boundary, because they cannot move beyond the grain boundary. During the first unloading, the edge dislocations emitted from the crack tip return to the crack tip and disappear in the system. We observe several vacancies generated around the crack tip and crack growth corresponding to an atomic scale during cyclic loading. Conclusively, we propose the fatigue crack growth mechanism for the initial phase of the fatigue fracture. That is, a fatigue crack propagates due to coalescence of the crack and the vacancies caused by the emission and absorption of dislocations.