Molecular Dynamics Simulations. Molecular Dynamics Simulation on Crack Growth in Amorphous Metal.
Molecular Dynamics Simulations. Molecular Dynamics Simulation on Crack Growth in Amorphous Metal.
复制标题
分子动力学模拟。
DOI：
10.2472/jsms.49.275
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Y. Sugiyama
中科院分区：
文献类型：
--
作者：
K. Nakatani;A. Nakatani;H. Kitagawa;Y. Sugiyama
非晶态金属的断裂通常以脆性方式发生。然而，这种金属本质上是一种延展性材料，因为尽管它具有高屈服强度，但它表现出高的变形性。乍一看，这两个事实似乎相互冲突。为了解决这一明显的矛盾，本文进行了原子模拟。采用分子动力学(MD)方法对含有102356个原子的非晶态结构进行了I型加载。当应力波到达裂纹尖端时，裂纹开始扩展。裂纹扩展量随裂纹尖端张开位移的增大而增大，势能随裂纹扩展而转变为动能。通过对缺陷原子的原子排列和结构(由局部密度定义)的研究表明，裂纹的扩展是在局部区域以延性方式发生的原子变形，但在宏观上是以脆性方式发生的。此外，研究还表明，在裂纹扩展过程中，裂纹与孔洞之间的相互作用在裂纹扩展过程中起着重要作用。
Fractures in amorphous metal usually occur in a brittle manner. The metal is, however, essentially a ductile material, for it demonstrates high deformability, despite having a high yield strength. These two facts seem to conflict with each other at first glance. In this paper an atomistic simulation is carried out to resolve this apparent contradiction. The molecular dynamics (MD) method is applied to a cracked amorphous structure containing 102356 atoms with mode I loading. Crack growth begins at the time when a stress wave arrives at the crack tip. The amount of crack extension increases with increase in the crack-tip opening displacement, and potential energy is changed to kinetic energy with the crack growth. From an investigation of the atomic arrangement and structure of the defect atoms (which is defined by a local density), it is demonstrated that crack growth occurs with atomic deformation that takes place in a ductile manner in a local area, but in a brittle manner in a macroscopic view. Moreover, it is shown that the interaction between the crack and the void, which develops in front of the crack tip, plays some important roles during crack growth.