Atomistic simulations of elastic deformation and dislocation nucleation in Al under indentation-induced stress distribution
Atomistic simulations of elastic deformation and dislocation nucleation in Al under indentation-induced stress distribution
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DOI：
10.1088/0965-0393/14/5/s07
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发表时间：
2006-07-01
影响因子：
1.8
通讯作者：
Shibutani, Yoji
中科院分区：
文献类型：
--
作者：
Tsuru, Tomohito;Shibutani, Yoji
为了揭示纳米压痕下弹性变形和初始塑性的内应力状态，采用分子动力学方法对不同球面压痕半径下的简单剪切变形和压痕进行了初步模拟。在一组模拟中，提出了一个包含多达1,372,000个原子的原子单晶铝模型和一个理想的无摩擦球形压头。重点讨论了不同压头球面半径的应力分布对位错发射临界条件的影响。压痕下位错发射的临界剪切应力与压痕诱导应力状态下的等效外力作用下的简单剪切变形下的剪切强度基本一致。结果表明，抗剪强度很大程度上取决于外部应力分量，因此，压头下方产生的高压应力状态导致临界剪切应力远高于mu/2 pi。
Preliminary simulations of simple shear deformation and indentation simulations using different radii of a spherical indenter are performed using molecular dynamics in order to uncover the internal stress state for elastic deformation and subsequent initial plasticity under nano-indentation. An atomic single-crystalline aluminium model containing up to 1,372,000 atoms and an ideal friction-free spherical indenter are presented in a set of simulations. Effects of the stress distribution using several kinds of spherical radii of indenters on the critical condition of dislocation emissions are discussed with much emphasis. The critical shear stress for the dislocation emission under indentation is well accorded with the shear strength under the simple shear deformation exposed to the equivalent external stresses to the indentation-induced stress states. It is confirmed that shear strength strongly depends on the external stress component and therefore, high compressive stress states generated beneath the indenter lead to the much higher critical shear stress than mu/2 pi.