Criterion of mechanical instabilities for dislocation structures

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:534

Article

Yan, Yabin¹  Kondo, Tadahiro¹  Shimada, Takahiro¹  Sumigawa, Takashi¹  Kitamura, Takayuki¹ 

[1] Kyoto Univ, Grad Sch Engn, Dept Mech Engn & Sci, Sakyo Ku, Kyoto 6068501, Japan

关键词: Criterion;    Instability;    Dislocation structure;    Vein;    Dislocation wall;    Deformation mode;    Dislocation theory;   

DOI  :  10.1016/j.msea.2011.12.027

来源: Elsevier

【 摘 要 】

To understand the nature of mechanical instabilities of dislocation structures, which plays a central role, for example, in determining the plastic behavior and fatigue in crystalline metals, it is essential to investigate a critical condition in which a dislocation structure collapses. A criterion for the mechanical instability of arbitrary dislocation structures is proposed in this paper. According to the criterion, the mechanical instability can be described by the positiveness of the minimum eigenvalue of the Hessian matrix, which is composed by the second-order differential of potential energy of the system with respect to the dislocation coordinates. In addition, the collapse mode can be simultaneously determined by the eigenvector of the minimum eigenvalue. We applied the proposed criterion to the veins and dislocation walls under external loading, and it successfully describes the onset of instabilities and the corresponding collapse modes, regardless of the difference in structures and sizes. This success in the criterion paves the way to address the mechanical instability issues on more complex dislocation structures. (C) 2011 Elsevier B.V. All rights reserved.

【 授权许可】

Free