金属内冲击波跨晶界传播的应力分配机制初探  

Preliminary Investigation on Stress Distribution Mechanism of Shock Propagating across Grain Interface in Metal

作　　者：王轩 黄生洪[1] 张永亮[1] WANG Xuan;HUANG Shenghong;ZHANG Yongliang(CAS Key Laboratory of Mechanical Behavior and Design of Materials,University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]中国科学技术大学材料力学行为与设计重点实验室

出　　处：《高压物理学报》2019年第5期34-45,共12页Chinese Journal of High Pressure Physics

基　　金：国防基础科学挑战计划(TZ2016001);国家自然科学基金委员会-中国工程物理研究院“NSAF”联合基金(U1530125)

摘　　要：冲击波跨越晶界过程中的应力分配机制对于深入理解冲击波与多晶金属材料的相互作用现象和塑性机理有重要意义。为探明该机制,采用分子动力学,对4种面心立方(FCC)晶格金属展开研究,细致统计分析了冲击波在单晶金属{100}晶面内随晶向角变化的应力生成特征及冲击波跨过单一晶界前后的应力状态和大小关系。结果表明:(1)垂直和平行于冲击波运动方向的应力分量随晶向角呈现不同的变化特征,这种应力生成差异的根源来自晶格原子排列导致的受力差异和原子间作用力机制,而其生成差异的结果恰恰是不同晶向塑性差异的主要原因;(2)弹性冲击波跨过单一晶界前后的应力状态存在一定的分配转换关系,由一个独立的应力分配张量D确定,不同FCC晶格元素的D张量形式一致,系数差异小,具有一定的通用特征;(3)验证表明,对于给定的FCC晶格金属,D具有一致的可预测特性,反映了冲击波与晶格相互作用的本质特征。To know the stress distribution mechanism of shock propagating across grain interface is of great significance to understand the interacting phenomena and plastic principles of shock and polycrystalline metal material.With molecular dynamics(MD),shock impacting on four kinds of metals with FCC(facecentered cubic)crystal lattice are numerically simulated.The stress tensor components distribution,scale and correlations of shock propagating in monocrystal and across grain interface on{100}lattice plane are computed and analyzed.It is concluded as follows:(1)The stress generated after shock propagating along different lattice arrangement orientations presents different characteristics between parallel and perpendicular shock direction,which is in accordance with force interaction difference due to the lattice arrangement and interaction mechanism between atoms.The results of such difference are corresponding to the plasticity variation with lattice orientations.(2)An independent tensor is found to be in charge of stress distribution in elastic shock propagating across a single grain interface.This tensor has uniform style and similar coefficients for different materials with the same lattice arrangement,presenting a kind of generality.(3)The coherent predictability and accuracy of stress distribution tensor for FCC lattice are validated by simulation results for shock impacting on a single grain interfaces at different velocities and lattice arrangement orientations,indicating the intrinsic property of the interaction between shock and lattice atoms.

关 键 词：多晶金属 冲击波 晶界 面心立方 应力 分子动力学 

分 类 号：O369[理学—流体力学]