Size effects on stress concentration induced by a prolate ellipsoidal particle and void nucleation mechanism
Size effects on stress concentration induced by a prolate ellipsoidal particle and void nucleation mechanism
复制标题
长椭球颗粒引起的应力集中的尺寸效应和空洞成核机制
DOI：
10.1016/j.ijplas.2004.07.006
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发表时间：
2005-01-01
影响因子：
9.8
通讯作者：
Li, ZH
中科院分区：
文献类型：
--
作者：
Huang, MS;Li, ZH
材料中普遍存在两种空穴形核机制，即硬第二相颗粒的破碎和颗粒-基质界面的分离。颗粒形状在控制空穴形核机制中的作用已经在文献中得到了仔细的研究。在这项研究中，颗粒大小和形状对空穴形核机制的耦合效应尚未得到仔细的研究，但特别受到关注。为此，广泛的颗粒长宽比(但仅限于长球形颗粒)被认为反映了形状效应；尺寸效应被Fleck-Hutchinson唯象应变塑性本构理论捕获(应用力学进展，第33卷，学术出版社，纽约，1997年，第295页)。对含有孤立弹性长球形颗粒的无限大块进行了详细的理论分析和计算，揭示了基质-颗粒界面和颗粒内部的应力集中及其分布特征。得到了一些与尺度无关情况不同的结果：(1)颗粒-基质界面的最大应力集中系数(SCF)随着尺寸效应的增加而显着增加，尤其是细长颗粒。这可能会通过解理或原子分离在基质-颗粒界面触发空穴形核。(2)在给定的总有效应变下，颗粒尺寸效应显著提高了基体-颗粒界面的应力水平。这意味着尺寸效应可能会在较小的总应变下推进界面分离。(3)对于尺度无关的情况，细长颗粒的断裂通常发生在界面脱粘之前。对于比例相关的情况，尽管粒子内的SCF也因粒子尺寸效应而增大，但界面上的SCF上升的速度要快得多。结果表明，界面分离导致空洞形核的概率增大。(C)2004爱思唯尔有限公司。保留所有权利。
There generally exist two void nucleation mechanisms in materials, i.e. the breakage of hard second-phase particle and the separation of particle-matrix interface. The role of particle shape in governing the void nucleation mechanism has already been investigated carefully in the literatures. In this study, the coupled effects of particle size and shape on the void nucleation mechanisms, which have not yet been carefully addressed, have been paid to special attention. To this end, a wide range of particle aspect ratios (but limited to the prolate spheroidal particle) is considered to reflect the shape effect; and the size effect is captured by the Fleck-Hutchinson phenomenological strain plasticity constitutive theory (Advance in Applied Mechanics, vol. 33, Academic Press, New York, 1997, p. 295). Detailed theoretical analyses and computations on an infinite block containing an isolated elastic prolate spheroidal particle are carried out to light the features of stress concentrations and their distributions at the matrix-particle interface and within the particle. Some results different from the scale-independent case are obtained as: (1) the maximum stress concentration factor (SCF) at the particle-matrix interface is dramatically increased by the size effect especially for the slender particle. This is likely to trigger the void nucleation at the matrix-particle interface by cleavage or atomic separation. (2) At a given overall effective strain, the particle size effect significantly elevates the stress level at the matrix-particle interface. This means that the size effect is likely to advance the interface separation at a smaller overall strain. (3) For scale-independent cases, the elongated particle fracture usually takes place before the interface debonding occurs. For scale-dependent cases, although the SCF within the particle is also accentuated by the particle size effect, the SCF at the interface rises at a much faster rate. It indicates that the probability of void nucleation by the interface separation would increase. (c) 2004 Elsevier Ltd. All rights reserved.