Effect of imperfections on the yielding of two-dimensional foams
Effect of imperfections on the yielding of two-dimensional foams
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DOI：
10.1016/s0022-5096(99)00030-7
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发表时间：
1999-11-01
影响因子：
5.3
通讯作者：
Fleck, NA
中科院分区：
文献类型：
--
作者：
Chen, C;Lu, TJ;Fleck, NA
本文系统地研究了六种不同类型的形态学缺陷-波纹度、不均匀的细胞壁厚度、细胞尺寸变化、破裂的细胞壁、细胞壁错位和缺失的细胞-对二维多孔固体屈服的影响。重点放在量化这些缺陷的击倒效果的流体静力学屈服强度和理解相关的变形机制。在本研究中的模拟表明，高的流体静力学强度，理想的蜂窝体的特性，降低到一个水平与偏强度由几种类型的缺陷。这种大的击倒的共同来源是在流体静力学载荷下从细胞壁拉伸到细胞壁弯曲的变形模式的切换。断裂的泡孔边缘对2D泡沫的屈服强度产生最大的击倒效应，然后依次是缺失泡孔、波浪形泡孔边缘、泡孔边缘错位、Gamma Voronoi泡孔、Delta Voronoi泡孔和不均匀壁厚。一个简单的椭圆屈服函数与两个可调的材料参数成功地适合数值预测的屈服面不完美的2D泡沫，并显示出潜在的唯象本构律，以指导由金属泡沫结构部件的设计。(C)1999 Elsevier Science Ltd.保留所有权利。
The influence of each of the six different types of morphological imperfection-waviness, non-uniform cell wall thickness, cell-size variations, fractured cell walls, cell-wall misalignments, and missing cells-on the yielding of 2D cellular solids has been studied systematically for biaxial loading. Emphasis is placed on quantifying the knock-down effect of these defects on the hydrostatic yield strength and upon understanding the associated deformation mechanisms. The simulations in the present study indicate that the high hydrostatic strength, characteristic of ideal honeycombs, is reduced to a level comparable with the deviatoric strength by several types of defect. The common source of this large knock-down is a switch in deformation mode from cell wall stretching to cell wall bending under hydrostatic loading. Fractured cell edges produce the largest knock-down effect on the yield strength of 2D foams, followed in order by missing cells, wavy cell edges, cell edge misalignments, Gamma Voronoi cells, delta Voronoi cells, and non-uniform wall thickness. A simple elliptical yield function with two adjustable material parameters successfully fits the numerically predicted yield surfaces for the imperfect 2D foams, and shows potential as a phenomenological constitutive law to guide the design of structural components made from metallic foams. (C) 1999 Elsevier Science Ltd. All rights reserved.