Hydraulically pumped cone fracture in brittle solids
Hydraulically pumped cone fracture in brittle solids
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DOI：
10.1016/j.actamat.2005.05.026
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发表时间：
2005-09-01
期刊：
影响因子：
9.4
通讯作者：
Lawn, BR
中科院分区：
文献类型：
--
作者：
Chai, H;Lawn, BR
本文分析了脆性固体在液体中循环压入下的内锥裂纹。这些内锥裂纹，如此命名是因为它们形成在最大接触圆内，被假定为由液压泵送机构驱动。与传统的外锥裂纹对应物不同，内锥在没有液体的情况下不会出现单调加载甚至循环加载。根据液压泵送假设，膨胀接触吞没表面裂缝或缺陷，关闭裂缝口并将截留的液体挤压向地下尖端，从而增强向下渗透。以水中球形压头加载的钠钙玻璃为例，采用有限元模型分析了裂纹扩展附近的应力场和位移场，并计算了应力强度因子。一个逐步递增的过程确定了内锥裂纹的演变，即，对于该系统，裂纹深度c是压痕循环次数n的函数。预测的c（n）响应再现了实验观察到的行为的基本特征，相对于同伴外锥裂纹：值得注意的是，在赫兹应力支配的初始区域中缓慢启动，随后随着液压泵的激活而快速加速，最终在稳态远场中占主导地位。由Elsevier Ltd代表Acta Materialia Inc.发布
An analysis of inner cone cracks in brittle solids subject to cyclic indentation in liquid is presented. These inner cone cracks, so named because they form well within the maximum contact circle, are postulated to be driven by a hydraulic pumping mechanism. Unlike their more traditional outer cone crack counterparts, inner cones do not appear in monotonic loading or even cyclic loading in the absence of liquid. According to the hydraulic pumping postulate, an expanding contact engulfs surface fissures or flaws, closing the crack mouths and squeezing entrapped liquid toward the subsurface tips, thereby enhancing downward penetration. Finite element modeling is used-to analyze the stress and displacement fields in the vicinity of the growing cracks and to compute stress intensity factors, using soda-lime glass loaded by a spherical indenter in water as a case study. A stepwise incrementing procedure determines the inner cone crack evolution, i.e., crack depth c as a function of number of indentation cycles n, for this system. The predicted c(n) response reproduces essential features of experimentally observed behavior, relative to companion outer cone cracks: notably, a sluggish start in the initial regions, where Hertzian stresses govern, followed by rapid acceleration as hydraulic pumping activates, ultimately dominating in the steady-state far-field. Published by Elsevier Ltd on behalf of Acta Materialia Inc.