Spherical indentation of porous ceramics: Cracking and toughness
Spherical indentation of porous ceramics: Cracking and toughness
复制标题
DOI：
10.1016/j.jeurceramsoc.2016.05.010
复制
发表时间：
2016-11-01
影响因子：
5.7
通讯作者：
Brandon, Nigel
中科院分区：
文献类型：
--
作者：
Chen, Zhangwei;Wang, Xin;Brandon, Nigel
采用实验与数值相结合的方法，模拟了孔隙率为5- 45%的多孔陶瓷块体材料（La_（0.6）Sr_（0.4）Co_（0.2）Fe_（0.8）O_3）在球形压痕作用下的断裂过程。在有限元分析中采用Gurson模型来描述孔隙致密化过程。当接触压力超过临界值时，压痕引起的径向裂纹出现，没有发现赫兹环锥裂纹;有限元分析表明，裂纹主要在卸载过程中扩展，受接触圆附近产生的拉应力驱动。在裂纹尖端的应力强度估计使用有限元应力场的近似分析，以获得与由传统方法确定的值一致的韧性值，只要裂纹长度是足够大的接触半径相比，可以准确地测量。加载过程中没有环锥裂纹是由于材料的高模量-硬度比和小压头半径，如已建立的理论所预测的。(C)2016作者由爱思唯尔有限公司出版。这是一篇开放获取的文章，使用CC BY许可证（http：//creativecommons.org/licenses/by/4.0/）。
A combined experimental-numerical approach is used to characterise the fracture of a porous bulk ceramic material (La0.6Sr0.4Co0.2Fe0.8O3) with porosities of 5-45%, undergoing spherical indentation. The Gurson model was used in FEM to describe the porosity densification. Indentation-induced radial cracks were observed, when the applied contact pressure exceeded threshold values, with no Hertzian ring-cone cracks found. FEM analysis indicated that the cracks propagated mainly during unloading, driven by the tensile hoop stress generated near the contact circle. The stress intensity at the crack tip was estimated using an approximate analysis of the FEM stress field to derive toughness values that were consistent with values determined by conventional methods, provided that the crack length is sufficiently large compared with the contact radius and can be measured accurately. The absence of ring-cone cracks during loading is due to the material's high modulus-to-hardness ratio and the small indenter radius as predicted by established theory. (C) 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).