Mechanism of electric fatigue crack growth in lead zirconate titanate
Mechanism of electric fatigue crack growth in lead zirconate titanate
复制标题
DOI：
10.1016/j.actamat.2006.08.029
复制
发表时间：
2007
期刊：
影响因子：
9.4
通讯作者：
I. Westram;W. Oates;D. Lupascu;J. Rödel;C. Lynch
中科院分区：
文献类型：
--
作者：
I. Westram;W. Oates;D. Lupascu;J. Rödel;C. Lynch
对铁电双悬臂梁 (DCB) 样本中的全厚度裂纹进行了一系列实验。施加不同幅度的循环电场，导致垂直于电场方向的循环裂纹扩展。通过光学观察裂纹扩展并确定了三种状态：从凹口弹出、稳态裂纹扩展以及裂纹扩展速率随着循环次数的增加而降低。仅当施加的场超过材料的矫顽场强度时，才会发生裂纹扩展。此外，裂纹在每次磁场反转期间扩展，并且裂纹扩展速率随着磁场的增加而增加。基于实验观察，我们形成了一种机理理解，并与量化 DCB 样本中应力强度的非线性有限元分析进行了对比。根据铁电转换引起的残余应力分布，计算了缺口处裂纹形成和随后的疲劳裂纹扩展的驱动力。有限元结果与实验观察结果非常吻合，并支持所提出的机制。
A series of experiments was performed with through-thickness cracks in ferroelectric double cantilever beam (DCB) specimens. Cyclic electric fields of different amplitudes were applied which resulted in cyclic crack propagation perpendicular to the electric field direction. Crack propagation was observed optically and three regimes were identified: a pop-in from a notch, steady-state crack growth and a decrease of the crack growth rate with increasing cycle number. Crack growth only occurred if the applied field exceeded the coercive field strength of the material. Furthermore, the crack extended during each field reversal and the crack growth rate increased with increasing field. Based on the experimental observations, a mechanistic understanding was developed and contrasted with a nonlinear finite element analysis which quantified the stress intensity in the DCB specimens. The driving forces for crack formation at the notch and subsequent fatigue crack growth were computed based on the distribution of residual stresses due to ferroelectric switching. The finite element results are in good agreement with the experimental observations and support the proposed mechanism.