Phase field analysis of crack tip parameters in ferroelectric polycrystals under large-scale switching
Phase field analysis of crack tip parameters in ferroelectric polycrystals under large-scale switching
复制标题
大尺度开关下铁电多晶裂纹尖端参数的相场分析
DOI：
10.1016/j.actamat.2018.05.042
复制
发表时间：
2018
期刊：
影响因子：
9.4
通讯作者：
Kuna Meinhard
中科院分区：
文献类型：
--
作者：
Yu Hongjun;Wang Jie;Kozinov Sergii;Kuna Meinhard
The determination of fracture parameters at cracks in ferroelectrics under large-scale domain switching is still a great challenge. In order to evaluate the crack-tip mechanical and electrical field intensity factors, the interaction integral (I-integral) technique is further developed to cope with the heterogeneous microstructures based on the polarization distribution and crack tip fields from phase field simulations. The enhanced I-integral exhibits several merits over previous techniques for determining the crack-tip intensity factors. First, small-scale switching assumption is unnecessary. Second, the intensity factors of different modes are decoupled. Third, it is independent of integration area size, regardless of the presence of grain boundaries and domain walls. These advantages ensure the successful application of the enhanced I-integral to study toughening effects in ferroelectric polycrystals due to large-scale domain switching. Using this approach, a tensile test of PbTiO3ferroelectric polycrystals with an impermeable crack is simulated. Simulations show that domain switching initiates not only from the crack tip but also from the grain boundaries due to high polarization gradient and stress concentration. Large-scale switching triggered by a critical load reduces the crack-tip stress intensity factors anomalously. In comparison to single crystals, the critical load for polycrystals is lower and even vanishes due to grain orientations. The results also demonstrate that the I-integral method possesses satisfactory accuracy and good area-independence for grain boundaries and domain walls.
