Effect of large-scale domain switching on intensity factors for a crack in 3D ferroelectric single crystals using the I-integral method
Effect of large-scale domain switching on intensity factors for a crack in 3D ferroelectric single crystals using the I-integral method
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使用 I 积分法研究大尺度畴切换对 3D 铁电单晶裂纹强度因子的影响
DOI：
10.1016/j.ijsolstr.2018.11.015
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发表时间：
2019-04
影响因子：
3.6
通讯作者：
Kozinov Sergii
中科院分区：
文献类型：
--
作者：
Yu Hongjun;Kuna Meinhard;Kozinov Sergii
铁电材料由于其固有的脆性，在极端的机电操作载荷下容易断裂。铁电材料的断裂通常伴随着大尺度的畴变。本文通过对裂纹的当前状态施加虚拟载荷增量，发展了三维铁电体裂纹的相互作用积分方法。与广泛使用的开关增韧模型不同，I积分不限于小尺度开关。由于虚拟载荷增量的可设计选择，I积分允许解耦不同断裂模式的强度因子。由于I积分与积分体积无关，因此可直接提取弯曲裂纹前缘沿着的局部强度因子。由于这些优点，I积分方法在大尺度畴变下的铁电体断裂分析中是一种很有前途的方法。此外，将I积分方法与相场模型相结合，模拟了具有半圆形表面裂纹的纳米级PbTiO 3铁电单晶的拉伸实验.结果表明，当外加载荷超过某一临界值时，极化对出现不同的模式。裂纹所在平面将稳定畴结构分为两层，每层中最终形成多个极化涡。除了几何和加载条件外，裂纹前缘相对于极化涡的位置是影响应力强度因子变化的关键因素。
Due to their intrinsic brittleness, ferroelectric materials are prone to fracture under extreme electromechanical operational loads. The fracture of ferroelectric materials is usually accompanied by large-scale domain switching. This paper develops the interaction integral (I-integral) method for a crack in three-dimensional ferroelectrics through applying a virtual load increment to the current state. Unlike the widely-used switching-toughening model, the I-integral is not restricted to small scale switching. Due to designable choice of the virtual load increment, the I-integral allows to decouple the intensity factors of different fracture modes. The local intensity factors along the curved crack front can be directly extracted, since the I-integral is independent of integration volume. With these merits, the I-integral method is a very promising technique in fracture analysis of ferroelectrics under large-scale domain switching. Moreover, the I-integral method is used in combination with the phase field model to simulate a tensile test of nanoscale PbTiO3ferroelectric single crystal with a semi-circular surface crack. Results show that various patterns of polarization pairs appear as soon as the applied load is increased beyond a critical value. The stable domain structures are divided into two layers by the plane where the crack is located and in each layers several polarization vortices formed eventually. Apart from the geometry and loading conditions, the position where the crack front is located with respect to the polarization vortex is a key factor affecting the switching-induced change of the stress intensity factor.
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