基于微结构特征尺度和多场耦合效应热释电材料的三维断裂特性研究

As an important representative of a class of smart materials, thermopiezoelectric materials have excellent thermal-mechanical-electrical coupling effects, which have widely used in intelligent systems, such as sensors and actuators, etc. With the development of micro/nano technology, it is important that material is studied in microscale fracture behavior. But three-dimensional (3D) fracture behavior of thermopiezoelectric materials based on microstructure characteristic scale and multi-field coupling effects is still limited. By using theoretical analysis, numerical simulation and experimental methods, 3D fracture characteristics of thermopiezoelectric materials in microstructure characteristic scale and multi-field coupling effects will study in this project. The main contents are: a) 3D microscale mechanics model in piezothermoelastic materials is established, and the corresponding field intensity (heat flow field, stress field and electric displacement field) under different thermoelectric boundary conditions will obtained; b) by the simulation of the finite element method (ABAQUS), the fracture process of crack in thermopiezoelectric materials under microstructure characteristic scale is explored; c) by quasi-static test, the fracture behavior of thermopiezoelectric materials is verified. Finally, the influence of the geometry shape of crack, the geometry size of crack and the types of loading on fracture properties of the crack tip in thermopiezoelectric materials with different thermoelectric boundary conditions are obtained, and the effects of the microstructure characteristic parameter on field intensity at the crack tip are revealed. Then this project will provide an evaluation basis for microscale fracture mechanism and reliability analysis in thermopiezoelectric materials.

热释电材料作为智能材料的一类重要代表，其优良的热-力-电耦合作用被广泛用于传感器和制动器等智能系统。伴随微纳米技术的发展，材料在微尺度下的断裂行为研究显得越来越重要，但基于微结构特征尺度及多场耦合效应热释电材料的三维断裂行为研究仍然有限。本项目拟采用理论分析、数值模拟和试验相结合的方法，研究微结构特征尺度和多场耦合效应下热释电材料的三维断裂特性。主要内容有：建立热释电材料三维微尺度力学模型，获得不同热电边界条件下裂纹模型对应的场强度(热流场、应力场和电位移场)；探索有限元ABAQUS模拟微尺度下裂纹的断裂过程；采用准静态试验验证热释电材料的断裂行为。最终，获得不同热电边界条件下裂纹的几何形状、裂纹的几何尺寸以及载荷类型对热释电材料裂纹尖端断裂特性的影响，揭示微结构特征参数对裂纹尖端处场强度的影响规律，为微尺度下热释电材料的断裂机理及可靠性分析提供评价依据。

热释电材料在航天、航空以及军工领域有着广泛应用，当受到热载荷作用下，材料内部会出现温度的变化。同时，在压电器件及仪器制造使用的过程中，材料内部会产生热量，出现热膨胀现象，从而导致材料具有明显的热应力而变形。项目采用非局部连续介质力学理论、有限元模拟和三点弯曲试验，研究了基于微结构特征尺度和多场耦合效应热释电材料中矩形裂纹的三维断裂问题。利用非局部理论，给出了含矩形裂纹横观各向同性热释电材料和正交各向异性热释电材料静态断裂问题的非局部理论解，获得了裂纹边缘处非奇异热应力场和热电位移场；采用有限元软件ABAQUS数值分析了稳态温度场和热传导下，三维缺陷的形状（角缺陷、表面缺陷、内埋缺陷）对缺陷周围力电参数的影响规律；实验测试了在不同温度点压电试件准静态三点弯实验的载荷-位移结果。研究成果进一步加深微尺度下热释电材料断裂问题的认识，拓宽这一领域的研究范畴，为热释电材料及其相关电子器件的研发、设计和广泛的应用奠定一定的理论基础。项目在执行期间，在国内外学术期刊发表论文10篇，其中在高水平SCI期刊发表7篇，EI期刊发表论文3篇；发表会议论文2篇；参加国内学术会议14次；培养和在读硕士生10名。