柔性无机压电器件力电耦合行为的材料非线性效应影响研究

Nonlinearity is the intrinsic property of the piezoelectric materials. However, the linear constitutive relations are mostly used when analyzing the electromechanical behaviors of flexible inorganic piezoelectric devices, which brings great challenges to the predicting the performance of these devices. For example, the deviation between experimental and theoretical values of the output power may be as high as 74%. In this project, two typical flexible piezoelectric devices, i.e., nanowire/nanobeam/nanofilm and stiff thin films bonded on soft substrates, are taken as the research objects. The influences of the material nonlinearity on the static electromechanical behaviors of the devices, such as buckling (critical buckling loads, critical buckling voltages, critical buckling strain, etc.) and post-buckling behaviors (shapes, amplitudes, etc.), are studied. Furtherly, the effects of the material nonlinearity on the dynamic electromechanical behaviors, such as the resonant frequency and the frequency responses of the devices, are investigated. The surface effects and nonlinear large deformation are also considered when necessary. Based on these analyses, the analytical models of electromechanical behaviors with nonlinear constitutive relationships and the regulation models of performances of the flexible inorganic piezoelectric devices while serving as actuators, sensors and energy harvesters are established. The theoretical analyses, FEM simulations and the corresponding experiments are carried out to address this problem. The accomplishment of this project will provide more accurate theoretical supports for the analyses of the static and dynamic electromechanical behaviors, the performance predictions, and the design optimizations of the flexible inorganic piezoelectric devices.

非线性是压电材料的固有特性，然而目前柔性无机压电器件力电耦合行为的研究主要采用线性材料本构，这给器件的服役性能预测带来巨大挑战（如能量收集功率预测误差可达74%）。本项目以纳米线/梁/薄膜和硬膜软基底的两类柔性压电器件为研究对象，综合考虑其独特的非线性大变形和尺寸效应，揭示材料非线性对器件屈曲（临界屈曲荷载、电压、应变等）、后屈曲（后屈曲构型、幅值等）等静态力电耦合行为和共振频率、频响等动态力电耦合行为的影响机制，从而构建基于材料非线性本构的器件力电耦合行为分析模型和服役性能（作动、传感和能量收集）调控模型。项目拟在理论分析基础上开展有限元模拟和实验测试。该项目实施将为柔性无机压电器件的静动态力电耦合行为分析、服役性能预测评估和一体化设计提供理论支撑。

柔性无机压电器件在生物能量收集和生理信号传感等领域具有显著优势，然而其力电耦合行为，尤其是材料非线性力电耦合行为的研究尚待深入。针对此问题，开展四部分研究内容：①高灵敏度柔性压电器件的制备，②强非线性压电材料的测试分析，③柔性压电器件用于心脏形变监测及心动能量收集中的力电耦合问题，④压电器件在道路能量收集中的力电耦合行为分析。研究发现压电材料非线性对能量收集效率和传感器的灵敏度、检测下限等参数提升具有显著影响。该项目研究推进了压电材料在心动能量收集、心脏形变监测、人体生理信息监测、道路能量收集等方面的多场耦合力学理论的应用。