考虑挠曲电和表面效应的压电纳米俘能器力电耦合特性研究

Piezoelectric nano-energy harvesters are significant in the applications of wireless sensor networks, mobile devices, implantable medical devices etc. It has been demonstrated that piezoelectric nanostructures are capable of converting mechanical energy into electrical energy. However, the qualitative and quantitative descriptions of the electromechanical coupling properties of piezoelectric nanomaterials and the energy conversion mechanism of piezoelectric nano-energy harvesters are still limited. Based on the piezoelectric beam and plate theories with the consideration of the flexoelectricity and the surface effects, this project aims to develop mechanics models for piezoelectric nano-energy harvesters built on piezoelectric nanowires, nanoscale piezoelectric thin films and wavy piezoelectric nanoribbons. Through analytical and numerical analyses, we will exam (1) the electromechanical coupling fields, generated electric charge, electrical voltage and electrical energy of the piezoelectric nano-energy harvesters under quasi-static stimuli; (2) the electromechanical coupling fields, current, electrical voltage and power density under dynamic stimuli; (3) the size-dependent properties of the electromechanical coupling properties and the output electrical quantities of the piezoelectric nano-energy harvesters due to the flexoelectricity and the surface effects. Besides, simulation results will be adopted to design piezoelectric nano-energy harvesters with better performance and flexoelectricity-based nano-energy harvesters. This study will help understanding the electromechanical coupling properties of the piezoelectric nanostructures and provide guidelines for the design and the development of nano-energy harvesters.

压电纳米俘能器在无线传感器网络、移动设备、植入医疗器械等领域中有着重要的应用前景。试验证明基于不同压电纳米结构可将机械能转换为电能。然而，有关纳米尺度压电材料力电耦合特性和压电纳米俘能器能量转换的定性定量描述还很有限。本项目拟针对不同压电纳米俘能器的俘能结构，包括纳米线、纳米薄膜和波浪状纳米带，考虑挠曲电和表面效应，建立基于压电梁、板理论的压电纳米俘能器力学模型，并通过理论与数值方法研究（1）准静态激励下俘能器的力电耦合场及其产生的电荷、电压和电能；（2）动态激励下俘能器的力电耦合场及其输出的电流、电压、功率密度和能量转换率；（3）挠曲电和表面效应引起的俘能器力电耦合场和电输出的尺寸依赖性。此外，数值仿真结果还将用于设计高性能压电纳米俘能器和挠曲电式纳米俘能器。本项目的开展，不仅能加深人们对纳米尺度力电耦合特性的认识，还有助于纳米俘能器的设计与开发。

新型微纳米智能器件在无线传感器网络、移动设备、植入医疗器械等领域中有着重要的应用前景，制约其应用的核心问题是供能问题，利用材料的力电耦合效应，将环境中的机械能转换成电能是实现能量自供的最佳方式。本项目开展了考虑挠曲电和表面效应的压电纳米结构力电耦合特性研究，重点开展了基于纳米尺度梁、板结构压电/挠曲电式俘能器能量转换定性定量研究。主要研究成果包括：建立了考虑挠曲电效应、表面效应和非局部弹性效应的压电纳米材料修正连续介质力学模型，推导了压电纳米圆板控制方程，研究了压电纳米圆板尺寸依赖弯曲与振动特性；得到了介电纳米环力电耦合场解析表达式；基于Euler-Bernoulli梁假设和二维板理论，建立了考虑表面效应和挠曲电效应的纳米梁俘能器模型、压电/压磁双层板俘能器模型，推导了耦合控制微分方程，研究了不同参量对俘能器电输出、磁电耦合系数的影响；考虑几何非线性和挠曲电效应，建立了载荷激励下俘能器模型, 推导了非线性耦合控制方程，研究了俘能器的非线性电输出特性；建立了挠曲电效应和静电效应驱动的开关模型，研究了挠曲电效应影响下纳米开关临界电压和临界挠度。相关研究结果对理解微纳尺度力电耦合效应、设计微纳米俘能器有一定的指导意义，为微纳尺度介电材料多场耦合特性及其应用研究打下了基础。