宏观尺度下固体电介质材料挠曲电效应实验方法及实验关键技术研究

Flexoelectricity describes the inhomogeneous strain field-induced (destroying the Centro-symmetry) electric polarization. The obtaining of flexoelectric coefficient in different dielectric materials is the main and key point of the research of the flexoelectricity. There are merely several experimental methods on measuring the certain flexoelectric coefficient components due to the complication of the flexoelectricity. The current researches lack the systematicness and integrity. Hence, the experimental method researches with their key technology development on solid dielectric materials are necessary and important. In this research, the experimental method research on both the flexoelectric and converse flexoelectric research are planned. Different flexoelectric coefficient components are needed to be originally obtained with novel method and special experimental devices. The already-known flexoelectric coefficient components are required to be researched in higher precision and optimized experiment method. In this research, the design of the specimens, the choice and optimization of load exerting method, the low cut off frequency-electric charge measurement, and the micro scale deformation detecting methods are required to be done. Based on the current experimental methods and technology, two types of solid dielectric materials are chose to research the flexoelectric and converse flexoelectric coefficient components, with the novel experimental devices and the newly-designed experiment methods. In this research, experimental method and the relating devices with higher precision will be presented. More flexoelectric coefficient components will be originally obtained experimentally in this research, which is support for the theory development of flexoelectricity and the application of it.

由非均匀应变场破坏反演对称而产生的电极化现象称为挠曲电现象，材料挠曲电系数的获取是挠曲电研究领域的重点与难点。由于挠曲电特性的复杂性，国内外现有实验方法仅能测量几个典型系数分量，缺乏系统性和完备性。因此，本研究拟针对宏观尺度下固体电介质材料挠曲电系数的测量方法和实验的关键技术展开研究。拟通过经典力学理论、电磁场理论，结合挠曲电理论进展及各系数分量的特点，设计和优化正、逆挠曲电系数测量的实验方法，实现挠曲电系数分量的准确测量和进一步研究；针对实验需求，对试件应变梯度设计、加载模式、极低频微小电荷测量、微小形变测量等关键技术展开研究。在已有测量方法研究的基础上，针对陶瓷材料及高分子聚合物两类材料的不同挠曲电系数分量开展相应的实验方法研究，研制出相应的实验仪器，提供精度更高的加载和测量实验方法和手段。本项目将获得更多目前尚未得到的挠曲电系数分量，为挠曲电理论的进一步发展和应用提供技术支撑。

力-电耦合效应及其材料研究是满足航天结构在轨精指向调节、智能振动控制等国家重大战略需求的重要内容，而挠曲电效应因其尺寸相关性、宽使用温度范围和力学可设计性等优势越来越多地受到关注。本课题项目名称为宏观尺度下固体电介质材料挠曲电效应实验方法及实验关键技术研究，基本任务为在宏观尺度下对固体电介质材料的挠曲电效应开展实验方法研究，其中包括设计和研发挠曲电效应激励和测试系统、设计实验方法、搭建实验系统、突破实验关键技术、及对宏观尺度下固体介电材料的挠曲电效应开展系统性实验研究。本课题圆满地完成了预期任务，其中包括；研制了实验专用的挠曲电效应的激励和测试系统，完成了纵向、横向和剪切向挠曲电效应的系统性实验研究、挠曲电效应解耦研究、逆挠曲电效应及其作动器研究、挠曲电效应增强研究等。相关研究填补了宏观尺度下挠曲电效应实验研究相关设备的空白，以直线式微位移作动器为例，其输出力600 N、开环输出精度优于0.1 m，行程超过1 mm；实现了低对称性固体电介质材料挠曲电系数实验研究系统性研究；利用联立耦合实验的方法解耦了挠曲电系数、获取了本征挠曲电系数并掌握了相关研究方法，确定了解耦后的挠曲电系数值为10-9~10-10 C/m数量级；利用逆挠曲电效应实现了挠曲电作动器，作动精度优于1 nm；利用介电常数梯度、几何结构设计等方法实现了挠曲电效应的增强，增强后的等效挠曲电效应比原效应高出一个数量级。相关研究为挠曲电效应研究向微观尺度进展和应用研究，包括基于航天器结构精指向调节和微振动控制的微小位移作动器和高精度力学量传感器等研究提供了重要支撑。