摘要
力学量的传感与测量技术在国防、航天航空、能源等重点领域发挥着基础而重要的作用,如空天环境中监测航天结构微振动、测量航空发动机关键部位参数变化、监测各类管道应力变化等等。压电材料由于其优秀的力-电转换能力和传感无源性而广泛应用于各类力学量传感器中。然而由于其选材受限、效应随时间衰减、受居里温度限制、力-电耦合关系非线性、材料含重金属等,难以满足不断增长的技术参数需求和对环境保护的诉求。挠曲电效应是一种广泛存在于所有电介质材料中、由应变梯度引发的电极化现象。由于挠曲电效应存在范围极广、效应不随时间变化、不受居里温度限制、力电耦合关系线性度好、材料和器件可设计性强,且由于该效应是应变梯度相关、具有明显的小尺寸效应等独特优势,因此挠曲电效应,尤其是固体材料挠曲电效应的研究具有非常重要的科研和应用价值。在宏观尺度下研究固体电介质材料具有以下重要意义:在宏观尺度下,由于静电力、表面效应、特征尺度等微观因素对实验的影响较小以至于忽略不计,因此能够得到更加真实的挠曲电效应;能够验证和发展为尚待完善的挠曲电相关理论;能够为未来在微纳尺度下进行挠曲电效应的实验研究打下技术基础,积累相关经验;能进一步支持和促进基于挠曲电原理的应用研究。本文拟通过以下几部分对主题内容展开阐述:挠曲电效应的起源、发展阶段与在工程应用中的重要意义;挠曲电实验研究的实验方法及其优化;挠曲电的系数研究进展;基于挠曲电原理的应用研究进展。最后对挠曲电效应的发展情况进行展望。
The measurement science and technology of the mechanical loads is vital to various fields such as military, aerospace, energy, such as the micro-vibration on the large satellite/structure, the detection of the key points of the aero-engine, and pipeline inner stress ratio monitoring. Piezoelectric materials have been widely adopted in the above mentioned fields as their advancedelectro-mechanical altering ability and the advantage of the passive phenomenon in the sensing unit. The growing requirement of the higher technologic parameters and the environment protection has conflicts on the disadvantage of the material selection, the effect-time decreasing, the temperature limitations, non-linear relationship of the electro-mechanic loads, and the heavy metals inside the piezoelectric materials. Flexoelectricity, a strain gradient induced polarization, however, is a wide existing electro-mechanical phenomenon in all dielectric materials, with its effect consistency, no limitation of Curie temperature, good linearity and designable both in material and in structure. What is more, as this effect is size-related. This means that the device will behave much better in micro scales. The above mentioned properties makes the research on the flexoelectricity, especially the flexoelectricity in solid materials in macroscales more valuable. It has great significance in researching the flexoelectricity in macro scale: the electrostatic force, the surface phenomenon, the characteristic sizes and other micro-scale influences has hardly influence on the measurement in macro scales, a more real flexoelectric response will be experimentally obtained. This research could also help the development of the flexoelectric based theory, and accomplish some basic works on the future study of the experiment research in micro scales. This research will doubtlessly help the research of the applications based on the flexoelectricity. In this work, the contents contain 4 parts as below: one is the introduction and significance of the flexoelectricity in solid materials in macro scales; the second is the experimental methods on the flexoelectricity; and the coefficients measurements; the last part is the application and the potential development directions.
引文