激光干涉法测量压电材料纵向应变常数的研究

发布时间：2018-04-17 11:55

本文选题：压电材料 + 纵向应变常数d_(33)　；参考：《北京化工大学》2015年硕士论文

【摘要】：压电材料是一种能够实现电能与机械能相互转化,具有压电效应的功能性材料,被广泛应用于无损检测、通讯技术、生物医疗、军事科技等领域。压电材料质量的好坏直接决定了系统能量转换的性能,评价压电材料质量的特征参数包括纵向应变常数、介电常数、机电耦合系数、机械品质因数等,其中纵向应变常数d33是关键性指标之一,它不仅描述了压电材料换能效率的高低,还反映出弹性性质与介电性质之间的耦合关系。因此,准确测量压电材料的纵向应变常数d33尤为重要。压电材料纵向应变常数d33的测量方法分为接触式测量和非接触式测量。接触式测量不仅会破坏材料表面,还会降低测量精度。激光干涉法作为非接触式测量的一种,以其非接触、可溯源性、高精度等优点,被广泛应用于微小动态位移的测量。本文针对现有接触式测量仪器精度较低的现状,拟通过研究激光干涉法测量压电材料纵向应变常数的影响因素和不确定度评估,探讨建立压电材料纵向应变常数标准装置的可行性。在建立激光干涉法测量系统的基础上,研究了压电材料纵向应变常数d33的影响因素、测量不确定度、方法间的一致性等问题。主要工作包括：1、通过激光干涉光路的搭建、正交信号的获取、多普勒信号的解调,建立了压电材料纵向应变常数d33的激光外差干涉法测量系统。详细分析了纵向应变常数的影响因素,包括激励场强、频率、电极、温度等,并对激光干涉法测量系统进行了不确定度的评估。2、对比激光干涉法和准静态法的测量结果,从纵向应变常数d33的定义出发,分析和探讨了正、逆压电效应下纵向应变常数d33之间的一致性以及差异原因。3、研究结果表明,在远离谐振频率点以下,纵向应变常数d33随着激励频率的增加基本保持不变；在激励场强远小于极化场强时,硬质压电陶瓷纵向应变常数d33不随激励场强而改变,而软质压电陶瓷纵向应变常数d33与激励场强存在线性关系；材料均匀性和极化程度的不同,以及测量时约束条件的制约,压电材料表面各处纵向应变常数d33数值往往并不相等,通常呈现中心处数值最小,边缘处数值最大；对激光外差干涉测量法不确定度评定结果表明,在10nm-150nm范围内,纵向应变常数d33测量不确定度优于2.30%；方法之间的一致性研究表明,正逆压电效应下的,激光干涉法测量结果略大于准静态法测量结果,且更接近材料真实d33值,激光干涉法可以作为一种绝对校准方法,给压电材料的纵向应变常数赋值,并用于准静态仪器的校准。
[Abstract]:Piezoelectric material is a kind of functional material which can realize the mutual conversion of electrical energy and mechanical energy and has piezoelectric effect. It is widely used in nondestructive testing, communication technology, biomedicine, military science and technology and so on.The quality of piezoelectric material directly determines the energy conversion performance of the system. The characteristic parameters for evaluating the quality of piezoelectric material include longitudinal strain constant, dielectric constant, electromechanical coupling coefficient, mechanical quality factor, etc.The longitudinal strain constant D33 is one of the key indexes. It not only describes the energy transfer efficiency of piezoelectric materials, but also reflects the coupling relationship between elastic properties and dielectric properties.Therefore, it is very important to accurately measure the longitudinal strain constant d 33 of piezoelectric materials.The measuring methods of longitudinal strain constant d 33 of piezoelectric materials can be divided into contact measurement and non-contact measurement.Contact measurement will not only destroy the surface of the material, but also reduce the measurement accuracy.As a kind of non-contact measurement, laser interferometry is widely used in the measurement of small dynamic displacement because of its advantages of non-contact, traceability and high accuracy.In view of the low precision of the existing contact measuring instruments, this paper intends to study the factors affecting the measurement of longitudinal strain constants of piezoelectric materials by laser interferometry and the evaluation of the uncertainty.The feasibility of establishing a standard device for longitudinal strain constants of piezoelectric materials is discussed.Based on the laser interferometry measurement system, the factors affecting the longitudinal strain constant d33 of piezoelectric materials, the uncertainty of measurement, and the consistency among the methods are studied.The main work includes: 1. The laser heterodyne interferometry measuring system of piezoelectric material longitudinal strain constant D33 is established by constructing the laser interference optical path obtaining the orthogonal signal and demodulating the Doppler signal.The influence factors of longitudinal strain constant, including excitation field strength, frequency, electrode, temperature and so on, are analyzed in detail. The uncertainty of laser interferometry measurement system is evaluated. The results of laser interferometry and quasi-static method are compared.Based on the definition of longitudinal strain constant D33, the consistency of longitudinal strain constant D33 and the cause of the difference under positive and inverse piezoelectric effects are analyzed and discussed. The results show that it is below the resonant frequency point.The longitudinal strain constant d33 remains basically unchanged with the increase of excitation frequency, and the longitudinal strain constant d33 of hard piezoelectric ceramics does not change with the excitation field strength when the excitation field intensity is much smaller than that of polarization field.The longitudinal strain constant D33 of soft piezoelectric ceramics is linearly related to the excitation field strength, and the values of the longitudinal strain constant d33 are not always equal due to the difference of material uniformity and polarization, and the restriction of measurement conditions.In general, the center value is the smallest and the edge value is the largest. The evaluation results of the uncertainty of the laser heterodyne interferometry show that the uncertainty of the longitudinal strain constant d33 is better than 2.30 in the 10nm-150nm range.Under the positive and inverse piezoelectric effect, the measured results by laser interferometry are slightly larger than those by quasi-static method, and are closer to the true D33 value of materials. Laser interferometry can be used as an absolute calibration method to assign the longitudinal strain constants of piezoelectric materials.And used for the calibration of quasi-static instruments.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34;TN249

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