径向夹心式压电超声换能器的研究

发布时间：2018-06-09 05:37

本文选题：径向极化 + 径向振动　；参考：《陕西师范大学》2015年博士论文

【摘要】：在超声清洗、超声处理等功率超声的应用中,换能器是以实现向介质辐射大功率声能为目的。通常功率超声换能器大都采用结构简单、机电耦合系数及机电转换效率高、且易于优化设计的纵向振动形式的夹心式压电陶瓷超声换能器。但传统的纵向振动夹心式换能器由于横向尺寸要小于辐射声波波长的四分之一,因此,换能器的声波辐射面积受到限制；另外,此类换能器的辐射射能量基本上是沿着换能器的纵轴方向辐射,不能实现超声能量的空间辐射,这使得超声波作用范围受到了限制；还有传统换能器的共振频率单一难以调整,不能满足某些应用场合的需要。因此,基于以上原因,为了适应功率超声新技术的要求,克服传统换能器存在的一些弊端,本文提出了一种新型结构的换能器,该换能器由径向极化的压电陶瓷圆管和内外金属圆管在径向复合而成。该换能器结构简单,对传统换能器是一种创新,对于发展新型的超声换能器、改善现有超声技术的应用效果、开发新的超声技术及应用领域具有理论指导意义和实际应用价值。本文主要对以下几方面进行研究：(1)金属管作为超声换能器振动系统的重要组成部分,对其径向振动特性进行了研究。从管长与半径关系将其分为三类来进行研究,分别是纵向尺寸远小于径向尺寸的薄圆盘圆环、纵向尺寸远大于径向尺寸的金属长圆管以及纵径尺寸接近的金属圆柱、圆管。从平面应力问题出发,推导出金属薄圆盘、圆环径向振动的机电等效电路,得到其径向振动频率方程,由此得到径向尺寸与径向共振频率间的相互关系。通过ANSYS有限元模拟仿真表明理论计算与数值仿真是一致的。从平面应变问题出发,推导出金属长圆管径向振动的机电等效电路,得到其径向振动频率方程,由此得到尺寸与径向共振频率间的相互关系。通过ANSYS有限元模拟仿真表明理论计算与数值仿真是一致的,通过数值仿真说明薄壁金属长圆管辐射器在径向有较强的辐射声场。采用表观弹性法来分析纵径尺寸接近的实心、空心圆柱,将实心、空心圆柱的耦合振动等效为两个一维振动,它们通过机械耦合系数相互作用。通过分析可知圆柱耦合振动的机电等效电路由细棒纵向振动和薄圆盘或圆环径向振动等效电路构成。并据此得到各自纵向、径向振动的频率方程。获得在纵向与径向产生强烈耦合振动的条件。有限元数值模拟了圆柱的振动特性,模拟结果与实验结果相吻合。(2)径向极化的压电陶瓷管作为径向夹心式超声换能器的激励单元,对其径向振动特性进行了研究。依据压电管纵径尺寸间的关系,对压电短圆管、长压电管以及纵径尺寸接近的压电管分别对其分析。从平面应力问题出发,推导出径向极化压电短圆管径向振动的机电等效电路,从而得到其共振和反共振频率方程。由此得到几何尺寸与共振频率、反共振频率以及有效机电耦合系数间的相互关系,最后用ANSYS有限元软件数值仿真,结果与理论计算一致,说明理论的正确性。从平面应变问题出发,用相似于压电短圆管的方法,推导压电陶瓷长圆管径向振动的机电等效电路,得到其共振和反共振频率方程。得到几何尺寸与共振频率、反共振频率以及有效机电耦合系数间的相互关系,并用ANSYS有限元软件数值仿真,结果与理论计算一致,说明理论的正确性。采用表观弹性法研究纵径尺寸接近的压电管,将其耦合振动等效为纵向和径向振动,得到各自的机电等效电路和频率方程。有限元数值模拟了圆柱的振动特性,模拟结果与实验结果相吻合。(3)提出一种新型结构的径向夹心式超声换能器,按纵径尺寸关系,分别对径向夹心式短管换能器、径向夹心式长圆管换能器以及耦合振动的径向夹心式换能器进行分析。将换能器各组成部分在径向相连,得到各换能器的机电等效电路,从而推导出各自共振与反共振频率方程,由此得到几何尺寸与共振、反共振频率以及有效机电耦合系数间的关系。设计、加工了三种径向夹心式换能器,理论计算、数值仿真、实验测试结果比较一致。对各种换能器在水中的辐射声场进行了模拟仿真,仿真表明短管、长圆管换能器在液体中做径向辐射,且在水中具有管内声场聚焦作用。纵径尺寸接近的径向夹心换能器可在径向与纵向全方位的辐射,并且电压发射响应带宽也较宽。该类换能器可应用于功率超声,如超声液体处理、声化学、超声萃取等。
[Abstract]:In the application of ultrasonic cleaning, ultrasonic processing and other power ultrasonic applications, the transducer is designed to achieve high power sound energy radiation to the medium. Usually, the ultrasonic transducer of the piezoelectric ceramic transducer is mostly used for the piezoelectric ceramic ultrasonic transducer with simple structure, the electromechanical coupling coefficient and the high efficiency of electromechanical conversion, and it is easy to optimize the design of the longitudinal vibration mode. The traditional longitudinal vibration sandwich transducer is less than 1/4 of the wavelength of the radiation sound wave. Therefore, the acoustic radiation area of the transducer is limited. In addition, the radiation energy of the transducer is basically radiated along the longitudinal axis of the transducer, and the space radiation of the ultrasonic energy can not be realized, which makes the ultrasonic wave. The range of action is limited, and the resonant frequency of the traditional transducer is difficult to adjust to meet the needs of some applications. Therefore, based on the above reasons, in order to adapt to the requirements of the new power ultrasonic technology and overcome the disadvantages of the traditional transducer, a new type of transducer is proposed in this paper. The radial polarized piezoceramic circular tube and the inner and outer metal tube are combined in radial direction. The structure of the transducer is simple, and it is an innovation for the traditional transducer. It has theoretical guiding significance and practical application value for developing new ultrasonic transducer, improving the application effect of the existing ultrasonic technology and developing new ultrasonic technology and application fields. This paper mainly studies the following aspects: (1) as an important part of the vibration system of an ultrasonic transducer, the metal tube is a part of the vibration system of the ultrasonic transducer, and its radial vibration characteristics are studied. It is divided into three types from the relationship between the length and the radius of the tube, and the longitudinal size is far smaller than the radial size, and the longitudinal size is far larger than the radial. A metal circular tube of size and a metal cylinder and a circular tube with close longitudinal dimensions. Based on the plane stress problem, an electromechanical equivalent circuit of a thin metal disk and a radial vibration is derived. The radial vibration frequency equation is obtained. The relationship between the radial vibration frequency and the radial resonance frequency is obtained. The simulation table is simulated by the ANSYS finite element method. The theoretical calculation is consistent with the numerical simulation. Based on the plane strain problem, the electromechanical equivalent circuit of the radial vibration of the metal long circular tube is derived, and the radial vibration frequency equation is obtained. Thus the relationship between the size and the radial resonance frequency is obtained. The simulation results of the ANSYS finite element simulation show that the theoretical calculation is in agreement with the numerical simulation. The numerical simulation shows that the radiant field of the thin-walled tube radiator is stronger in the radial direction. Using the epigenetic elastic method to analyze the solid, hollow cylinder, the coupling vibration of solid and hollow cylinders is equivalent to two one-dimensional vibrations, and they interact through the mechanical coupling coefficient. Through analysis, the cylindrical coupling is known. The electromechanical equivalent circuit of the vibration is composed of the longitudinal vibration of a fine rod and the equivalent circuit of the radial vibration of a thin disk or a circular ring. The frequency equations of the longitudinal and radial vibration are obtained accordingly. The conditions of strong coupling vibration are obtained in the longitudinal and radial directions. The finite element numerical simulation is used to simulate the vibration characteristics of the cylinder, and the simulation results are in agreement with the experimental results. (2 The radial polarization piezoelectric ceramic tube is used as the excitation unit of the radial sandwich transducer, and its radial vibration characteristics are studied. According to the relationship between the longitudinal diameter and size of the piezoelectric tube, the piezoelectric short circular tube, the long pressure tube and the piezoelectric tube near the longitudinal diameter are separately analyzed. The radial polarization is derived from the plane stress problem. The electro-mechanical equivalent circuit of the radial vibration of the piezoelectric short circular tube is obtained, and the resonance frequency and the anti resonance frequency equation are obtained. The relationship between the geometric size and resonance frequency, the resonance frequency and the effective electromechanical coupling coefficient is obtained. Finally, the numerical simulation of the ANSYS finite element software is used to agree with the theoretical calculation, indicating the correctness of the theory. Based on the plane strain problem, the electromechanical equivalent circuit of the radial vibration of the piezoceramic long circular tube is derived by using the method similar to the piezoelectric short circular tube. The resonance and anti resonance frequency equations are obtained. The relationship between the geometric size and the resonance frequency, the resonance frequency and the effective electromechanical coupling coefficient are obtained, and the numerical simulation of the ANSYS finite element software is used. The results are in agreement with the theoretical calculation, indicating the correctness of the theory. The piezoelectric tubes with close longitudinal dimensions are studied by the epigenetic elastic method, and their coupling vibration is equivalent to the longitudinal and radial vibration, and their respective electromechanical equivalent circuits and frequency equations are obtained. The finite element numerical simulation is used to simulate the vibration characteristics of the cylinder. The simulation results are in agreement with the experimental results. (3) (3) A new type of radial sandwich transducer is used to analyze the radial sandwich type short tube transducer, radial sandwich type long circular tube transducer and coupling vibration radial sandwich transducer respectively. The electromechanical equivalent circuit of each transducer is obtained by connecting the components of the transducer in the radial direction. The relations between the geometric size and resonance, the resonance frequency and the effective electromechanical coupling coefficient are derived. Three radial sandwich transducers are designed, the theoretical calculation, the numerical simulation and the experimental results are consistent. The radiation sound field of various transducers in the water is simulated. The simulation shows that the short tube, the long circular tube transducer is radially radiating in the liquid and has the focus of the sound field in the water. The radial sandwich transducer with close longitudinal diameter can be radially and longitudinally radiated, and the voltage emission response bandwidth is wide. The transducer can be applied to power ultrasonic, such as ultrasonic liquid treatment. Sonochemistry, ultrasonic extraction and so on.
【学位授予单位】：陕西师范大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB552

【参考文献】