夹心式复合变幅杆换能器频率方程的推导

应用复合变幅杆及夹心式换能器结构,研制了一种新型夹心式发射换能器。根据等效电路理论推导了这种夹心式复合变幅杆换能器的等效电路模型,得出了换能器频率方程。考虑黄铜电极片对压电振子的密度及等效纵波声速的影响,应用等效参数理论修正了频率方程。通过实验验证,误差由修正前的2.09%降低到修正后的0.64%。     

纵横耦合振动夹心式压电超声换能器的研究

本文利用解析方法研究了大尺寸及高频夹心式压电超声换能器的耦合振动。通过引入各部分的振动耦合系数及等效弹性系数，推出了换能器的基模耦合振动频率方程。与数值方法相比，由于计算公式具有简单的解析表达形式，因此无需电子计算机就可迅速得出结果。实验表明，本文理论得 出的夹心式换能器的共振频率比一维理论得出的结果更加接近于实际测量值。     

大功率夹心式压电换能器结构参数计算分析及设计

基于一维纵振理论和机电等效原理,得到了单匹配层夹心式压电换能器辐射声压级的计算公式,通过该公式对换能器结构参数对其谐振频率和辐射声压级(sound pressure level,SPL)的影响进行了计算分析。计算结果表明:换能器径向尺寸对谐振频率的影响不大,但前盖板径向尺寸的增大会提高辐射声压级;纵向尺寸的增大会使换能器系统谐振频率降低,但增加前盖板厚度,或增大前后盖板厚度比,有利于辐射声压级的提高;增加压电晶片的片数、厚度和面积都可使换能器辐射声压级提高;换能器发射端增加匹配层能有效提高辐射声压级,匹配层的厚度和密度对声压级幅值和带宽有影响。依据计算结果,进行了给定指标要求的换能器的设计计算。     

一种可用于重油降粘的大功率超声换能器设计

基于夹心式压电换能器基本原理,设计了一种可用于井口重油降粘和高凝油降凝的工业规模应用的大功率压电超声换能器,其工作频率为16.86 kHz,输入电功率为500 W,可在100℃高温环境下长时间连续工作。首先根据工作环境需要设计了换能器模型,结合等效电路法和传输矩阵法,计算了换能器满足谐振频率条件的各部分参数;通过有限元仿真软件ANSYS对换能器进行了模态分析和谐响应分析,确定了换能器的最佳工作模态和工作频率。根据仿真模型,制作了工程样机,通过阻抗分析仪测得其实际的工作频率与仿真结果的误差为0.5%。这种大功率压电超声换能器有望在重油降粘以及超声处理工业中得到规模化应用。     

VII型低频弯张稀土换能器研究

为了进一步提高VII型弯张换能器的工作性能,本文对VII型低频弯张稀土换能器课题研究作了总结:研究了弯张换能器各方向尺寸与其同相振动谐振频率之间的关系;计算了VII型弯张换能器壳体给驱动元件施加一定预应力时,壳体所需的装配位移的大小,并作了相应的实验验证;对研制出的换能器弯张壳体及换能器的振动模态进行了测试,与理论计算相符;测试了VII型弯张换能器的声学性能-水中呼吸模态对应谐振频率为1.16kHz,带宽为680Hz,机械品质因数Qm为1.71,单位电流发射响应在谐振频率处达到186.1dB,电声效率为13.1%;弯张换能器随入水深度的不同, 驱动元件两端所受到的总的预应力是不同的,计算了换能器入水深度与预应力的关系;利用赫姆霍茨积分方程—有限元结合方法,计算出了换能器辐射声场指向性。在本文最后,指出了今后改进该型换能器性能的方向。     

计及横向振动的夹心式功率超声压电换能器

研究了大尺寸夹心式压电换能器的耦合振动。通过引入各部分的振动耦合系数及等效弹性系数,推出了换能器的耦合振动频率方程。与一维理论比,本方法不受换能器横向尺寸的限制。与数值方法比、本方法无需电子计算机就可迅速得出结果。实验表明,本方法得出的夹心式换能器的共振频率比一维理论得出的结果更接近于实测值。     

压电换能器在并联谐振频率附近特性的研究

对压电换能器在并联谐振频率附近的特性包括功率自动调节性能、品质因数、效率、激励电压及承受电压等进行了分析研究。这些特性对大功率超声换能器的合理运用具有重要影响。用实验验证了分析计算的结果,并在某些方面给出了与串联谐振频率附近特性的比较。     

一种确定换能器参数的方法

一、前言 大家知道,换能器工作在谐振频率时,可以用集总参数来表示换能器等效线路中的各元件。这对于分析换能器在谐振点的性能是有用的。但仅仅知道谐振点的等效线路是不够的。如果能够在谐振频率以外的其他频率也用等效线路的方法来描述换能器,这对于分析换能器和换能器阵的性能是很有用的。这样做的前提是承认等效线路的各参数是频率的函数,并且能够确定在各个频率下的等效线路的参数。知道了不同频率下各参数的值,就可分析和计算换能器的带宽,不同频率工作时的效率,换能器的相位变化、互辐射阻抗的大小和随频率的变化、互辐射对换能器和…     

Ⅶ型低频弯张稀土换能器研究

为了进一步提高Ⅶ型弯张换能器的工作性能，本文对Ⅶ型低频弯张稀土换能器课题研究作了总结：研究了弯张换能器各方向尺寸与其同相振动谐振频率之间的关系；计算了Ⅶ型弯张换能器壳体给驱动元件施加一定预应力时，壳体所需的装配位移的大小，并作了相应的实验验证；对研制出的换能器弯张壳体及换能器的振动模态进行了测试，与理论计算相符：测试了Ⅶ型弯张换能器的声学性能．水中呼吸模态对应谐振频率为1．16kHz,带宽为680Hz，机械品质因数Qm为1．71，单位电流发射响应在谐振频率处达到186．1dB，电声效率为13．1％；弯张换能器随入水深度的不同，驱动元件两端所受到的总的预应力是不同的，计算了换能器入水深度与预应力的关系；利用赫姆霍茨积分方程一有限元结合方法，计算出了换能器辐射声场指向性。在本文最后，指出了今后改进该型换能器性能的方向。     

压电-磁致伸缩双层磁电复合材料的机电谐振

基于压电相和磁致伸缩相的本构方程以及弹性体的运动方程,简要推导了一维机电谐振模式下压电-磁致伸缩双层磁电复合材料横向磁电电压系数的表达式。采用相应的材料参数计算分析了Tb_1-x Dy_x Fe_2-y (TDF)-Pb(Zr,Ti)O₃(PZT)双层磁电复合材料的横向磁电电压系数与交流磁场频率的关系,以及复合材料的长度和压电相体积分数对机电谐振频率的影响。计算与分析结果表明,双层磁电复合材料在机电谐振频率处具有明显的磁电 响应特性。当有效机械品质因数为50,在谐振频率55.2 kHz处横向磁电电压系数达到峰值11.2 V·cm^-1·Oe^-1,是低频下峰值(281.9 mV·cm^-1·Oe^-1)的40倍。机电谐振频率随复合材料长度的减小和压电相体积分数的增加而上升。实验结果说明TDF-PZT双层磁电复合材料在机电谐振频率处具有显著增强的磁电效应,实际有效机械品质因数约为48。     

Radially composite piezoelectric ceramic tubular transducer in radial vibration

The radially composite piezoelectric tubular transducer is studied. It is composed of radially poled piezoelectric and a long metal tube. The electro-mechanical equivalent circuit of the radially poled piezoelectric and metal tube in radial vibration is obtained. Based on the force and velocity boundary conditions, the six-port electro-mechanical equivalent circuit for the composite tubular transducer is given and the resonance/anti-resonance frequency equations are obtained. The relationship between the resonance frequency and the dimensions is analyzed. Numerically simulated results obtained by the finite element method are compared with those from the analytical method. Composite piezoelectric tubular transducers are designed and manufactured. The resonance/anti-resonance frequencies are measured, and it is shown that the theoretical results are in good agreement with the simulated and experimental results. It is expected that radially composite piezoelectric tubular transducers can be used as high-power ultrasonic radiators in ultrasonic applications, such as ultrasonic liquid processing.     

Study on a new type of radial composite piezoelectric ultrasonic transducers in radial vibration

In this paper, a new type of radial composite ultrasonic transducers in radial vibration is presented and studied. The radial composite ultrasonic transducer consists of a solid piezoelectric ceramic thin disk and a hollow metal thin, circular ring in radial vibration; and they are connected together in the radial direction. The radial vibrations of a piezoelectric ceramic thin disk and a hollow, metal, thin, circular ring are analyzed, respectively. Their radial electromechanical equivalent circuits are obtained. Based on the electromechanical equivalent circuits and using the boundary conditions between the piezoelectric ceramic thin disk and the hollow, metal, thin ring, the electromechanical equivalent circuit of the radial composite ultrasonic transducer is derived and the resonance frequency equation is obtained. The theoretical results from the resonance frequency equation are in good agreement with the measured radial resonance frequencies, and they also are in a good agreement with the results from the numerical method.     

Radial vibration of the composite ultrasonic transducer of piezoelectric and metal rings

The radial composite ultrasonic transducer of a piezoelectric ceramic ring and a metal ring is studied. The radial vibrations of a piezoelectric ceramic ring polarized in the thickness direction and a metal ring are analyzed and their electromechanical equivalent circuits are obtained. On the basis of the electromechanical equivalent circuits of the piezoelectric and the metal ring and the radial boundary conditions, the total electromechanical equivalent circuit for the composite ultrasonic transducer is also obtained. The resonance frequency and anti-resonance frequency equations of the composite ultrasonic transducer are given. Some radial composite ultrasonic transducers are designed and manufactured and their resonance and anti-resonance frequencies are measured. Experiments show that the measured resonance frequencies are in a good agreement with the theoretical results.     

A3夹心式压电超声扭转换能器的研制

本文对夹心式压电超声扭转振动换能器进行了理论及实验研究，得出了对称型扭转振动夹心换能器的共振频率设计方程，给出了频率方程式中一些主要的物理量的具体表达式。在此基础上，实际设计并制作了一个夹心扭转振动换能器，并对其所有的电声参数进行了测试     

Radiation impedance and equivalent circuit for piezoelectric ultrasonic composite transducers of vibrational mode-conversion

The piezoelectric ultrasonic composite transducer, which can be used in either gas or liquid media, is studied in this paper. The composite transducer is composed of a longitudinal sandwich piezoelectric transducer, a mechanical transformer, and a metal circular plate in flexural vibration. Acoustic radiation is produced by the flexural circular plate, which is excited by the longitudinal sandwich transducer and transformer. Based on the classic flexural theory of plates, the equivalent lumped parameters for a plate in axially symmetric flexural vibration with free boundary conditions are obtained. The radiation impedance of the plate is derived and the relationship between the radiation impedance and the frequency is analyzed. The equivalent circuits for the plate in flexural vibration and the composite transducer are given. The vibrational modes and the harmonic response of the composite piezoelectric transducer are simulated by the numerical method. Based on the theoretical and numerical analysis, two composite piezoelectric ultrasonic transducers are designed and manufactured, their admittance-frequency curves are measured, and the resonance frequency is obtained. The flexural vibrational displacement distribution of the transducer is measured with a laser scanning vibrometer. It is shown that the theoretical results are in good agreement with the measured resonance frequency and the displacement distribution.     

扭转振动压电超声换能器的研究

用声强技术检测区分板壳结构的空气传声与结构传声时，结构的辐射效率之差决定了检测结果的可信度，文中分析了实际结构的在声场激励下的实测辐射效率与无限大结构的空气传声辐射效率之差，及对区检测结果的影响。实验结果证实了理论分析。     

扭转振动压电超声换能器的研究

本文对夹心式复合结构压电超声扭转振动换能器进行了系统的理论研究，该换能器由两段金属真圆棒及切向极化的压电陶瓷圆片堆复合而成，文中首先研究了切向极化压电陶瓷细长管的扭转振动性，推出了其机电等效电路，并提出了压电陶瓷细长管截面扭转系数的概念。，     

Sandwiched piezoelectric ultrasonic transducers oflongitudinal-torsional compound vibrational modes

Sandwiched piezoelectric ultrasonic transducers of longitudinal-torsional compound vibrational modes were studied. The transducers consist of coaxially segmented, longitudinally and tangentially polarized piezoelectric ceramic rings, a back metal cylinder, and a front exponential solid metal horn. Based on the plane-wave approximation, the equivalent circuits of the longitudinal and torsional vibrations in the sandwiched transducer were obtained and the resonance frequency equations of the transducer in longitudinal and torsional vibrations were derived. By means of choosing the radius decay coefficient of the front exponential horn, the longitudinal and torsional vibrations are made to resonate at the same frequency in the transducer. Sandwiched piezoelectric ultrasonic transducers of longitudinal-torsional compound modes were designed and fabricated according to the frequency equations. It is demonstrated that the measured resonance frequencies of the transducers are in good agreement with the theoretical results, and the measured resonance frequencies of the transducers in longitudinal and torsional vibration modes are also in good agreement with each other. Theoretical and experimental results show that this kind of transducer can be used in ultrasonic welding, ultrasonic machining, ultrasonic motors, and other ultrasonic applications which need large displacement amplitudes     

超声珩齿中弯曲振动变幅器的设计与研究

齿轮是超声珩齿加工中的一类特殊负载,它的振动特性和固有频率对系统的加工频率影响很大.由于齿轮的尺寸和质量大,且其尺寸不能任意更改,现有的振动系统设计理论,如全谐振设计理论、质量置换理论、局部共振理论等,都不能适用于这一情况.为解决此问题,应用Mindlin中厚板理论、变幅杆设计原理和机械阻抗理论对由变幅杆、齿轮组成的变...     

Piezoelectric ceramic rectangular transducers in flexural vibration

Based on the equivalent elastic method and coupled vibration theory, an analytic method is presented to study the flexural vibration of rectangular transducers consisting of piezoelectric ceramic thin plates. By introducing a mechanical coupling coefficient, the flexural vibration of the piezoelectric ceramic rectangular thin plate is reduced to two simple, one-dimensional flexural vibrations of narrow piezoelectric ceramic strips. The resonance frequency equations for the piezoelectric ceramic rectangular thin-plate transducers in flexural vibration are derived under the free and simply supported boundary conditions analytically. The relationship between the resonance frequency and the flexural vibrational order, the geometrical shape, and the dimensions of the piezoelectric ceramic rectangular thin-plate transducer is analyzed. It is demonstrated that the one-dimensional vibrational theory for the flexural vibration of a narrow piezoelectric ceramic strip and the stripe-mode flexural vibrational theory for the piezoelectric ceramic rectangular thin plate can be derived directly from the theory obtained in this paper. Experimental results show that the measured resonance frequencies of the piezoelectric ceramic rectangular thin-plate transducers in flexural vibration under free-boundary conditions are in good agreement with the calculated results. The method presented in this paper can be used in the resonance frequency analysis of vibrating systems in coupled vibration.