切向极化压电陶瓷细长圆棒的扭转振动研究

利用压电材料的压电及运动方程，本文研究了切向极化压电陶瓷细长棒的扭转振动，分析了扭转振动压电陶瓷细棒中扭转角及扭矩的分布规律，推出了扭转振动压电陶瓷振子的机电等效电路，并得出了振子的共振及反共振频率方程，为扭转振动超声换能器的设计及计算奠定了一定的理论基础。     

用于超声清洗复合振动换能器的研究

本文研究了一种由纵向振动夹心式压电超声换能器与弯曲圆盘组成的用于液体中超声处理的复合振动辐射器。推出了恢复合振动系统的共振频率设计方程，分析了各个振动模式的机电转换特性及其声波辐射特性，测量了振动系统的共振频率及其有效机电耦合系数。从实验及理论结果可以看出，振动系统的频率测试值与设计值基本符合。在一定的共振频率上，该振动系统具有最大的有效机电耦合系数，是一种很有前途的功率超声辐射器。     

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。，     

阶梯型径向振动环形变幅器的振动特性

文中首先对各向同性弹性薄圆环的径向振动进行了研究,得出了其等效电路。在此基础上,对由双金属圆环组成的阶梯型径向振动变幅器进行了探讨,推出了其径向振动的复合等效电路及其共振频率方程。分析了此类径向振动变幅器的共振频率及径向位移振幅放大系数与其几何尺寸之间的依赖关系。利用数值方法,对变幅器的径向振动特性进行了数值模拟,结果表明,数值结果与解析结果符合很好。     

锥盘形超声聚能器的耦合振动特性与优化设计

超声聚能器具有放大振幅、匹配声阻抗、提高声能量传输效率的作用,盘形聚能器与压电圆管组合能够扩大声能量的辐射范围。采用传统的一维理论对盘形聚能器振动的分析,往往忽略了高度对振动的影响。为了获得符合盘形聚能器实际振动的解析理论,以结构简单且易加工的锥盘形超声聚能器为研究对象,利用等效弹性法分析了高度与半径尺寸接近的聚能器的径、纵向耦合振动。通过引入机械耦合系数,推导得到了聚能器耦合振动的机电等效电路、共振频率方程组和径向位移放大倍数。进一步分析了聚能器机械耦合系数、共振频率和径向位移放大倍数与几何尺寸的依赖关系。利用有限元法对聚能器的耦合振动模态进行了仿真,理论计算与模拟结果一致,验证了理论推导的正确性。振动特性与优化结论的获得为盘形聚能器的工程应用提供了理论依据,为径向复合换能器的振动分析奠定了研究基础。     

三叠片压电复合换能器弯曲振动的比较研究

用瑞利法对三叠片弯振圆盘换能器在三种不同边界条件下的振动特性进行理论研究,推导了谐振频率及有效机电耦合系数的表达式,通过数值计算分析了复合换能器的谐振频率及有效机电耦合系数随换能器各结构参数的变化规律并进行比较研究,同时将计算结果与有限元模拟结果比较,结果表明不同边界条件下换能器的结构参数对谐振频率和有效机电耦合系数影响不同:在换能器结构参数一定时,自由边界条件下谐振频率最大,简支边界条件下最小,固定边界条件下次之;有效机电耦合系数随着金属片厚度、陶瓷片厚度和陶瓷片半径变化时,分别有一个最大值;其他参数一定时,有效机电耦合系数在简支边界条件下最大,自由边界条件下的值稍大于固定边界条件下的值。上述研究结果可为三叠片弯曲振动换能器的设计和实际应用提供一定的理论支持。     

考虑压电效应时压电陶瓷圆形振子的耦合振动

在考虑压电效应的情况下，本文对压电陶瓷圆形振子的耦合振动进行了研究。根据压电陶瓷圆形振子的运动方程及压电方程，通过引入振子不同振动模式之间的机械耦合系数，分析了振子轴向及径向振动之间的耦合关系，得出了振子耦合振动的电导纳表达式，并导出了共振频率方程。与一维理论的结果相比，由本文理论得出的振子共振频率与实际测量值更加符合。     

压电复合材料换能器耦合振动特性研究

本文建立了针对压电复合材料的压电复合换能器耦合振动有限元模型,采用有限元方法研究了压电复合材料类型对换能器振动模态与共振频率的影响,并对换能器共振频率与压电复合材料结构几何尺寸之间的关系进行研究。结果表明:压电复合材料类型不同,换能器的振动模态振型会发生改变,并且其前两阶共振频率差值会因压电复合材料的基体材料的杨氏模量和泊松比的不同而发生变化,即共振频率差值随着基体材料杨氏模量的增大而增大,但随着泊松比的增大而减小;而且共振频率与压电复合材料的结构几何尺寸有关,即随着压电复合材料厚度的增大,换能器的纵向振动频率与弯曲振动频率都会逐渐减少,但两频率之间的间距是逐渐拉大的。     

压电圆环晶片堆的径向振动分析

通过理论分析、数值计算、实验测量研究压电圆环晶片堆的径向振动,应用压电本构方程,通过求解晶片堆的导纳,取其最大,推导压电圆环晶片堆的共振频率方程。采用数值法对理论方程进行模拟计算,用阻抗测量和激光扫描測振实验测量单片圆环和晶片堆的共振频率,并与理论计算进行比较,结果吻合较好,误差小于1.5%。     

纵-弯复合系统的振动特性研究

本文对一种常用的纵－弯复合振动系统进行了研究，该系统由一个弯曲振动工具头及一个纵振动驱动系统组成，文中对复合振动系统的振动特性进行了理论及实验研究，推出了系统的共振及反共振频率方程，还导出了复合振动系统的机械输入阻抗，并对系统的共振频率随长度的变化规律进行了探讨，实验表明，复合振动系统共振频率的测试值与计算值符合较好，系统的共振频率随振动系统几何尺寸的变化而变化，并且，弯曲振动系统的尺寸变化对频率     

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.     

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.     

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。     

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     

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.     

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.     

压电陶瓷振子中的损耗及其对振子特性的影响

压电振子的等效电路形式当考虑损耗时可用两种方法表示：一种方法是不改变相应无损振子的等效电路形式,而将电路参数取为复数;另一种方法是在电路中加入耗能元件。文中分析了压电材料中的损耗现象,并用复数表示有损耗压电振子的各种参数。从压电振子的阻抗方程出发,详细分析了纵效应劝及横效应振动模式振子的谐振频率、频率偏移量与损耗大小、机电耦合系数大小的关系。