【作者】 马玉婷；

【导师】 冯志华；

【作者基本信息】 中国科学技术大学 ， 精密仪器及机械， 2011， 博士

【摘要】 压电复合材料是上世纪七十年代发展起来的一种新型材料,它不仅具有压电陶瓷的响应速度快、可控精度高、低能耗、无电磁干扰等优点,同时具有良好的柔韧性和机械加工性能,克服了压电陶瓷易碎和难以加工成复杂形状的缺点,易于与水及生物组织实现声阻抗匹配,已广泛应用于水声换能器和医疗超声成像等领域。其中1-3型压电复合材料具有优良的特性,且易于制备,是复合材料中研究和应用最为广泛的一种。传统的1-3型压电复合材料使用方形或者圆柱形立柱与基体材料复合,本文使用压电陶瓷管与基质复合,制成压电管式复合驱动器以适应于多种场合的应用。除了具有传统压电复合物的优点之外,压电管式复合物所需的极化和驱动电压低,能够与导体基质复合,每个压电陶瓷管可以独立控制,电场利用率高,易于完成多模式驱动。基于短管的片状复合物可以应用在超声波和高频振动抑制方面。基于长管的片状或者块状复合物可以用在所需位移较大的场合,例如形状控制,中低频的振动和噪声控制,变形镜和压电马达等。本文以压电管式复合驱动器为研究对象,首先利用经典理论和有限元法系统的研究了压电管式复合物的静、动态特性,其次分析了四管单元复合物在特定驱动模式下的静态和谐振特性,最后列举了压电管式复合驱动器在弯曲摇头式压电马达以及新型压电离心泵中的应用实例。主要工作及结论包括:结合电场分布模型,分析了压电单管的静、动态特性。将压电应变类比于热应变,用rule of the mixture models和concentric cylinder models进行压电管式复合物的宏观等效性能参数计算公式的推导。研究了电场的非均匀性对其压电系数产生的影响,给出了密度、介电常数、压电常数以及弹性模量的计算公式,讨论了不同压电陶瓷管体积分数、厚径比、分布密度以及基体材料对复合物压电特性产生的影响。借助有限元软件对复合物单元的压电系数和杨氏模量矩阵进行推导,研究了陶瓷材料的体积分数对其产生的影响,并与理论结果对比。仿真了复合物单元在不同载荷下容易引发材料破坏的应力分布情况。分析了复合物的振动模态及其共振频率随结构尺寸参数的变化趋势。对各管独立驱动的四管复合驱动器进行了研究。理论分析了其静态与动态特性,给出了弯曲挠度、力矩及其共振模态参数的计算公式。与传统薄壁理论进行对比,证实了分析的合理性。制作了四管复合驱动器样机并进行性能测试,结合有限元分析验证了理论推导的正确性。并将四管复合驱动器和传统的单管四分电极驱动器在各项性能参数上做了详细的对比,证实当四管复合驱动器和单管四分电极驱动器拥有相同尺寸,在相同电场强度驱动下,四管复合驱动器的整体性能通常优于单管四分电极驱动器。此外,四管复合驱动器具有可扩展性强,电磁辐射小和驱动电压低等优点,并且可以避免传统单管四分电极驱动器制造中非对称的缺陷,提高驱动精度。它可以代替传统的单管四分电极驱动器,在扫描探针显微镜、压电马达和压电陀螺等领域有着广泛的应用价值。使用压电八管复合驱动器研制了弯曲摇头式压电马达,理论分析了八管复合驱动器的静态和动态特性。设计制作了马达样机。样机测试结果与理论值基本吻合。马达转速与驱动电压幅值呈良好的线性关系。静态时,马达定子的端部轨迹并非理想的圆,主要由压电迟滞造成。马达工作在共振频率附近,当驱动电压幅值为200V_p-p,频率为5.0kHz时,该马达的最大空载转速和堵转力矩分别为319rpm和1.6mNm。当驱动电压幅值为160V_p-p,频率为5.0kHz,预压力为0.3N时,马达的最大效率为12%,最大输出功率为7mW。设计了基于压电四管复合驱动器的新型离心式压电陶瓷泵。该泵无机械部件所以具有较高的效率;无精密阀门或者细微管道所以对液体纯净度要求不高;可扩展性强,由于压电管式复合物单个压电元件的控制独立性,可以采用不同的驱动方式衍生出多种结构。对离心泵的静、动态特性进行了理论分析。研究了静态端部弯曲挠度、输出力矩、共振模态以及液体流速对共振频率的影响。制作了原理样机并进行性能测试,实验证明该压电泵可在驱动电压幅值为120V_p-p,谐振频率232Hz时,2.0kPa的负压下以7.7ml/min的速度抽出蒸馏水。在驱动信号幅值为120V_p-p,频率为233.2Hz时,流速最大值为8.6ml/min,泵所能承受的背压最大值为5.4kPa。基于以上研究,本论文在以下方面具有创新之处:（1）对压电管式复合物的压电系数和杨氏模量矩阵进行了系统的分析,并讨论了其在不同载荷下的应力和电势分布情况。（2）利用压电四管复合物制作的驱动器的特性优于传统的单管四分电极驱动器,可以代替其在扫描隧道显微镜中发挥重要作用。（3）研制了基于压电八管复合驱动器的弯曲摇头式压电马达,其输出力矩性能优于基于单管的压电马达。（4）设计了基于压电四管复合驱动器的新型离心式压电陶瓷泵,它具有结构简单,控制方便,输出稳定和高频运作等特点。研究所取得的成果对压电管式复合物的优化设计、驱动器性能的系统分析及压电驱动技术的应用探索等方面具有一定的理论价值和实用意义。更多还原

【Abstract】 Piezoelectric composites are new type of transducer components developed in1970, which not only have the merits of piezoelectric ceramics, such as fast response,high precision, low power consumption, no electromagnetic interference, etc, but alsohavemeritsofhighflexibilityandgoodmechanicalprocessingproperties. Itovercomestheshortcomingsofpiezoelectricceramicsforbeingfragileandbeingdifficulttobefab-ricated into complex shapes. It is also easy to achieve impedance matching between thepiezoelectric composites and water or biological tissues. Piezoelectric composites havebeen widely used in acoustic transducers and medical ultrasonic imaging area. Amongthem, 1-3piezoelectriccompositesareextensivelyresearchedbecauseoftheirexcellentultrasonic character and easy fabrication process.The traditional 1-3 piezoelectric composites usually mix piezoelectric square orcylindrical columns with matrix. This paper uses piezoelectric tubes as the piezoelec-tric components to adapt to various applications. In addition to owning the merits oftraditional piezoelectric composites, the piezoelectric tubular composites require lowpoling and driving voltages and can be mixed with conductive matrix. Each piezoelec-tric tube can be controlled independently so it is easy for them to complete multi-modemotion. It utilizes electric field more efficiently than composites with interdigitatedelectrodes. Sheet shaped composites with short tubes can be applied to ultrasound andhigh-frequency vibration suppression. Sheet or block shaped composites based on longtubes can be used in occasions that require large displacement, such as shape control,medium and low frequency vibration and noise control, deformable mirrors and piezo-electric motors.Piezoelectric tubular composite actuators are studied in this paper. Firstly, the-oretical and FEM analysis on static and dynamic character of the composite actuatorare conducted in detail, followed by static and dynamic analysis on the four tubularcomposites in a particular driving mode. And a two phase traveling wave motor and apiezoelectric centrifugal pump are presented to illustrate the application of the piezo-electric tubular composite actuators. The main work and conclusions are as following:By use of electric field distribution model, the static and dynamic properties ofa single tube piezoelectric actuator were studied. By taking the piezoelectric strainas the thermal strain, the formulas of property parameters of the piezoelectric tubularcomposite were deduced with the rule of mixture models and the concentric cylinder models. The influence of non-uniform electric field on the piezoelectric coefficientswere studied. The formulas of density, dielectric constant, piezoelectric constants andYoung’s modulus were given. The piezoelectric constants as functions of volumes frac-tion, aspect ratio, distribution density of the piezoelectric tubes and matrix materialswere discovered. By means of finite element software, piezoelectric coefficients andYoung’s modulus matrix of the composite unit were derived and their change with thevolume fraction of ceramic materials were studied. Their values were compared withthe theoretical results. The stress, which is apt to cause damage to the composite, wassimulated under different loads. The vibration modes of the composite and the changeof its resonant frequencies with size parameters were analyzed.Under the condition that each piezoelectric tube is driven independently, a fourtubular composite actuator was invstigated. Theoretical analysis on its static and dy-namic character were conducted and formulas of bending deflection, output torque, andresonance frequencies were given. Compared with the traditional thin-wall theory, theanalysis in the paper is confirmed more reasonable. A prototype was fabricated andtested. By use of finite element analysis with ANSYS, theoretical analysis results wereverified. The character of the four tubular composite actuator was compared with theconventional single-tube actuator with quartered electrodes. It is confirmed that whenthetwokindsofactuatorsareinthesamesizeanddrivenbythesameelectricfieldinten-sity, four tubular composites actuator usually has better performance. In addition, fourtubular composites actuator have the advantages of large scalability, small electromag-netic radiation and low driving voltage. It is possible for tubular composite actuator tohandle with the defects of asymmetric structure of the piezoelectric tube in fabrication,which is an unconquerable problem in single-tube actuator, thus improving the drivingaccuracy. The tubular composite actuator can replace the conventional single-tube ac-tuator with quartered electrodes and work in scanning probe microscopes, piezoelectricmotors, piezoelectric gyroscopes, and even more extensive applications.A two phase traveling wave piezoelectric motor based on eight tubular compositeactuatorwasinvestigated. Theoreticalanalysisonthestaticanddynamiccharacteristicsof the eight tubular composite actuator was presented. A prototype motor was designedand fabricated. The test results of the motor character were in accordance with thetheoretical analysis well. The angular speed of the rotor possesses a good linearity withthe driving voltage amplitude. At static, the moving trace of the stator tip is not an idealcircle, which is caused by piezoelectric hysteresis. Motor can work in the vicinity ofthe resonant frequency. With a driving voltage of 200V_p-p at 5.0kHz, the motor can rotateatthehighestangularspeedof319rpmwithnoloadandproduceamaximumstalltorqueof1.6mNm, respectively. Whenthedrivingvoltageis160V_p-p withafrequencyof5.0kHz andpre-pressureof0.3N,themotor’smaximumefficiencyreaches12%,andthe maximum output power is 7mW.A novel centrifugal piezoelectric pump using piezoelectric tubular composite ac-tuator is introduced. It has no sliding parts and so is supposed to have higher efficiency.it is not sensitive to the quality of the pumping liquid as neither precision valve nor mi-cro channel is needed. Due to the independent control of each single piezoelectric tube,a variety of piezoelectric pumps may be derived from this structure. Its static and dy-namic characteristics were analyzed in theory. The static deflection, the output torque,resonant modes and the influence of liquid flow rate on the resonant frequency werestudied. A prototype was produced and performance testing was conducted. The ex-perimentsresultsshowthatwhenthedrivingvoltageis120V_p-p atfrequencyof232Hz,the pump can pump stilled water at a flow rate up to 7.7ml/min under a backpressureof 2.0kPa. With a driving voltage of 120V_p-p at 233.2Hz, the pump can pump stilledwater at a maximum flow rate of 8.6ml/min and sustain a maximum backpressure of5.4kPa, respectively.Based on the above researches, the following points are pioneering work of thisdissertation: （1）ThepiezoelectriccoefficientsandYoung’smodulusmatrixofthetubu-lar composites were discussed in detail, together with the stress and electric potentialdistribution under different loads. （2） Actuator made from four tubular composites issuperior to the traditional single-tube actuator with quartered electrodes, which can bereplaced in scanning tunneling microscope. （3） A two phase traveling wave piezoelec-tric motor was developed using eight tubular composite actuator. It usually outputslarger torque than the piezoelectric motors based on single tube actuator. （4） A nov-el centrifugal piezoelectric pump using piezoelectric tubular composite actuator is de-signed and it has advantages of simple structure, convenient control, stable output andhigh frequency operation.The results in this paper have both theoretical and practical value for optimized de-signofpiezoelectrictubularcompositeactuators, thepropertiesanalysisoftheactuatorsand exploration of applications of piezoelectric actuating technology.更多还原