A novel traveling wave ultrasonic motor using a bar shaped transducer

A novel traveling wave ultrasonic motor was proposed. The structure of the motor is rather simple and different from the conventional traveling wave ultrasonic motors. Its production processes are very convenient. It is composed of a stator constituted with a ring and a bar shaped transducer and two cone shaped rotors. The rotors were pressed on inner surface of the ring by means of a pre-pressure system. The bar shaped transducer has a sand- wich-like configuration,where two sets of piezoelectric element are bolted. One set excites a longitudinal vibration of the bar, and the other set excites a flexural vibration of the bar. The ring＇s traveling wave excited with the longitudinal vibration and the bending vibration of the bar transducer was simulated with FEM （finite element method）. The prototype of the motor was made and investigated experimentally for its performance. Its maximum torque and rotating speed are 0.25 N · m and 50 r/min, respectively.     

A ring type standing wave ultrasonic motor using cantilever type longitudinal transducers

The disadvantages of classic ring type ultrasonic motor were analyzed.To obtain large mechanical output power,a ring type standing wave ultrasonic motor using cantilever type longitudinal transducers was proposed.There are four pairs of cantilevers on one side of the ring,and four PZT ceramics are set between each pair of cantilevers.A screw fastened the PZT ceramics and cantilevers together to form a longitudinal transducer.The bending vibration mode of the ring is excited by the stretching vibration of the PZT ceramics.Thus,linear simple harmonic motions are achieved at the particle on the teeth.And the driving force is the frictional force between rotor and stator.The working principle of the proposed motor was analyzed.The ring and the longitudinal transducer were designed with FEM.The sensitive parameters of resonant frequency of the transducer and ring could be gained with modal analysis.The longitudinal vibration modal of transducer and bending vibration modal of ring were degenerated,and the motion trajectories of nodes on the teeth were analyzed.The results of this paper could guide the development of this new type of motor.     

Actuating mechanism and design of a T-type linear ultrasonic motor

To take advantage of merits of higher output-power and efficiency of bolt-clamped transducer,a T-type linear ultrasonic motor was proposed in this paper.The proposed motor contained a horizontal transducer and a vertical transducer.The horizontal transducer included two exponential shape horns,and the vertical transducer contained one exponential shape horn.And the horns intersected at tip ends where a driving foot was located.The longitudinal vibrations of transducers were excited by the stretching vibration of PZT ceramics.Longitudinal vibrations were superimposed in the motor and generated elliptical trajectory at the driving foot.The actuating mechanism of the proposed motor was analyzed.The two working modals of the motor were gained with FEM.The resonant frequencies of two working modals were degenerated by adjusting the structural parameters.The motion trajectory of nodes on the driving foot was gained by transient analysis.The vibration amplitude of node on the driving foot indicates that the proposed motor has potential good output characteristics.The results verify the feasibility of the proposed design and provide instructions for the development of the new ultrasonic motor.     

广义双耦合sinh-cosh-Gordon方程行波解的分支

运用平面动力系统理论、分支理论和直接方法,研究了广义双耦合sinh-cosh-Gordon方程,证明该方程存在无界行波解和不可数无穷多光滑周期行波解.并在不同的参数条件下,给出了该方程无界行波解和周期行波解存在的各类充分条件,在所给出的参数条件下求出了系统(3)的所有显示精确行波解.     

A new visco-elastic contact model of traveling wave ultrasonic motor with stator frictional layer

A new contact model of traveling wave ultrasonic motor (TWUSM) with a visco-elastic stator frictional layer was presented. In this model, the initial boundaries were revised, and the rotor revolution speed could be calculated iteratively. This model was compared with compliant slider and rigid stator model. The results of motor characteristics simulations showed that the motors based on this model would gain bigger stall torque. Then the friction and wear characteristics of two models were analyzed. The motors based on this model had lower coefficient of friction and better wear resistance.     

芯片键合纵弯复合超声换能器的设计与试验

为了解决当前采用一维纵向超声加载模式进行芯片键合时造成结合面不充分的问题,设计纵弯复合超声能量加载模式的压电超声换能器,实现轴向纵振和水平弯振复合的超声振动代替传统单一的轴向振动. 采用ANSYS软件,对换能器有限元模型进行模态分析和谐响应分析,得到换能器纵振和弯振模态的谐振频率及振型. 通过调节换能器结构尺寸,实现纵振与弯振模态的简并. 采用阻抗分析仪对样机的频率和阻抗进行测试,使用激光多普勒测振仪测试换能器的纵振与弯振幅值,测试结果与有限元仿真计算结果一致,发现纵向与弯曲振幅均随着驱动电压的增加呈近似线性上升趋势, 证明设计的压电换能器实现了纵弯复合振动.     

复合型USM压电扭振子设计及其特性分析

介绍利用国产压电材料设计纵扭复合型超声波电机(USM)压电扭振子的理论和制造工艺,主要内容包括:压电材料的选取,压电扭振子的结构,根据等效电路推导出电机扭转振动模式的谐振频率方程,以及扭振子尺寸计算公式;根据实验总结了压电扭振子的制造工艺、黏接及其注意问题.并利用阻抗频谱分析仪测试了按上述理论设计的压电扭振子的频率特性.结果表明:设计理论、黏接剂的选择以及加工方法是合理可行的.据此研制的样机最大输出力矩已达10 Nm以上.     

一种减小行波型旋转超声电动机径向滑移的方法

为了减小行波型旋转超声电动机定子与转子间的径向滑移,提出通过增大转子摩擦层径向最大剪切变形角的方法和基于定子与摩擦层间的黏滑原理来减小定子与转子间的径向滑移,分析了影响摩擦层的径向最大剪切变形角的因数;在ANSYS10.0中建立电动机定转子三维有限元接触模型;对影响定转子间径向滑移的因素进行仿真分析。分析结果表明,可以通过增大定子与摩擦层间的摩擦因子和增大摩擦材料的泊松比来减小电动机定子与转子间的径向滑移。摩擦材料泊松比的改变对减小径向滑移的贡献程度要大于定子与摩擦层间摩擦因子的改变对减小径向滑移的贡献程度。     

Contact analysis and modeling of standing wave linear ultrasonic motor

A contact model for describing the contact mechanics between the stator and slider of the standing wave linear ultrasonic motor was presented. The proposed model starts from the assumption that the vibration characteristics of the stator is not affected by the contact process. A modified friction models was used to analyze the contact problems. Firstly, the dynamic normal contact force, interface friction force, and steady-state characteristics were analyzed. Secondly, the influences of the contact layer material, the dynamic characteristics of the stator, and the pre-load on motor performance were simulated. Finally, to validate the contact model, a linear ultrasonic motor based on in-plane modes was used as an example. The corresponding results show that a set of simulation of motor performances based on the proposed contact mechanism is in good agreement with experimental results. This model is helpful to understanding the operation principle of the standing wave linear motor and thus contributes to the design of these types of motor.     

A new principle of traveling wave differential protection on series-capacitor-compensated transmission lines

Traveling wave differential protection has the ability,in theory,to entirely eliminate the effects of distributed capacitive current,but it cannot be applied on series-capacitor-compensated lines directly.In this paper,unbalanced output of conventional forward and reverse traveling wave differential currents under normal operating conditions and external faults was analyzed.A new type of traveling wave differential current was defined by combining forward and reverse traveling wave differential currents.Expressions of the defined differential current when internal and external faults occur were deduced.On this basis,a new principle of traveling wave module differential protection on series-capacitor-compensated lines was proposed,and characteristics of module differential current under different faults were analyzed.The priniciple is immune to line distributed capacity,series capacitor positions,and presence or absence of MOV breakovers.The validity of this scheme was verified by PSACD simulations.     

The experimental study of the calibration of the focus ultrasonic transducer on its picture

The shape and size of the energy transducer‘ s focus decide the constitution of the cure project using HIFU ( High intensity focused ultrasound). The parameter of the focus will be different when the structure of the transducer is different, so we must calibrate each of them. This paper represents calibration principle and method of focal territory in a high-power ultrasonic focus transducer. The experiment is performed on our designed multiple wafer concave focus probe and HIFU apparatus, using 1010 nylon and pork as the target range.It can be seen that the geometric center and focal territory acoustic field center cannot match together. When using nylon as the target, the distributed curves and theoretical curves are a better match. Therefore, the method and principle of calibration here is constructive for the calibration on pictures of other types of HIFU apparatus.     

锦纶织物超声波纳米颗粒复合化学镀镍磷

分别使用十二烷基苯磺酸钠、十六烷基三甲基溴化铵和海藻酸钠分散纳米Al2O3、Si3N4和ZrC颗粒,并将其添加到化学镀镍液中;在超声波辅助条件下对锦纶织物进行纳米颗粒复合化学镀镍磷;借助SEM、EDX、XRD和TG测试技术对镀层表面形貌、成分、结构和织物热性能进行研究,并测试织物阻燃、耐磨和电磁波屏蔽性能.结果表明:与普通化学镀镍磷织物相比,不同纳米颗粒复合化学镀镍磷织物镀层表面形貌有所不同;结晶度增大,当纳米颗粒添加量不大时,晶粒尺寸有所减小;热起始分解温度降低(纳米Si3N4除外),耐高温分解温度升高,燃烧速度有所减慢,没有熔滴现象发生;电磁波屏蔽效能变化不大,随着增重率的增加,平均屏蔽效能逐渐增大,表面电阻减小;耐磨性能增强.     

三自由度行波型超声波电机的静力学分析

从三自由度行波型超声波电机的驱动原理与基本结构出发，使用变换矩阵得到了定转子的位置变换关系，进而分析了球转子的受力情况，并给出了定转子接触圆周的接触力方程.根据球转子和各个行波定子的力平衡方程，得到了球转子球心的微位移和行波定子的轴向压紧量与行波定子的轴向压紧力的关系方程.仿真分析表明，对电机定子施加对称的压紧力、增大定子轴线与基本坐标系轴线的夹角和减小定子半径，能够减小定转子接触圆周上定子与转子不相互接触的区域，使电机性能得到充分发挥.     

U形直线超声电机结构设计

针对直线超声电机的小型化问题,提出一种新型U形直线超声电机,该电机由U形定子和导轨组成,压电陶瓷片采用粘贴的方式固定在定子上.研究了电机的激振方式与位置,设计并加工了直线超声电机样机和测试装置.将柔性铰链结构应用到直线超声电机夹持中.通过实验确定了电机的最佳工作频率、预压力.研究了输出力和空载速度随工作频率、预压力和电压的变化规律.实验表明,电机在电压值400 Vpp,预压力25N条件下,最大空载速度470 mm/s,最大输出力9N,定子质量25 g,推重比达36;柔性夹持能提高电机的模态一致性和效率,同时简化了电机结构.该研究为电机小型化发展奠定基础.     

Optimal design of butterfly-shaped linear ultrasonic motor using finite element method and response surface methodology

A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 mm/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.     

Numerical studies of stepwise radial fuel shuffling in a traveling wave reactor

The concept of travelling wave reactor(TWR)applies the mechanism of self-sustaining and propagating nuclear fission travelling waves in fertile media of 238U and 232Th to achieve very high fuel utilization.Based on this concept,a stepwise radial fuel shuffling strategy was proposed and applied to a sodium-cooled fast reactor(SFR)loading metallic 238U fuel.The multi-group deterministic neutronic code ERANOS with JEFF3.1 data library was used as a basic tool to perform the neutronics and burnup calculations.The inward fuel shuffling calculations were first performed in a 1-D cylindrical case for parametric understanding,and then extended to a 2-D R-Z case.The shuffling calculations for the 1-D and 2-D SFR model yielded some interesting results.The asymptotic keff varied parabolically with the characteristic fluence,while the burnup increased linearly.The highest burnup achieved in 2-D case was 38%.The power peak shifted from the fuel outlet side(core centre)to the fuel inlet side(core periphery)in both 1-D and 2-D cases and the corresponding peaking factor decreased dramatically along with the characteristic fluence.The present research demonstrated that the proposed stepwise radial fuel shuffling in the sodium fast reactor achieved the characteristics of the traveling wave reactor.     

Fabricated and friction test anisotropy material of ultrasonic motor

The twisters for composed of anisotropic material were designed and manufactured.And two kinds of directional-composites were made:one was fiber direction vertical with frictional interface and another was parallel with frictional interface and moving direction.By varying the proportions of epoxy resin and fiber and arranging the orientations of fiber,the composites anisotropy along longitudinal and circumferential were got.Using density measurement,the mass fraction of resin and fiber were calculated.According to composite meso-scopic mechanics,the elasticity constants of composite were analyzed and calculated.The composite different thicknesses were sliced,and attach to the rotor,then the load characteristics,no-load speed,stop load of ultrasonic motor(USM)were test.The output properties of USM with 0.6 mm thickness composite were superior.The effect of friction material on ultrasonic motor was analyzed.Elastic modulus,thickness and micro-morphology of material are main factors which affect characteristics of ultrasonic motor.     

电磁超声表面波辐射声场的三维有限元分析

为了得到电磁超声表面波换能器在被测试件表面和内部的辐射声场分布,采用ANSYS有限元仿真软件对电磁超声换能器辐射声场进行仿真.建立了电磁超声换能器三维有限元模型并进行了优化,给出了被测试件中感生涡流与换能器激励线圈参数的量化关系.通过电磁结构耦合的方法得到被测试件内部及表面不同方向质点的位移变化,分析了在被测试件内部的辐射声场分布,并给出了被测试件表面辐射声场的指向性规律.根据仿真模型搭建了电磁超声探伤平台,实验结果与指向角仿真结果基本吻合.实验结果表明：对电磁超声表面波辐射声场的有限元仿真,为其设计优化、实际探伤范围的确定、接收线圈放置位置,以及收发装置的安装角度提供了依据.     

Design and optimization of the piezoelectric micromechanical ultrasonic transducer with an AlN thin film

Because existing ultrasonic transducers mostly use PZT and ZnO materials as piezoelectric thin films, while the PZT contains lead and ZnO has the problem of contaminating CMOS manufacturing, a piezoelectric ultrasonic micromechanical transducer with circular bi-laminate bending vibration which uses the aluminium nitride as the piezoelectric layer is designed. The working principle of the transducer is analyzed, the finite element model is established, and the finite element simulation is carried out for the size parameters of the transducer. It is found that the resonant frequency of the transducer is proportional to the thickness of each layer and inversely proportional to the square of the radius of the transducer; when the radius of the upper electrode is about 65% of the radius of the transducer, the resonant amplitude of the transducer is the largest; when the thickness ratio of the silicon and the aluminum nitride of the piezoelectric layer is about 0.6, the resonant amplitude is also the largest. The optimized transducer is simulated and compared with the original model. The results show that the working frequency in air is 9.21MHz, the electromechanical coupling coefficient increases from 21.44% to 27.16% in air and from 3.55% to 11.93% in water. These conclusions provide basic data for the research on the medical imaging probe.