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The effect of tangential elasticity of the contact layer between stator and rotor in travelling wave ultrasonic motors 总被引:2,自引:0,他引:2
In travelling wave ultrasonic motors the elliptical motion of material points of the stator drives the rotor due to frictional mechanisms. The motor characteristic strongly depends on the mechanical properties of the components stator, rotor and contact layer. In order to predict the motor behaviour, a model for the contact between stator and rotor has been developed. The goal of the present paper is to point out the importance of the tangential elasticity of the contact layer which is responsible for the formation of stick zones and also for the amount of friction losses and overall efficiency. Therefore a comparison with a model with a contact layer rigid in tangential direction is given. Based on a visco-elastic foundation model for the contact layer, torque-speed curves as well as torque-efficiency curves are computed. Experimental investigations for identification of parameters, check of assumptions and model validation are carried out. Finally, the model is used to show the results of parameter variations for normal force, vibration amplitude and modulus of elasticity of the contact layer. 相似文献
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摩擦材料是超声波电机的关键零件,其应用方式直接影响超声波电机的驱动特性.以行波超声波电机为研究对象,将摩擦材料分别应用到转子和定子上,与相应的定子和转子组合,模拟超声波电机的接触方式,研究了超声波电机的负载和磨损特性随摩擦材料应用方式的变化规律.借助于阻抗仪测试了摩擦材料应用到定子齿面前后的阻抗特性,采用精密粗糙度仪和金相显微镜评价了超声波电机定子和转子接触界面磨损前后的形貌变化及其磨损模式.结果表明:当摩擦材料应用到定子齿面时,定子的谐振频率略微降低;当2台超声波电机空载转速相同时,摩擦材料应用到定子齿面与金属转子配副时可获得较大的堵转力矩,定子摩擦材料表面呈现抛光的磨损特征,而当摩擦材料应用到转子表面与金属定子配副时,转子摩擦材料表面呈现较严重的犁沟磨损. 相似文献
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机械结合面切向接触阻尼计算模型 总被引:1,自引:0,他引:1
针对两粗糙表面在法向力和切向力共同作用下相互接触时结合面切向阻尼的问题进行了研究。首先,根据KE模型对单个微凸体在弹性、弹塑性、塑性变形阶段的切向接触行为进行了分析,获得了微凸体在三个变形阶段的黏滑特性;然后,基于GW统计模型建立了一种在微凸体法向弹性、弹塑性和塑性变形机制基础上,考虑微凸体黏滑摩擦行为的机械结合面切向接触阻尼统计模型;最后,分别讨论了机械结合面的法向预载荷、切向激振频率和切向动态位移幅值对机械结合面切向阻尼的影响。研究表明:结合面切向接触阻尼系数随着结合面法向载荷的增大而增大,随着切向激振频率和切向动态位移幅值的增大而减小;在高频率、大幅值下,结合面切向接触阻尼系数几乎与动态位移幅值和激振频率无关。为了验证模型的准确性,构建了动态切向力作用下的结合面切向阻尼试验,其试验结果与理论仿真变化规律与量级基本一致,从而证明了本文所提出的切向阻尼模型的有效性。 相似文献
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面内行波超声电机定子表面质点运动轨迹与电机转矩 总被引:1,自引:1,他引:1
提出了面内行波超声电机的摩擦模型 ,研究了面内行波超声电机的动力传递机理 ,得出了电机的理想工作点 ,同时将电机的转矩和效率与定子表面质点的法向位移、切向位移及预应力相结合 ,提出为了实现电机大转矩和高效率 ,表面质点的法向位移应与转子接触区域质点的周向运动方向相同 .在满足上述条件的基础上 ,定子表面质点的切向位移和法向位移之比应尽量大 ,最佳比值应在考虑定子和转子之间的预紧力的条件下 ,使得电机工作于最大静摩擦力下 .最后采用有限元计算进行了验证 相似文献
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《Wave Motion》2017
The traveling wave ultrasonic stator is normally fabricated with teeth. The tooth geometry improves the driving speed, but it creates natural frequency splitting and mode contamination, especially a distorted traveling wave. A dynamic model of a stepped-plate periodic stator is developed to examine the distortion. The stator is treated as an annular supported by a thin mid plate, and the support stiffness is formulated by using equivalent energy principle. The effects of the tooth and mid plate on the natural frequency and vibration mode are examined by using the perturbation method. The rules governing the frequency splitting, frequency perturbation as well as mode contamination are also identified. The traveling wave response and elliptical trace on stator surface are obtained by using the mode superposition method and they are proved to be distorted due to the tooth geometry. The response at the repeated doublets becomes coupled forward and backward traveling waves, but that at the split doublets becomes coupled forward traveling, standing and backward traveling waves. The results indicate that the tooth mass instead of the stiffness decreases the vibration amplitude and driving speed of the dominant wave, but their effects are different at the repeated and split doublets. Inspection of the model implies that the distortion can be suppressed by using a suitable combination of the wavenumber, tooth count, tooth height and occupying fraction. Numerical calculations are carried out to demonstrate the tooth geometry effect on the transient waveform, driving speed and elliptical trace. The optimization of the tooth geometry that can help achieve a purer traveling wave is discussed. 相似文献
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The present paper investigates optimization rules and new design methodologies dealing with the contact mechanics in rotative travelling wave ultrasonic motors (TWUM). The proposed approaches focus on the design of the rotor, including the friction layer that is usually deposited onto its lower surface, while the stator is supposed to be preliminary designed. Contact aspects such as the transmission of mechanical power as well as the wear mechanism of the friction layer are investigated, according to the analysis of the stator–rotor contact mechanics in both hoop and radial directions. Considering a classical wear criterion in a preliminary step, a contact ratio, that allows the mechanical power to be optimized, is pointed out in the hoop direction. In a further step, the contact conditions in the radial direction are improved through the elastic fitting of the stator and rotor radial deflexions, therefore allowing the material's wear to be decreased. Some experimental tests, that have been recently performed, give a comparison of wear marks, which occur onto optimal and non-optimal rotor geometries. A first mechanism synthesis is finally proposed in such a way to allow the mechanical architecture of the rotor (including the friction layer) to be automatically designed according to a given set of mechanical constraints. 相似文献
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预压力对超声电机输出特性影响的实验研究 总被引:7,自引:0,他引:7
利用实验方法研究了预压力对行波超声电机摩擦界面输出特性
诸如空载转速、堵转扭矩等等的影响;对实验结果进行了详细的分
析,得出了一些规律性的结论,指出预压力存在一优值范围,可通过
预压力的调节来调整超声电机的输出特性;对现有摩擦驱动模型的仿
真结果进行了验证,提出了对现有模型的改进意见,为行波超声电机
摩擦界面的设计提供了依据. 相似文献
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Second-order approximation of primary resonance of a disk-type piezoelectric stator for traveling wave vibration 总被引:1,自引:0,他引:1
Considering the quadratic nonlinear constitutive relations of piezoelectric materials, a traveling wave dynamic model for
a lead zirconate titanate stator of a traveling wave ultrasonic motor is established using Hamilton’s principle and the Rayleigh–Ritz
method. Applying the method of multiple scales, the second-order approximation of the primary resonance for traveling wave
vibration of the stator is investigated. The second harmonic component is found in the primary response of the stator, which
arises from the quadratic stiffness in the condition of weak excitation. In the region of the resonance, the two coupled modals
are split and the lower-order peak bends to the left, hence a jump and delay exist in the response. In this way numerical
results are given to verify the feasibility of the analytical approach. The results provide a theoretical foundation for further
nonlinear dynamic analysis and design of the traveling wave ultrasonic motor. 相似文献
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单相旋转型驻波超声电机的数学模型及仿真 总被引:1,自引:0,他引:1
尽管单相驱动的旋转型驻波超声电机的原理样机早巳研制成功,但对这类电机的运动机理的研究却一直局限在定性分析上。本文将从能量角度,根据Hamilton变分原理,定、转子摩擦界面采用纯滑动模型建立了该种电机的数学模型;并根据此模型,用MATLAB语言作了计算机仿真,得到了该种电机的开、关过程动态响应。 相似文献
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This paper presents theoretical analyses and experimental investigations of a mechanical seal subjected to axial impulses of one of its mating rings (stator). The amplitude of oscillations of stator depends on the pressure of sealed fluid. The frequency of oscillations is influenced by the geometry of frontal faces of the seal rings and depends on the rotational speed of rotor. The analytical models include the analyses of the static equilibrium of the investigated mechanical seal and the dynamic response of stator. The experimental analysis implies the conception of the testing system, the experimental estimation of the leakage and the measurements of amplitude and frequency of oscillations. During operating time, the experimental variations of leakage of a mechanical seal with oscillating stator are monitored for different rotational speed of rotor. Finite element analysis is used to visualize the stress distribution of stator as a function of the applied forces. 相似文献
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Sliding friction in the presence of ultrasonic oscillations: superposition of longitudinal oscillations 总被引:1,自引:0,他引:1
W. Littmann H. Storck J. Wallaschek 《Archive of Applied Mechanics (Ingenieur Archiv)》2001,71(8):549-554
Summary It was often observed that friction forces can be reduced significantly if ultrasonic oscillations are superposed to the
macroscopic sliding velocity. This phenomenon can be used to improve machining processes by addition of ultrasonic vibration
to tools or workpieces, and forms the basis for many processes of ultrasonic machining. On the other hand, ultrasonic vibrations
can be used to generate motion. The thrusting force of ultrasonic motors is provided to the rotor through friction. In the
present paper, a simple theoretical model for friction in the presence of ultrasonic oscillations is derived theoretically
and validated experimentally. The model is capable of predicting the reduction of the macroscopic friction force as a function
of the ultrasonic vibration frequency and amplitude and the macroscopic sliding velocity.
Received 22 November 2000; accepted for publication 6 February 2001 相似文献
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超声马达摩擦学及其摩擦材料研究进展 总被引:22,自引:4,他引:22
超声马达是一种新型原动机,与普通电磁马达不同,这是一种摩擦驱动马达.为了促进超声马达的发展,对其研究中关于定子与转子界面接触驱动特性和摩擦磨损特性,超声波振动对定子和转子接触界面摩擦学特性的影响,转子摩擦材料的选择及其寿命预测等,从摩擦学角度对国内外的研究进展进行了综合归纳与评述,并且针对超声马达摩擦驱动的特点,提出了当前值得重视的一些研究内容. 相似文献
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定子表面织构对超声电机性能的影响 总被引:1,自引:0,他引:1
针对超声电机摩擦材料磨损严重和温升高的问题,采用在定子表面加工微织构的方法,提高了电机机械特性并降低了摩擦材料磨损. 首先,用显微镜测量超声电机定子表面摩擦材料黏着区域,设计出三种不同密度的凹坑织构,采用激光的方法加工在定子表面;然后,测试超声电机负载特性、效率特性和温升特性并观察定子表面. 结果表明:3-凹坑织构定子电机空载转速最高,相比光滑定子电机高出12.1%,5-凹坑织构定子电机堵转转矩和最大效率最高,分别高于光滑定子电机13.04%和17.1%,同时电机的温升也有所降低. 通过观察定子表面发现,凹坑织构有大幅降低摩擦材料黏着的作用,这种作用可以增加电机接触界面能量转换效率,提高了电机的性能并降低了摩擦材料的磨损. 相似文献
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实际工程表面多为粗糙表面,研究粗糙表面的表面形貌对微动接触中压力和应力的影响具有重要意义。本文研究接触过程中法向载荷保持不变,切向载荷为周期性的交变载荷。首先,建立接触算法和模型,算法核心是利用共轭梯度法CGM(Conjugate gradient method)计算微动接触中的表面压力及切向应力并利用快速傅里叶变换FFT(Fast Fourier transform)加快计算速度。然后,对单峰表面、正弦表面和随机粗糙表面的接触进行数值研究。结果表明,表面幅值对切向载荷-位移曲线以及接触过程中的能量耗散有影响,表面幅值越大,相同切向载荷作用下产生的切向位移越大,能量耗散也越大。 相似文献
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超声马达转子摩擦材料厚度对驱动性能的影响研究 总被引:5,自引:0,他引:5
制备了一系列不同厚度的摩擦材料 ,利用超声马达摩擦特性模拟试验装置 ,研究了摩擦材料厚度对超声马达空载转速和堵转力矩的影响 .基于一个简化的行波超声马达定子和转子接触模型 ,用有限元法计算了定子和转子接触变形随摩擦材料厚度的变化规律 ,提出了定子和转子具有合理接触变形的摩擦材料厚度范围 .根据试验和理论计算结果确定了摩擦材料最佳厚度 ,为超声马达摩擦材料厚度设计提供了理论依据 相似文献
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The results of a theoretical investigation into ultrasonic linear normal wavefields in anisotropic three-dimensional bodies with mechanical orthorhombic symmetry are presented. A detailed study is made of the dispersion dependencies for higher normal wave modes in a single-layered orthorhombic plate-type waveguide. Moreover, the distribution of complex branches corresponding to the edge standing wave modes is studied and their role in the transformation of the entire spectrum upon a change in the travel direction in the waveguide plane is analyzed. A new type of localization of the higher modes of high-frequency short-range normal waves in a crystal layer is described. An efficient method is developed for studying the spectrum of ultrasonic normal waves in a circular cylindrical waveguide made of an orthorhombic monocrystal 相似文献