Study On The Linear Ultrasonic Motor Based On In-plane Bending Modes Of Piezoelectric Rectangular Composite Laminated Plates

Linear Ultrasonic Motor(LUSM)is a vital branch of ultrasonic motors, which has become focus with it's advantages of simple structure, high torque at low speed, high-retention torque, good controllability, compactness, high precision, faster transient response, silence, no electromagnetic field induction, etc., which make them very suitable for the application in miniaturization or micro-miniature, precision positioning, micro-robotics, automation, information (e.g. magnetic head) and other applied fields. In this study, a new type of linear ultrasonic motor based on two different in-plane bending modes of piezoelectric rectangular composite laminated plates intended to apply to magnetic head drive are presented and developed, and the vibrator and its motion mechanism have been investigated theoretically and experimentally. The main contents in the study as follows:Firstly, the present state in the studies and applications of the linear ultrasonic motor has been surveyed, the features and types are summarized, and the key problems on its investigations and applications have been discussed, especially for the linear ultrasonic motor based on the in-plane modes of piezoelectric rectangular plate.Secondly, based on the theories of elastic mechanics and vibration, the free in-plane vibration of piezoelectric rectangular composite laminated plates was investigated. The dynamical model of vibrator has been established, and the in-plane frequencies are calculated by using the Rayleigh-Ritz method and Algebra package Maple. The convergence of the method is verified by comparison with the analytical results which are available for the free plates. The effects on the in-plane bending frequencies for the different metal materials or dimensions or properties of the vibrator are analyzed. The relationship between the vibration modes and the geometrical dimensions of vibrator are obtained. Its convergence is verified by comparison with the ANSYS solution. Then, the structure of the vibrator has been theoretically designed.Thirdly, the free in-plane vibration of the vibrator are analyzed by equivalent circuit method, and the equivalent circuit is obtained based on the first class piezoelectric equations, in which the in-plane vibration is regard as the coupling of longitudinal vibration at length and width. According to the equivalent circuit, the resonance frequency equation is derived and the resonance frequencies are calculated.Fourthly,according to the theoretical analysis, a new type of linear ultrasonic motor based on the in-plane bending modes of rectangular composite laminated plates has been designed. The excitation of the working vibration modes and working principle of this kind of motor have been analyzed and discussed.At last, a motor sample for the new type of linear ultrasonic motor was fabriced, the experiments of sweeping and impedance for the vibrator are done by Aligent 4294A and impedance analyzer, and its performance was evaluated experimentally. The experimental results show that the error of the optimum excitation frequency comparison with the swept results is 0.18% and 0.18% respectively, and the new motor offers identical performance in both directions, the maximum average velocity of motor is 458.3mm/s, the maximum drive force is 1.2N while the signal frequency is 65.2kHz and 380VP-P. Therefore the correctness of the relevant analysis and design in this paper is obtained. This investigation is beneficial to the study for the LUSM based on the in-plane vibration of piezoelectric rectangular plate and its application in information industry.