预压力对超声波电机特性的影响研究

为了降低旋转行波型超声波电机（TWUSM）运行过程中产生的噪声，研究了预压力对TWUSM模态频率以及噪声特性的影响.利用D’Alembert原理和假设模态法，建立了受预压力作用下TWUSM定子的一维振动模型和频率方程，通过分析该模型和频率方程，研究了预压力对TWUSM模态频率的影响.利用Hamilton原理和应力-应变、应变-位移及电势-电场之间的关系，推导了TWUSM定子的有限元(FEM)模型，研究了预压力对TWUSM振动模态混叠以及噪声特性的影响.结果表明,TWUSM模态频率随预压力的增加而升高，增加预压力可以避免TWUSM出现模态混叠现象和抑制TWUSM噪声强度.

Researches on effects to ultrasonic motor's performance of preload

To reduce the noise of the travelling wave ultrasonic motor(TWUSM) caused by its operation,the effects of the preload on the modal frequency and the noise characteristics of the TWUSM were studied.The one-dimensioned vibrating model and the frequency equation of the TWUSM's stator considering the preload were derived based on the D'Alembert principle and the modal-assumption method,and the effects of the preload on the modal frequency of the TWUSM were studied by analyzing the model and the frequency equation.According to the Hamilton principle and the relationships of stress-strain,strain-displacement and electric potential-electric field,the finite-element(FEM) model of the TWUSM's stator was deduced,and then the effects of the preload on the modal overlap and the noise characteristics of the TWUSM were studied.The results show that the modal frequency of the TWUSM increases with the increasing preload,and that the increasing preload can avoid the modal overlap and decrease the noise intensity of the TWUSM.