旋转行波超声电机非线性摩擦界面模型

分析了对行波超声电机定子和转子间接触状态，利用间距δ更准确地表征了定、转子间几种不同的接触情况；依据行波作用的特点，利用时空方程间的对应关系，提出了用接触变形角定量地表示定、转子间接触状态的变化情况，讨论了弹性滑动、弹性滞后，特别是stick-slip现象对摩擦界面的影响；改进了传统的线性纯滑动摩擦模型．建立了非线性摩擦界面输出特性仿真分析模型。

Nonlinearly Frictional Interface Model of Rotated Traveling Wave Type Ultrasonic Motor

The contact layer between the rotor and stator of a traveling-wave type ultrasonic motor (USM) is analyzed. According to the equivalency principle, the frictional layer is simplified as a spring structure, and a nonlinear spring model of the rotor/stator interface is established. According to the characteristics of traveling-wave and the corresponding relationships between equations in space and time domain, two newly accurate parameters, the gap value and the contact-deformation angle, are presented to describe the different contact conditions of the rotor/stator interface. The influences of elastic glide, elastic lag and especially the stick-slip phenomenon upon friction interface are discussed. The traditional linear pure slip frictional model is improved and a new nonlinearly simulated model is established. The nonlinear model describes the output characteristics of the rotated traveling wave ultrasonic motor and simulates some former un-explainable experiment phenomena, such as the USM starts to work only when the amplitude is large enough and the USM does work when the preloaded force is too big, etc. The model simulates the USM output characteristics under different conditions of preloads, amplitudes and different frictional materials verified by the experimental results.