Study on the Vibration Displacement Distribution of a Circular   Ultrasonic Motor Stator
  In this paper is presented a theoretical consideration on the stator's displacement distribution, which is one of the most important problems in defining the structure of the circular ultrasonic motor stator. The results are compared with results obtained utilizing holographic interferometer, laser vibrometer and a FEM (finite element method) simulation. They are in a good agreement with each other. 
Chol-Su Ri, Myong-Jin Kim, Chol-Su Kim, Song-Jin Im
physics.optics