Comment
Being pressed by a force P per unit wavelength (not shown here), the profile of the Rayleigh wave changes. Here, the displacements distribution taken from the exact solution of the problem of smooth contact [19] is depicted. Initial elliptical trajectory of the particle motion (red) is also disturbed. If friction between the stator (half-space) and the rotor (rigid strip, green) is presented, the latter begins to move in the direction opposite to the wave propagation. The rotor velocity is determined by the particle velocity and is much smaller than the wave velocity.
Results concerning the theory of the travelling wave ultrasonic motor are also presented in the author's papers 20, 21, 24 and 25 and conference proceedings 5, 6, 8 and 9.