SAW based rotation force of a cylindrical solid

It was shown experimentally in [1] that a macroscopic cylindrical solid can be rotated due to the excitation of two counter-propagating surface acoustic waves (SAWs) with different amplitudes on its surface. The arising distributed rotation force has been estimated phenomenologically in the partial case of a piezoelectric tube with a ring unidirectional electrode transducer (RUDT) using the torsion pendulum equation of motion. It was found that the rotation force is proportional to the square of the applied voltage. The cylindrical rotating structure can be considered as a new kind of stator free motor that needs to be investigated and optimized for potential future applications. The objective of the present work is the attempt to give the first estimation of the rotation force on the basis of physical principles and equations of motion in periodic structures. This approach makes it possible to relate the rotation force with material parameters and geometry of the structure.