Dynamic Analysis of Composite Stator of Ultrasonic Motor Based on Substructure Interface Loading Theory

Due to its compact sizing, fast response and good control performance traveling wave type rotary ultrasonic motor (TRUM) has significant potentials for applications in robot actuation. Moreover the dynamic characteristic of composite stator contributes much to the performance of TRUM. In this paper a new modeling strategy for the composite stator of TRUM has been developed. First the composite stator is divided into several simpler substructures, and a kind of semi-analytical annular element is applied to mesh inner web and outer annular composite plates. Then each tooth on top of stator is described by hexahedron isoparametric element with 8 nodes and its dynamical contribution (including stiffness and mass) to the substrate is calculated based on substructure interface loading theory. So the unknown degrees of the freedom are reduced and the higher computational efficiency and more accurate result will be achieved. At last the substructural modal synthesis theory is applied to derive the whole stator by integrating the substructures. In the end the computational results are found to be in good agreement with those from experiments and it is proved that the proposed model in this paper allows for quick and precise dynamical analysis of the composite stator. Moreover the harmonic response analysis denotes the motion of the point on the top of the composite stator is three dimensional. So it suggests that the three dimensional contact mechanisms exist on the contact interface between the stator and rotor.