Friction drive of an SAW motor. Part III: Modeling

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 55; no. 10; pp. 2266 - 2276
• Main Authors: Shigematsu, T., Kurosawa, M.K.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-10-2008; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic waves; Acoustics; Acoustics - instrumentation; Bridges; Computer Simulation; Computer-Aided Design; Displacement measurement; Drives; Elasticity; Equipment Design; Equipment Failure Analysis; Exact sciences and technology; Finite element analysis; Finite element methods; Friction; Friction drives; Fundamental areas of phenomenology (including applications); General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mathematical analysis; Mathematical models; Micro-Electrical-Mechanical Systems - instrumentation; Models, Theoretical; Motion; Motors; Numerical simulation; Physics; Stiffness; Stress; Studies; Surface acoustic waves; Transducers; Transduction; acoustical devices for the generation and reproduction of sound; Acoustic wave device; Stress analysis; Point contact; Surface layer; Acoustic surface waves; Mechanical contact; Modeling; Finite element method; Friction; Ultrasonic motors; Friction coefficient; Linear motor; Reliability
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.925

A 2-layer modeling method of friction drive of a surface acoustic wave motor is proposed. The surface layer accounts for the previously proposed point-contact friction drive model, which was generalized to correspond spatially to the underlying layer that is comprised of a 3-D elasticity field. A method to determine stiffness through the use of analytical solutions of 3-D contact problems bridges the 2 layers. Because the determined stiffness expresses the accuracy of the results regarding either layer, the validity of the results concerning the stiffness and the resulting stress field was evaluated by comparison with the results of finite element analysis. Furthermore, we executed numerical simulations by using the friction drive model, which were compared with the measured displacements of the frictional surface of the slider. The simulation accurately represented the normal displacement of the frictional surface; the modeling procedure in the normal direction was found to be reliable. However, because the friction coefficient drastically changes the tangential displacement, we could not discuss the reliability of the modeling procedure in the tangential direction. A thorough discussion of the friction drive would thus require further investigation of the friction phenomena.