Title :
Effect of the hydrodynamic bearing on rotor/stator contact in a ring-type ultrasonic motor
Author :
Maeno, Takashi ; Bogy, David B.
Author_Institution :
Dept. of Mech. Eng., California Univ., Berkeley, CA, USA
Abstract :
A hybrid numerical analysis that includes the hydrodynamic bearing effect and elastic contact in a ring-type ultrasonic motor is presented. The two-dimensional time-dependent compressible Reynolds equation is solved numerically by a second-order time accurate, noniterative, factored implicit finite-difference algorithm. The rotor deformation is described by a one-dimensional Green´s function. The contact problem is solved by an iteration method so that the contact condition and the hydrodynamic bearing condition are satisfied simultaneously. The results show that the hydrodynamic bearing effect, especially the squeeze effect, is significant for ultrasonic frequency contact of the rotor and stator. Surface roughness, contact area, and normal vibrating speed of the stator are important parameters in the hydrodynamic bearing. A disagreement between the friction coefficient needed in the numerical analysis and the experimentally measured one in a previous study.<>
Keywords :
Green´s function methods; flow; numerical analysis; piezoelectric motors; Green´s function; air flow; contact area; contact condition; elastic contact; finite-difference algorithm; friction coefficient; hydrodynamic bearing; iteration method; numerical analysis; ring-type ultrasonic motor; rotor deformation; rotor/stator contact; squeeze effect; surface roughness; time-dependent compressible Reynolds equation; ultrasonic frequency contact; vibrating speed; Equations; Finite difference methods; Frequency; Green´s function methods; Hydrodynamics; Numerical analysis; Rotors; Rough surfaces; Stators; Surface roughness;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on