Squeeze-film air damping of thick hole-plate

The damping effect of air flow in holes is considered based on Poiseuille equation and the damping effect of lateral flow is considered by conventional Reynolds' equation for infinite thick hole-plate. The expression for damping ratio is obtained and the conditions for minimum damping ratio can be found.-A modified Reynolds' equation is established for thick hole-plate with finite dimensions. The equation is a good approximation for hole-plates in typical MEMS devices. As it is also effective for non-hole-plate as well, it is more general than the conventional Reynolds' equation. The distribution of damping pressure under a hole-plate can be found by solving the modified Reynolds' equation with appropriate boundary conditions. As an example, the damping pressure of squeeze-film air damping of a long rectangular hole-plate is considered. Analytical expressions for the damping pressure, damping force and damping ratio are found. (C) 2003 Elsevier B.V. All rights reserved.