Dynamic Characteristics of a Hydrostatic Vibration Isolation Device

Abstract

In this study, we propose a new vibration isolation device using hydrostatic effect. The proposed device support an object with a piston combined with a cylinder. The proposed device consists of a variable restrictor whose fluid resistance changes in response to piston movement, a fixed restrictor whose fluid resistance does not change regardless of piston movement and a narrow annular gap between the piston and cylinder acts as a hydrostatic gas bearing. The hydrostatic gas bearing guides the piston movement in vertical direction and it also acts as a fixed restrictor. The larger the rate of change of the resistance of the variable restrictor to the displacement of the piston, the larger the static spring constant. If the static spring constant is larger than that of an equivalent air spring, the damping coefficient will be negative and the vibration isolation device will be unstable. Under conditions where the damping coefficient is positive, the smaller the static spring constant, the larger the maximum value of the damping coefficient.