Experimental study on on-orbit and launch environment vibration isolation performance of a vibration isolator using bellows and viscous fluid

Abstract

Operation of various actuators on a satellite such as reaction wheels, cryocoolers, etc. produces micro-vibration which may have adverse effects on the performance of high precision payloads. In order to protect the high precision payloads from the vibration disturbances, vibration isolators are often applied in the vibration propagation path. Vibration isolators developed for on-orbit space application should be able to isolate micro-vibration when in orbit, and also withstand severe launch vibration environment. In this paper, on-orbit and launch environment isolation performance of a vibration isolator using bellows and viscous fluid is evaluated. For the on-orbit environment test, a test setup was prepared inside a thermal-vacuum chamber and the transmissibility of the vibration isolator was measured to examine the effects of on-orbit space environment on the isolation performance of the developed isolator. The isolation test performed in a vacuum condition revealed problems caused by the elongation of the bellows due to the pressure difference which were addressed by sealing the viscous fluid inside the bellows at a vacuum condition. The effect of temperature variation on the isolation performance was found to be confined to the narrow frequency region around the isolator's resonant frequency due to the isolator's three parameter configuration. This result implies that the isolation performance of a vibration isolator having temperature dependent damping can be made less sensitive to the temperature variation by implementing three parameter configuration. The developed vibration isolator is designed to survive large deformation without being permanently deformed to guarantee the structural safety of the isolator in the launch environment. The structural safety of the isolation system is evaluated through sine and random vibration and shock tests. The on-orbit and launch environment test results indicate that the developed isolator can provide effective isolation for the small amplitude vibration disturbances on-orbit and also survive the large amplitude vibration during launch without any damage.