Analytical Study of Whole Flexible Spacecraft Vibration Isolation

Improving the dynamic environment provided to a spacecraft by a launch vehicle is of great importance to the safety and reliability of the spacecraft. An approach is to replace the existing payload attachment fitting with a vibration isolation device. Modern spacecrafts usually are highly flexible and this raises such questions as how to design the isolation device and evaluate its performance. By simplifying the device as single axis isolation, which can be realized by a proper design, the vibration isolation of whole flexible spacecrafts is analytically studied. From the study, it is identified that damping of the device is crucial to its performance and the isolation frequency loses its original meaning, after which the vibration transmissibility should be less than one. The coupling effect of the launch vehicle’s flexibility on the isolation is also important to the effect of the isolation and a coupling analysis is essential for ensuring the isolation performance. Because of the importance of the isolator’s damping in reducing the vibration transmissibility and the vibration of the coupled structure formed by the launch vehicle and the spacecraft, it is more appropriate to describe the vibration isolation of the whole spacecraft as vibration attenuation. A numerical example is also provided for further explaining those conclusions derived from the analytical studies.