Vibration test condition for spacecraft lift-off environment

The purpose of the vibration test of spacecrafts is to assess their adaptability to low-frequency vibration environment during lift-off. This paper gives the simulation of the satellite ground vibration test (GVT) and the state of the satellite along with rocket during lift-off. The simulation results of these two states are compared on condition that the lateral vibration of satellite/launching vehicle (S/LV) interface is the same. It is shown that the dynamic responses of satellite vertex are totally different. This is because there is angular motion of S/LV interface during lift-off, but in the GVT, the angular motion is restrained. By means of numerical simulation of the lift-off state, the angular motion related to the translation motion of S/LV interface can be determined. Then, using this angular motion as supplementary condition to simulate the vibration test, the calculated dynamic responses of satellite vertex are identical with the lift-off state. It demonstrates that supplementing angular motion condition is an effective method to improve spacecraft ground vibration test more identically with the real lift-off environment. Furthermore, it is useful for the application of the multi-degree-of-freedom shaking table, and provides the basis for test condition requirement.