APPLICATION OF COMPLEX TDOFS IN FIXED BOUNDARY PAYLOADS VIBRATION TESTS

摘要

Force Limit Vibration (FLV) is used to decrease the over-testing problem associated with traditional vibration testing. The complex two-degree-of-freedom system (TDOFS) seems to give the most reasonable conservative force limits. However, the complex TDOFS model is based on free boundary conditions for the mounting structure, which is true for spacecraft mounted on a launch vehicle, but not necessarily true for other cases such as a payload mounted on a spacecraft, which requires fixed boundary conditions. In this work we set an example of fixed boundary condition, and compare the force limit predicted by the complex TDOFS method regarding the free boundary condition and the fixed boundary condition. The result indicated the force limit suggested by free boundary condition CTDOFS is not conservative enough in certain frequency band, while the corrected CTDOFS concerning fix boundary condition gives reasonable conservative force limit prediction. Some experimental methods to derive the mass parameter for the estimation of force limit is also presented.