ASA 127th Meeting M.I.T. 1994 June 6-10

4pSAa7. Statistical energy analysis prediction of a liftoff vibration environment in six degrees of freedom.

Robert E. Powell

Cambridge Collaborative, Inc., 689 Concord Ave., Cambridge, MA 02138

The liftoff vibration environment for a guidance control sensor was predicted in three translational and three rotational degrees of freedom using statistical energy analysis (SEA) methods. Excitations from airborne sound pressure and mechanical transmission from solid rocket motor internal sources were applied to an SEA model of the vehicle and motor structure. Model predictions of translational response and wavenumbers for radial and inplane motions were combined to estimate rotational velocity environments. The rotational velocities from the vibroacoustic response represented out-of-band noise for the control system (that is trying to properly gimbal the motor nozzle) and required pre-flight estimation so that an appropriate filter could be provided.