Embedded Ultrasonics for SHM of Space Applications.

摘要

The project explores application of embedded ultrasonics for monitoring integrity of space structures. Particular attention is given to the acoustic-elastic method for assessing the condition of bolted joints. The utility of the method is demonstrated for bolted structures of simple and complex geometries. The method allows for locating a loose bolt based on temporal variation of signal phase and, in structures of simple geometry, inferring correlation between torque on a bolt and associated shift in the phase of the elastic wave. A baseline-free acousto-elastic method was developed and validated on several representative structures. The opportunity to infer material parameters and boundary condition variations from embedded ultrasonic tests is highlighted. Acousto-elastic detection of a loose bolt is validated in tests involving the Plug and Play satellite and a suborbital payload. Sensor statistics and shielding are considered. It is advocated that the acousto- elastic structural health monitoring method may find a broad range of applications in space industry, particularly in pre-launch qualification and diagnosis and re-certification for a next flight.