Application of system-identification techniques to health monitoring of on-orbit satellite boom structures

The integration of composites into spacecraft is challenged by the risk of damage initiation and propagation during storage, launch, and service life. Elastically deployable composite booms are being developed for space utility. Matrix cracks are considered a primary form of damage caused by packaging before launch. However, while on orbit, most damages are induced by the environmental effects on the polymers. A well-developed structural health monitoring system will provide information for the dynamic control of the satellite and the condition of the deployable mechanisms on the space vehicle. A structural health monitoring methodology, based on the system-identification techniques, is proposed to identify the structural degradation in laminated composite booms. Nondestructive evaluation techniques, frequency-response analysis and autoregressive with exogenous input models are used to approximate the transfer functions between input and output sensing signals. Structural degradation is identified by examining the change of transfer functions at different storage states. A single-input/single-output approach is adopted in this paper. The proposed methodology is validated through experimentation in which matrix cracking is gradually induced by packaging the sample.