Development of an Active Sensing Method for Health Monitoring of Solid Rocket Motors

摘要

Aging processes in solid propellant can lead to defects, such as cracks and grainlinerrnseparations, that limit the service lifetime of solid rocket motors. Due to the concernrnfor the reliability of aging motors, over the years various methods have been used to tryrnto determine whether a grain is defect free and where along the aging process anrnindividual motor is. Non destructive evaluation methods, such as X-ray radiography andrnultrasonics, and aging models are typically used to asses the integrity of solid rocketrnmotors and predict the material properties of the propellant, respectively, but thesernmethods are not fully reliable. The application of structural health monitoring methods tornsolid rocket motors, using embedded sensors, is one approach that is being explored byrnvarious researchers to address many of the above deficiencies of legacy inspection andrnprediction methods. In this paper, we discuss one such method, an active sensingrntechnique that is particularly suited for monitoring the integrity of solid propellant, as itrndoes not require electrical connections. Based on the use of magnetic induction forrnexcitation and an optical fiber Bragg grating sensor to measure deformation, the methodrncan be used to characterize the properties of a material with which it is in contact. In thisrnpaper, we demonstrate its use in demonstrating the viscoelastic properties of an adhesivernand finding the gel point of an adhesive during curing.