Dynamic deployment sensing of thin-shell composite structures with fiber Bragg gratings

Abstract

The efficacy of using Fiber-Bragg Grating (FBG) sensors for the purpose of sensing and characterizing dynamic deployment of bistable composite tape springs is investigated in this paper. Ultra-thin composite structures such as tape springs have seen increased popularity in spacecraft structures due to enabling the precise deployment of flexible solar arrays, sails, reflectors, and antennas. These composite members can elastically transition from either the coiled or folded state to the deployed extended state while possessing superior stiffness, thermal properties, mass efficiency, and compactness when compared to their metal counterparts. Bistability is leveraged to influence more controllable self-deployment and energy efficient stowage, while reducing or eliminating the need for mechanical restraints or motorized deployment. However, a need exists to monitor both the deployment dynamics and overall structural health of the deployed member. Fiber optic sensors such as FBGs have the capability to sense pressure, temperature, and mechanical strain. Due to their relative thinness, low mass, and flexibility, fiber optics may be integrated into these deployable composite structures without significantly interfering with bistability, packaging, or deployability. This paper experimentally demonstrates dynamic strain sensing of deploying bistable composite tape springs via the integration of fiber optics containing FBG sensors. Free deployment from both coiled and folded stowed configurations are characterized.