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Bi-stable tape springs are ultra-thin fiber-reinforced polymers composites, which could self-deploy through releasing stored strain energy. Strain energy relaxation is observed after long-term stowage of bi-stable tape springs due to viscoelastic effects and the tape springs might lose their self-deployment abilities. In order to mitigate the viscoelastic effects and thus ensure self-deployment, different tape springs were designed, manufactured and tested. Deployment experiments show that a 4-layer, [-45/0/90/45], plain weave glass fiber tape spring has ahigh capability to mitigate the strain energy relaxation effects to ensure self-deployment after long-term stowage in a coiled configuration. The two inner layers increase the deployment force and the outer layers are used to generate the bi-stability. The presented 4-layer tape spring can self-deploy after more than 6 months of stowage at room temperature. A numerical model was used to assess the long-term stowage effects on the deployment capability of bi-stable tape springs. The experiments and modeling results show that the viscoelastic strain energy relaxationstarts after only a few minutes after coiling. The relaxation shear stiffness decreases as the shear strain increases and is further reduced by strain energy relaxation when a constant shear strain is loaded. The numerical model and experiments could be applied in design to predict the deployment force of other types of tape springs with viscoelastic and friction effects included., QC 20170508, SEAM

The rapidly growing use of nano- and pico-satellites for space missions requires de-ployable systems to be highly storable yet large and with adequate mechanical properties when deployed. This paper focuses on the modeling and simulation of a meter-class passively deployable boom, based on the self-contained linear meter-class deployable(SIMPLE) boom by Thomas W. Murphey, exploiting the bi-stable nature of compositeshells. Experimental tests were carried on a boom prototype suspended in a gravityo-offloading system. The strain energy level, deployment time and spacecraft displacements calculated from the finite element method agree well with analytical analyses, confirming the theoretical accuracy of the finite element method. Since friction and strain energy relaxation were not accurately included in the model, the finite element simulations predict deployment times up to five times shorter than those of the gravity off-loaded boom experiments. The quick deployment and violent end-of-deployment shock create boom deployment dynamics which are not seen in the experiments., QC 20170509