Deployment of Bistable Self-Deployable Tape Spring Booms Using a Gravity Offloading System

Bistable tape springs are suitable as deployable structures thanks to their high packaging ratio, self-deployment ability, low cost, light weight, and stiffness. A deployable booms assembly composed of four 1-m long bistable glass fiber tape springs was designed for the electromagnetically clean 3U CubeSat Small Explorer for Advanced Missions (SEAM). The aim of the present study was to investigate the deployment dynamics and reliability of the SEAM boom design after long-term stowage using onground experiments and simulations. A gravity offloading system (GOLS) was built and used for the onground deployment experiments. Two booms assemblies were produced and tested: a prototype and an engineering qualification model (EQM). The prototype assembly was deployed in a GOLS with small height, whereas the EQM was deployed in a GOLS with tall height to minimize the effects of the GOLS. A simple analytical model was developed to predict the deployment dynamics and to assess the effects of the GOLS and the combined effects of friction, viscoelastic relaxation, and other factors that act to decrease the deployment force. Experiments and simulations of the deployment dynamics indicate significant viscoelastic energy relaxation phenomena, which depend on the coiled radius and stowage time. In combination with friction effects, these viscoelastic effects decreased the deployment speed and the end-of-deployment shock vibrations.