Stepwise deployments of membrane structure with rolled-up CFRP bi-Convex booms

Stepwise deployments of a membrane structure with rolled-up booms have been investigated. The boom consists of two bi-convex tapes covered by a braid sleeve. The boom can be smoothly rolled up and unrolled by elastic deformation. In this paper, new lightweight booms consists of tri-axial woven fabric CFRP convex tapes with 800 millimeter long are introduced to reduce the weight and to enlarge the structure. First of all, in order to study the mechanical properties of the boom, three point bending test and vibration test of are carried out. Then deployment experiments of four booms rolled-up around a central hub are conducted to confirm that the booms can be fully deployed under gravity. Subsequently, deployment experiments of the booms with a square membrane folded by the modified spiral folding are conducted. To prevent lateral buckling of the booms due to the weight of the membrane, a simple gravity compensation method using suspension strings is devised. Deployment experiments of several deployment patterns are successfully performed and the effects of the stepwise deployments are clearly demonstrated. Finally, numerical model of the structure is created by employing the multiple particle approximation method and stepwise deployment simulations are conducted.