Cable-Stiffened Pantographic Deployable Structures Part 2: Mesh Reflector

The general concept of deployable structures based on pantographs that are deployed and stiffened by means of cables is applied to the design of the support structure for a large mesh reflector. The two main components of this structure are a cable-stiffened pantographic ring that deploys and pretensions a cable network that, in turn, provides a series of stiff, geometrically accurate support points to which a reflective wire mesh or flexible membrane would be connected. The pantographic ring is a highly redundant structure with an internal mechanism that permits synchronous deployment without any strain in the rods. The geometric conditions that have to be satisfied in order for an n-sided ring to fold without any strain are investigated, including the effects of joint size. An experimental model has been designed and tested. In the folded configuration, it has a diameter of 0.6 m and height of 1.2 m; in the deployed configuration, it has a diameter of 3.5 m. Stiffness and deployment tests on this model have shown its behavior to be linear and the maximum shape error to be ±0.3 mm.