Cylindrical Fold Study Of A Large In-Space Deployable Membrane Parabolic Reflector

Membrane parabolic reflector, in this paper, is a kind of in-space inflatable/deployable membrane structures, which has significant small packed-volume-to-deployed-size ratio and promises to dramatically reduce the cost of launching and manufacture. However, many challenges must be overcome before such an inflatable structure can be applied in space environment. Fold technique act a key role in the research and development of in-space deployable membrane parabolic reflector.An innovative fold pattern is proposed to fold large diameter membrane parabolic reflector to a cylindrical state to store, which called cylindrical fold. By using cylindrical fold, the large diameter parabolic reflector can be fold into a cylinder, and have quite good deployment control ability.The fold model is developed to define the relationship between the fold line and required fold size. The topological relation from plane to parabolic is also present to help determine the position of fold line on parabolic surface of the reflector. The fold lines are so regular that can be divided into four groups: radius fold line, regular polygon fold line, parallel fold line, vertical fold line, which are closely related to each other.Fold and deployment tests of membrane parabolic reflector models are done to demonstrate the feasibility and efficacy of the fold cylindrical fold. All deployment tests were success, and fold tests show that the cylindrical fold is feasible and have good fold ratio.To explain the problem in the tests, mechanical problems during fold process are also investigated in this paper, particular attention is put on the crease and bend distortion in the film which all caused by fold. The strain and stress in different stages are investigated to find how to reduce the influence by crease. The model of bend distortion during deployment is introduced, which can describe the relationship between the deformation and fold parameters.