Design And Deployment Analysis Of Flat Flexible Deployable Structure

Flexible structure plays a very important role in aerospace industry as satellite antenna, lens hood, interplanetary vehicle battery array or large-scale solar sail. As the consideration of space saving problem, flexible structure needs to be folded. The process of deployment is complicated and crucial for the performance of space structures so that the analysis and prediction of deployment are the key part of space tasks. For this reason, this paper brought up two methods for design, multi-element design method and multi-stage deployment method. And a large rectangular thin film reflectarray antenna and a two-stage deployable solar sail were designed using these two method. To predict the deployment process, a improved spring-mass model was put forward which considering the crease stiffness. And a Fortran grogram was made up using this model to simulate the deployment of the two-stage solar sail. Also a model is made up and a simple experiment was put to prove the two-stage deployment characteristic.This paper firstly reviewed the research status of flat flexible deployment structures and gave conclusions of the structure types, deployment types and analysis modeling methods of larger-scale solar sails. Then the multi-element design method and multi-stage deployment method in view of structure element decomposition and comprehension was discussed. Moreover, a new deployment type, spinning deployment structures, was discussed from scheme, composition, material, design method, analysis modeling and deployment characteristics aspects.The reason for winding in deployment was discussed and the anti-winding rules was put forward for winding problem of flexible structures in deployment process. This rules brought up two design ideas, one for multi-element structure design method, the other for multi-stage deployment design method. For multi-element design method, the structure scheme design of a large rectangular thin film reflectarray antenna was brought up as a case study from engineering background. Four kinds of improved schemes of rectangular thin film reflectarray antennas composed of inflatable tubes, cables and membrane were discussed and analyzed.For multi-staged deployment method, taking a large-scale solar sail as an example, a two-stage rolling folding method was put forward and two-stage spinning solar sail and two-stage inflated frame solar sail were so that discussed. For different shapes of membrane the two-stage deployment could be performed through this folding pattern. Also, the key technology and theoretical basis of first stage deployment both in inflating and spinning were introduced.A general folding method and topology relationship for deployment analysis of the second stage was brought up. The characteristics of creases during deployment were studied and a simple analysis model was discussed based on spring-mass model so that flexible structures were described by particles and springs which connect them. Crease stiffness and the full-deploy shape norm were studied. The motion track of perfect deployment was deduced.A case of square membrane deployment in unperfected folding pattern both in multi-stretch station and spinning station were simulated though a FORTRAN program using crease-mass model in multi modules. The deployment matches well with the perfect deployment track. The effect of crease stiffness was discussed about force and deformation.A small model was made for the spinning experiment which prove the two-stage deployment characteristic.Finally, the applicability of the crease-mass model were discussed. Some suggestions were brought up for analyzing and simulating flexible structures which broadened up the application range of spring-mass model.