Deflection of multicellular inflatable tubes for redundant space structures

A new concept of redundant space structures using multicellular inflatable elements is proposed, and the results of basic analyses on simple multicellular models are reported. Much effort has been devoted to methods for sufficiently hardening the inflatable elements in space to tolerate damage sustained from space debris, especially with respect to rigidization of a membrane; however, if the structures are redundant, they do not need to be as stiff and strong as those without redundancy. Deflections of two kinds of multicellular cantilever inflatable tubes are numerically investigated. First, nonrigidized tubes are analyzed by the modified Euler-Bernoulli beam theory. Second, rigidized tubes with slackening effects of the membrane are simulated using the modified nonlinear finite element method. The results show that multicellular tubes can be redundant against problems with pressurization and can be as stiff and as strong as monocellular models with less internal gas. In the multicellular rigidized inflatable tubes, maintaining a small amount of internal pressure is quite effective to prevent the deformation of the cross section, which causes a drop in stiffness and strength. Therefore, adopting a redundant system is effective both for rigidized and nonrigidized inflatable elements.