In flatable/rigidizable structures have shown promise for use in space, due to their intherent light weight and low packaged volume. Under this program, complex joints of inflatable/rigidizable tube members were developed. Two 150cm-long modular trusses have been designed, built and tested. Each truss consists of separate inflatable/rigidizable legs, joined together at the intersection points with cast aluminum manifolds. A thin plastic layer comprises the pressure barrier inside each tubular leg. The main tubular leg composite consists of a fabric impregnated with a water-soluble resin, which rigidizes when dehydrated by evaporation of the water, thus giving the composite its strength. One advantage of using solvent-based systems is their reversibility, i.e., the rigidized composite can be softened and re-rigidized repeatedly by controlling its water content. Outside of the composite layer is an outer enclosure which meters the evaporation of the water solvent during rigidization and also prevents blocking of the composite during packaging. The testing program consisted of packaging, thermal cycling, vibration, deployment and rigidization in ambient and vacuum conditions, bending/compression tests, and determination of natural frequency. The effects of wall thickness, diameter and lateral length of the modular cylinder and composite stiffness on the strength of the truss were determined by a finite element ananlysis model (FEM).
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