Thermoplastic matrix composites for Space Solar Power Truss (SSP)
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Thermoplastic matrix composites for SPACE SOLAR POWER TRUSS (SSP) Hao Zhanga, Koorosh Guidaneanb, Steven Nutta* a
MC. Gill Composites Center, University of Southern California, 3651 Watt Way, Los Angeles, CA 90089-0241
b
L’Garde Inc., 15181 Woodlawn Av., Tustin, CA 92780
ABSTRACT: Thermoplastic matrix composites with a low glass transition temperature (Tg) have been developed for the Space Solar Power Truss (SSP). In this application, the truss is folded and packaged for launch, then expanded and deployed in space using a heat source. The present paper describes a resin film infusion process (RFI) used to fabricate laboratory-scale laminate tubes consisting of polyurethane and plain weave carbon fabrics. Subscale (1:5) sample tubes were formed to approximate the real tubes. The performance of the folded and unfolded tubes was measured under compression loading and compared with as-fabricated tubes at 25 and -75°C. Results show that elastic modulus was restored and even increased after bending. Stitched samples were also examined to evaluate the potential for reducing delamination at folds. Keywords: Sub-Tg, Thermoplastic matrix composites, compressive properties, RFI, Folding, stitching
INTRODUCTION Most of the widely applied thermoplastic polymers have found commodity applications that typically have modest service temperature requirements. Some distinct polymers have been developed to satisfy the engineering applications at higher temperature caused by aerodynamic friction during high-speed flight [1]. However, few efforts have invested in developing sub-Tg inflatable rigidizable thermoplastic composites, which works at low temperature in space. Inflatable space structures feature high strength-to-weight ratio and ease of packaging compared with mechanically deployable structures. L’Garde Inc. has been investigating and developing space rigidizable hardware for over a decade. They have developed and evaluated several kinds of inflatable rigidizable materials and fabrication methods, including aluminum laminates, Gel/water-based composites, UV curable composites and thermoset composites. Of these approaches, sub-Tg rigidization has great potential in terms of overall performance and compatibility with complex structural designs [2,3]. Among the most important attributes of these materials are the unlimited shelf life, the ability to test structures on the ground, and the modest power requirement for deployment after launching (unlike thermoset or UV-based systems, which require further treatment). Finally, because thermoplastic polymers can be softened and re-shaped by heating, repeated ground tests can be conducted. A problem for many fiber-reinforced polymer laminates used in space truss structures is the high patulous volume compared with the actual material volume. This can result in the relatively high ground packaging volume, which greatly increases the cost. In contrast, inflatable * To whom correspondence should be addressed
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self-rigidizable composites can be folded on the ground, e
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