1763. The Potential for On-Orbit Manufacture of Large Structures Using the Pultrusion Method

Paper

Abstract

On-orbit manufacture of lightweight, high strength advanced composite structures using the pultrusion process is proposed. This process is adaptable to a zero-gravity environment by using preimpregnated graphite fiber reinforcement systems. The reinforcement material is preimpregnated with a high performance thermoplastic resin at a ground-station, coiled on spools for compact storage, and transported into earth-orbit. A pultrusion machine is installed in the Shuttle cargo bay from which very long lengths of the desired structure is fabricated on-orbit. Potential structural profiles include rods, angles, channels, hat-sections, tubes, honeycomb cored panels, T, H, and I beams. By manufacturing structure on-orbit in continuous lengths, the number of joints would be greatly reduced compared to structure manufactured at a ground-station and assembled in space. Horizontal members are joined to vertical members by ultrasonic or conductive welding techniques. In this way the structural materials can be transported to orbit at high packaging density for fabrication of very low density structure on-orbit. Tailored properties such as stiffness, tensile strength and toughness are controlled by precise fiber orientations and selective combinations of matrix and fiber systems. Illustrations describing the pultruder and its arrangement in the Shuttle bay are presented. Properties of on-orbit fabricated graphite/thermoplastic structures are projected using pultrusion. This fabrication method has the potential for on-orbit manufacture of structural members for space platforms, large space antennas, and long tethers.