Developing Technologies and Techniques for Additive Manufacturing of Spacesuit Bearings and Seals
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Human exploration beyond low Earth orbit will require increasing self-sufficiency in light of the logistics support challenge. One critical area is in spacesuit maintenance, parts replacement, and eventually in-situ manufacturing. An ongoing project at the University of Maryland (UMd) is exploring additive manufacturing (AM) for space suits, both “hard suits” entirely fabricated from feed stock, and “hard” elements of conventional hybrid suits. The current technology development focus is on the integral structural elements of bearings, and seals, and interfaces to the suit envelope. Prior work investigated the feasibility of “printing” full bearings, and led to the realization that current AM techniques are of insufficient precision to allow the fabrication of the bearing balls directly. Complete bearings were assessed for joint friction under varying loads, and tested to destruction to verify the ability to meet both pressurization and human loads with adequate factors of safety. Seals were fabricated of elastomeric 3D printed materials and tested for sealing performance and friction. Complete suit bearing prototypes consisting of both AM bearings and seals were fabricated and subjected to hydrostatic pneumatic load tests, as well as tested in the UMd glove box and cycled to determine operating lifetime. Based on these results, the best performing design that met all requirements was selected for the fabrication and test of a complete AX-5-type four-roll elbow module, which was integrated to soft goods upper and lower arm segments and terminated with a glove box sealed bearing on the proximal end and a standard glove disconnect on the distal end. This arm segment was then used for human factors evaluations in the UMd glovebox, including quantifying dexterity via a Fitts’ law protocol .