Robotic-Assisted, Solid-State Material Joining Using Friction Stir Welding

NASA’s future planetary-based exploration missions will require human habitats as well as material/product development in order to subsist on the resources of the planets. To minimize crew time and cost for the construction of planet-based infrastructures (such as habitats, workshops, and other facilities) and to assure safety during operation, an optimal approach would be to transport only necessary raw materials/components from Earth to the planets and to use fully automated or robotic-assisted manufacturing systems to fabricate and assemble the structures in-situ. Clearly, development of innovative in-space/in-situ fabrication and repair capabilities is crucial to NASA's long-term human exploration and the development of space and planets.

WCSAR, leading a team composed of researchers from the Departments of Mechanical Engineering and Material Science, is developing state-of-the-art, robotic-assisted portable friction stir welding (FSW) tools/machines for space-based applications. FSW is a relatively new process that joins metallic materials together in a solid state (namely, without melting the materials). This process forces a uniquely-designed rotating tool to penetrate to-be-joined workpieces, to mix or stir materials together without localized melting, and to locally forge the materials in the joining region. The evident advantages of this process over conventional fusion or arc welding are: (a) no excessive heat is generated, (b) no toxic off-gases are generated, and (c) no material incompatibility is involved. This results in a joint without many of the defects found in conventional welding such as cracks, porosity, thermal distortion, and high residual stress. Most significantly, it enables the joining of all aluminum alloys as well as other alloy materials, which would be otherwise very difficult, if not impossible, with traditional welding. Robotic-control of the FSW process for space-based applications provides precise control of involved forces and motions to assure the consistency and quality of the process, minimizes crew time needed for performing the FSW tasks, and assures safety during the fabrication, assembly, and repair of space-/planet-based infrastructures, which is always of paramount concern for any exploration mission.

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For more information, please contact:

Dr. Weijia Zhou Tel. 608-262-5526