A Mechanistic Study of the Friction Stir Welding Process
- Paper number
IAC-06-C2.8.12
- Author
Mr. Reginald Crawford, Vanderbilt University, GCRC, United States
- Coauthor
Dr. George E. Cook, United States
- Coauthor
Dr. Alvin M. Strauss, United States
- Year
2006
- Abstract
The NASA Marshall Space Flight Center (MSFC) currently uses the friction stir welding process to construct the external fuel tanks for its space shuttle booster rockets, as well as conducting research to improve process utility for application for in-space repair of mechanical structures. This research is geared towards assisting the MFSC Materials Processes and Manufacturing Department in determining optimal weld parameters for expansion of the process from low melting aluminum alloys to higher melting copper alloys. Vanderbilt researchers have sought to quantify the relationship between axial force (Fz), rotational speed, travel speed, and other process parameters for friction stir welding (FSW). Experimental data for Al 6061-T6 welded at high rotational (1500-20000 rpm) and travel speeds ranging from 45-200 ipm will be presented. The results will be discussed and will be compared to three dimensional Couette and Visco-Plastic fluid flow models implemented using the computational fluid dynamics package FLUENT. The forces and torques associated with friction stir welding will be discussed relative to enhancing the feasibility for robotic implementation of FSW. Recent advances in guidelines for control schemes for robotic FSW will be discussed relative to FSW process parameters. The major requirements for a robot capable of FSW is two fold; simple positioning of the weld tool and providing the axial force (Fz) necessary for FSW, which have been shown to be quite substantial. Current FSW applications employ heavy duty machinery. The rigidity and precision of the machine tool allows the axial force to be maintained over the extent of the weld, however they are only capable of following two-dimensional contours. With a robotic implementation capable of following three dimensional contours, the contact forces associated with FSW using current process parameters, leads to compliance of the manipulator. For completeness, implementation of force feedback control (an area of limited exploration) is discussed as well as optimum parameters for robotic FSW.
- Abstract document
- Manuscript document
IAC-06-C2.8.12.pdf (🔒 authorized access only).
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