Description: This Phase I program addresses the NASA needs for Technical Area TA12 which provides technologies supporting advanced manufacturing, structures, and materials. In this program, ultrasonic thermometry methods will be adapted to enable real time, temperature measurements during a friction stir weld, FSW. While FSW it has been successfully used at NASA-MSFC in the robust joining of thinner panels of aluminum alloys, the production of high quality welded joints in thicker panels or higher melting temperature materials remains challenging. Knowing and controlling the temperature is essential to optimize the process to ensure the production of repeatable, robust components. Using sensors attached to the stir weld tool, precise time-of-flight (ToF) measurements of ultrasound propagating through the weld zone will be used to estimate temperature. This temperature measurement made in the weld zone is non-intrusive and does not influence the thermal transport. Temperature data can be obtained at data rates as high as 1 kHz with the precision of a few degrees Centigrade. Once this “smart” stir weld tool temperature sensor is demonstrated, this technique can be incorporated into a control strategy and readily migrated to any of the FSW variations under development at the NASA-MSFC.

Benefits: The “smart” friction weld stir tool temperature concept demonstrated in this Phase I program addresses the needs of NASA's advanced manufacturing, structures, and materials road map. This temperature measurement technology is generally applicable to all solid state welding processes such as friction stir, thermal stir, and ultrasonic stir welding. Applications include a wide range of NASA programs that require high performance, low cost, innovative, propulsion systems and spacecraft components.

The “smart” stir weld tool with integrated temperature sensor is applicable to all solid state joining processing methods. Commercial companies pursuing FSW technologies include: Boeing, Airbus, Hayes wheels, Williams International, ULA, and Lockheed-Martin. This technology is also of interest to FSW equipment manufacturers/service providers e.g. General Tool Co., Concurrent Technologies Corporation, The Welding Institute, Manufacturing Technology, Inc., and Edison Welding Institute.