Load Insensitive Welding of Self Reacting Friction Stir Welding

A new approach to friction stir welding was developed in response to difficulties encountered during the welding of the Ground Test Article (GTA) for NASA’s Orion space vehicle. The approach utilized existing data knowledge and the results of GTA welding to establish a designed experiment. A novel approach was taken to represent and analyze the data, allowing for previously unidentified relations to be seen and characterized.  The effort led to the discovery of weld spaces which were insensitive to large variations of load. This insensitivity was then exploited to generate production weld schedules that reduced weld defects by roughly two orders of magnitude on the Orion Flight Test Article. The successful implementation of this characteristic has led to the development of more robust production weld schedules as well as identify additional areas for process improvement.

The concept of load insensitive welding and the analytical process to identify these weld spaces are currently being adopted by NASA and other companies for implementation in their production welding, as the analysis can be used to identify areas of insensitivity that have yet to be observed.

This paper focuses on the production implementation of load insensitive welding while giving sufficient background to understand how and why this implementation works. Beyond the enormous practical interest of this work to the world of friction stir welding, the underlying creative process, using data analysis, physical reasoning, and production considerations, is of interested to a wider audience.