Friction Stir Welded Aluminum Machining Preforms [ FSWAMP ]

Applied Optimization, Inc., in working with EWI, Inc. and Boeing Phantom Works, proposes to demonstrate feasibility of using friction stir welding [FSW] for the manufacturing of large Al 7050-T7451 preforms in four steps as follows. In the first step, representative preform will be generated from the finish shape of a large load-bearing airframe component of current interest to the USAF. The preform geometry will be such that it can be built up from extruded cross-sections and individual forgings. In the second step, the FSW joints configurations will be determined. These configurations will be self-interlocking in case of joints that are subjected to severe in-service loading. These joints will be determined by performing a stress analysis on the airframe component. A preform assembly sequence comprising the fixtures and its presentation to the FSW tool will be developed in CAD software. In the third step, representative FSW joints will be fabricated on sub-element coupons. The coupons will be heat treated and tested under static and fatigue loading in order to develop a Procedure Certification Document [PCD] and to characterize the FSW joint efficiency. In the fourth step, the material properties from the PCD will be used to perform a stress analysis of the airframe component to check its service performance, and to know if the FSW joint efficiency necessitates any local redesign of the component. This data will be utilized to estimate the cost viability of FSW versus direct machining for block hog-out.