Hot Vacuum Creep Forming of Scale Shuttle External Tank Dome Caps

Abstract : This program covered selected tasks incidental to conducting a feasibility study for forming the shuttle external tank dome caps by hot vacuum creep forming. It was necessary to conduct this study on a sub-scale configuration due to limited material availability; this limitation concerned both sheet size and quantity. The study was limited to forming 2219-T37 aluminum at an elevated temperature equivalent to the artificial aging time and temperature used to produce the T87 condition while achieving MIL-H8K-5 properties of 2219-T87 aluminum alloy material. The feasibility study was conducted in two phases; the design and build of a sub-scale hot vacuum creep forming (HVCF) die and the forming evaluation of various cap configurations. The contour was constant in all evaluations. Conclusion summary is that this particular configuration is too severe for the limited forming force available by HVCP.