Development of integrated decision support system for creep age forming

The Creep Age Forming process involves the creation of a primary elastic stress field within a component, via clamping to an overformed, theoretically rigid tool surface. The component / tool assembly is then exposed to a thermal cycle appropriate to the development of mechanical properties within the parent alloy system of the component. During this cycle, the applied stress partially relaxes as a by-product of precipitation hardening. As a result, once the constraints holding the component in contact with the tool are released, the remaining locked-in stress is released allowing the component to springback to a final shape which, with the fortune of good tooling design, will be the final required shape. The main feature of the Creep Age Forming process is the large amount of elastic springback (>70%), making the design of tool surface profiles (often incorporating significant double curvature) difficult, time consuming and costly (current methods of tool surface definition rely on a combination of empirical testing coupled with intelligent trail and error). This level of uncertainty has prevented the full exploitation of the process within design and manufacture. In this paper, the development and application of an integrated decision support system is discussed, elements of which include a customised user interface to a proprietary Finite Element package, allowing manufacturability assessment of competing product designs and the determination of process and hardware requirements. Additionally the application of an iterative optimisation scheme for tool surface profile generation will be presented, together with the results of large-scale analysis on aircraft structural components.