Patent ID: 7191032

Claim:
A method executed by a computer system as part of a computer-implemented program for optimizing pressure-time history for a process for forming a workpiece from an initial hollow metal preform into a hollow metal article within a die by subjecting the workpiece to net internal fluid pressure such that the workpiece expands into contact with an article-shape-defining wall of the die, while avoiding failure of the workpiece, comprising the steps of (a) selecting a set of process parameters including temperature and preform material properties and dimensions; (b) determining, from said set of parameters, at least one failure criterion limiting pressure-time conditions to which the workpiece may be subjected without failure; and (c) iteratively performing finite element analyses on the workpiece, based on the selected set of parameters and the determined failure criterion, at each of a plurality of different values of pressure-time conditions (P, t), to determine pressure-time boundary conditions (P b , t b ) for the process, wherein each value of pressure-time conditions comprises a value of net internal fluid pressure (P) and a time interval (t) over which the last-mentioned value of net internal fluid pressure is applied to the workpiece.