Parameter optimisation in constitutive equations for hot forging

Various methods for parameter optimisation in constitutive equations applied to the hot deformation of a popular alpha-beta titanium alloy have been examined. The use of direct search and gradient methods are shown to be effective, even with a limited dataset, and reliable confidence limits can be computed in each case. However, a hybrid approach, whereby genetic algorithms are used to find an initial parameter starting point, and then a direct search (simplex) method is applied to obtain a global minimum, is particularly promising. For comparison, an artificial neural network approach, which does not require the use of any constitutive equations, has also been implemented. (c) 2006 Elsevier B.V. All rights reserved.