In the present work forward projection is proposed as a new approach to determine the preform shape in rib-web type forging. In the forward projection technique an optimal billet is determined by applying some mathematical relationship between geometrical trials in the initial billet shape and the final products. In forward projection a volume difference between the desired product shape and the final computed shape obtained by the rigid-plastic finite element method is used as a measure of incomplete filling of working material in the die. At first linear inter-/extrapolation is employed to find a proper trial shape for the initial billet and the method is successfully applied to some cases of different aspect ratios of the initial billet. However, when the initial guesses are not successfully near the optimal value linear inter-/extrapolation does not render complete die filling.
For more general application, a fuzzy system is used in the forward project technique in order to determine the initial billet shape for rib-web type forging. In the forging simulation, the rigid-plastic finite element method is used in connection with the modular remeshing technique. It has been thus shown that the fuzzy system is more reliable for the preform design in the rib-web type forging process.