Influence of strain hardening on forces and contact pressure distributions in forging processes

Purpose: The main aim of this paper is to analyze forging processes by means of the Finite Element Method (FEM) and the comparison of results with analytical methods that have been traditionally used: the Slab Method (SM) and the Homogeneous Deformation Method (HDM). Design/methodology/approach: Both analytical methods are easier to apply than FEM but they provide less accurate results than the numerical technique. Phenomena such as the strain hardening can be easily incorporated into the Finite Element model so the influence of this factor on variables such as contact pressure distributions and platen forces can be studied. Findings: Forces analysis shows that they are higher when strain hardening is considered. The curves of the FEM and of the SM are practically identical for the rigid perfectly plastic material. However, differences between FEM and SM are obtained for the strain hardened material. The analysis of contact pressures demonstrates that maximum pressures are always found at the center of the workpiece by SM. Otherwise, maximum pressures by FEM are located near the free surface for the lowest reductions. Research limitations/implications: This work is a preliminary study of the influence of strain hardening on these variables. The Finite Element model that has been developed can be improved by incorporating factors such as thermal effects or models of material more complex. Practical implications: The influence of many variables on forging process efficiency can be analysed by numerical techniques in a simple manner by means of few changes in the model. Originality/value: Although several studies about analysis of forging processes by FEM can be found in the literature it is difficult to find a comparison between analytical and numerical results.