INTRODUCTION

The previous chapter was concerned with producing a correct statement of the elastic–plastic element stiffness equations and their assembly into the global stiffness equations. As they stand, these expressions simply describe how the forces applied to the nodes of a discretised model of the workpiece change as those nodes are displaced by small amounts from their starting positions. It is now necessary to consider how these equations can be used within an FE analysis for the study of practical metalforming operations.

PERFORMING AN FE ANALYSIS – AN OVERVIEW

It is instructive to consider the entire process of performing an FE analysis of a metalforming operation (figure 6.1). Of the four main parts of this process, the FE calculation will always be undertaken by a computer program: the description of the metalforming operation and the pre-processing and post-processing stages may be integrated into the FE package, may be separate computer programs, or even be performed by hand.

The starting point in any such analysis is the metalforming operation itself. The first stage in the analysis is therefore concerned with obtaining a complete description of the operation in geometric or numerical form. This description will include information about the initial geometry of the workpiece, the shape of the dies and how the relative position and orientation of the dies and workpiece change during the deformation, the previous history of the workpiece and the dies, and the particular metal being formed.