Numerical determination of micro-forming limit diagrams: introduction of the effect of grain size heterogeneity

Abstract

This paper presents the determination of virtual micro-forming limit diagrams by a behaviour law adapted to thin materials introducing the effect of microstructure heterogeneity. The observed size effect, i.e. the decrease in flow stress when the grain size increased, was modelled by a specific phenomenological behaviour law. A reduced numerical simulation by a finite element method rendered it possible to carry out very fast simulations of the different modes of deformation and to determine the virtual micro-forming limit diagrams from the onset of necking. This methodology was compared with experimental results on aluminium 1050A (99.5%) of thickness 0.2 mm. The comparison of the experimental and numerical data demonstrated good agreement between the real and virtual results obtained by such a methodology.