Tôles pour emboutissage caractérisation par les courbes limites en contraintes

Determination of the forming limit stress diagram for anisotropic steel sheets

¹ Arraché temporaire d'enseignement et de recherche au laboratoire de mécanique des solides de l'INSA-Lyon
² Professeur, Directeur du Laboratoire de mécanique des solides de l'INSA-Lyon.

Abstract

In this work, we propose a calculation method based on Hill’s yield criterion to determine the forming limit stress states for anisotropic sheets.

For three types of steel, at first we have determined experimently the forming limit diagrams, figured in strain plane, for various strain path shapes. From these diagrams, we can calculate the limit stress states then we show that, for all strain path shapes, this stress states are on the same limit curve, which allow permit us to tell that this limit curves, figured in stress plane, are independant of the strain path shape, which is particularly interesting for necking predictions.

In fact, knowing the limit curve in stresses, a caracteristic of material, we can make the opposite calculation and determine the necking appearance for any strain path shape. The results obtained match with the experimental results.