ABOUT NECKING DETECTION TO DETERMINE FORMING LIMIT DIAGRAMS FOR MINI STAMPING

13International audienceThis paper develops an extension of the concept of forming limit diagrams for very thin sheets with thickness closed to 0.1 mm. In order to study the mini forming ability of very thin sheet material, a specific drawing tool has been designed and achieved in the laboratory. It has been used in order to characterize the formability of an aluminium rolled and annealed sheet 1050A (99.5%). A system of strain measurement using image analysis by the correlation method is coupled with the mini forming press. Different methods for the determination of the strains at the onset of the necking are proposed