Investigation of Portevin-Le Châtelier effect during Erichsen test

Abstract

This study deals with the occurrence and numerical prediction of Portevin-Le Châtelier (PLC) instabilities during a forming process at room temperature. In a first part, the mechanical behavior of an aluminium alloy (5000 series) thin sheet is investigated in tension and simple shear under quasi-static conditions and at room temperature. As PLC effect takes place, jerky flow and bands of localised deformation, observed by digital image correlation, are clearly evidenced. A forming process, consisting of the mechanical bulging of a blank clamped between a die and a blank-holder with a hemispherical punch (Erichsen test), is then performed, using in-situ observation of the localised deformation bands and their propagation. In a second part, material parameters of McCormick’s model are identified considering both tensile and simple shear tests. Moreover, Hill’48 yield criterion is used to represent the material anisotropy. Finally, the numerical simulation of the Erichsen test is performed with McCormick’s model and the comparison of the load and band propagation with experiments shows a good prediction of plastic instabilities during a forming test.