FLSD as a good choice in sheet forming of AHSS

Abstract

The automotive industry has increased significantly the use of advanced high strength steels (AHSS) in many structural components, with the aim to reduce weight and also to increase safety. The high resistance of these steels is accompanied by a decrease in formability, which makes simulation a requirement to adequately foresee the formability of a particular stretch formed component. This work shows that Abaqus can be used in the cold stamping calculations, by mainly estimating the occurrence of rupture and necking during forming. Formability studies usually use forming limit diagrams (FLD), based on stains, as a failure criterion, but this approach is not effective when working with AHSS. This work proposes the use a forming limit stress Diagram (FLSD) based on the main stresses acting on the material. A brief explanation of how to obtain these FLSD curves is presented, where ABAQUS also plays an important role. Finally, comparisons using simulations from AUTOFORM and real parts are shown and discussed. The comparison was performed using Abaqus CAE and Viewer as post-processing tools. A script allows reproducing the mesh generated by AUTOFORM, map the data and postprocess with the FLSD criterion. All the methodology presented uses ABAQUS as an integral tool, from the characterization of the material to the analysis of complex parts.