A Comparative Study of Different Necking Criteria for Numerical and Experimental Prediction of FLCs

For sheet metal forming, the determination of the onset of localized necking directly influences the formability evaluation and construction of forming limit curves (FLCs). Several necking criteria in the literature have been proposed and widely used, however, there are some restrictions, e.g., some criteria are suitable for numerical methods but not for the experimental phase. In this study, numerical and experimental procedures are carried out to seek an appropriate necking criterion for the prediction of FLCs. This article begins with the FE modeling of the Marciniak test with ABAQUS. Based on the FE simulation, different necking criteria (global and local ones) are reviewed and analyzed in detail, and the FLCs for a 5086 aluminum sheet are constructed with these criteria. On the other hand, a quasi-static experimental Marciniak test is carried out to study the formability for this given sheet. With a chosen necking criterion, the limit strains are experimentally determined. The comparison between experimental and numerical results shows that the chosen necking criterion could be effective to numerically and experimentally evaluate the global formability of this aluminum alloy on the wide range of strain states.