The aim of this research was to introduce a simulation-based approach for determination of the Forming limit curve (FLC) in two-layer metallic sheets. In this study, the FLC of Aluminum-1100/Copper-C10100 two layer sheets were obtained through numerical simulations and experimental investigations. In order to construct the FLC, two different criterions including the acceleration (i.e., the 2 nd order of derivatives) of equivalent plastic strain and major strain were applied to obtain the onset of necking in the materials. Based on these methods, the localized necking would be started when the acceleration of the equivalent plastic strain or the major strain got its maximum value. To verify the numerical predictions, the experimental works were accomplished on the Aluminum-1100/Copper-C10100 two-layer sheets and a good agreement between the proposed methods and experimental works was observed.

In this paper, the formability of two-layer (aluminum-st12 steel) sheets in the deep drawing process was investigated through numerical simulations and experiments. The purpose of this research was to obtain more formability in deep drawing process. The limit drawing ratio (LDR) was obtained in deep drawing of two-layer metallic sheets, with aluminum inner layer which was in contact with the punch and steel outer layer which was in contact with the die. Finite element simulations were performed to study the effect of parameters such as the thickness of each layer, value of die arc radius, friction coefficient between blank and punch, friction coefficient between blank and die, and lay-up on the LDR. Experiments were conducted to verify the finite element simulations. The results indicated that the LDR was dependent on the mentioned parameters, so the LDR and as a result the two-layer metallic sheet formability could be increased by improvement of these parameters in deep drawing process.

The aim of this research was to introduce a computational approach for prediction of the forming limit diagram of Al-Cu two-layer metallic sheets. The computational approach was based on the modified Marciniak and Kuczynski theory. In this study, the forming limit diagrams of aluminum-copper two-layer metallic sheets were obtained through the modified Marciniak and Kuczynski theory and experimental investigations. In the present modified Marciniak and Kuczynski theory, there existed four nonlinear equations which were solved simultaneously. The Quasi-Newton Method was applied for a solution to the system of equations. To verify the theoretical predictions, the experimental works were accomplished on the Al-Cu two-layer metallic sheets and a good agreement between the proposed method and experimental works was observed.

Forming limit curve (FLC) is a suitable method for determining the metallic sheets formability. The purpose of the present research is to expose a simulation-based approach to predict the FLC in two-layer metallic sheets. In this paper, the formability of two-layer (AA3004-ST12) metallic sheets, with an aluminum inner layer (in contact with the punch) and a steel outer layer (in contact with the die) was numerically investigated. Two distinct criteria, including the acceleration (i.e. the second time derivatives) of thickness, and major strain extracted from the strain history information of finite element software, were applied to determine the commencement of local necking in FLCs. It shows that the localized necking starts when the acceleration of the thickness or major strain, is maximized. The published experimental results for AA3004/ST12 two-layer metallic sheets were employed in order to evaluate the simulation results. It is shown that the presented methods are noticeably aligned with the published experimental data. By the grace of present methods, the effects of some process parameters on the FLC have been investigated. It is shown that process parameters such as thickness and lay-up of each layer will have significant influences on FLC of two-layer metallic sheets.