Sharif Digital Repository

Forming Limit Diagrams are useful tools for evaluation of formability in the sheet metals. In this paper the effects of yield criteria on predictions of the right and left-hand sides of forming limit diagrams (FLDs) are investigated. In prediction of FLD, Hosford 1979, "Karafillis-Boyce" (K-B) and BBC2000 anisotropy yield functions have been applied. Whereas the prediction of FLD is based on the "Marciniak and Kuczynski" model, thus a numerical approach using the Newton-Raphson method has been used. Forming Limit Diagrams have been obtained for Al 6111-T4 and AA5XXX alloys and results have been compared with published experimental data. Results indicate that predictions of FLD are very... 

Forming limit diagram is often used as a criterion to predict necking initiation in sheet metal forming processes. In this study, the forming limit diagram was obtained through the inclusion of the Marciniak–Kaczynski model in the Nakazima out-of-plane test finite element model and also a flat model. The effect of bending on the forming limit diagram was investigated numerically and experimentally. Data required for this simulation were determined through a simple tension test in three directions. After comparing the results of the flat and Nakazima finite element models with the experimental results, the forming limit diagram computed by the Nakazima finite element model was more convenient...