Verification of Crystallographic Texture Based FLD Predictions for Aluminum Sheet

Determination of forming limit diagrams (FLDs) by experimental methods requires a significant amount of time and expertise in interpretation of data. Their construction can be especially difficult for aluminum alloys due to slightly negative or near zero strain rate sensitivity characteristics which create sharp strain gradients. For this reason a mathematical model which incorporates microstructural attributes, namely crystallographic texture, with a description of strain hardening behavior was developed by Barlat¹ to predict the forming limit strains for a given material. Using Barlat, forming limit diagrams were predicted for various automotive body sheet alloys and verified against experimental data. Excellent correlation was found between the experimental and predicted diagrams. Prediction of limit strains requires approximately one-tenth of the time required for experimental diagrams and eliminates variations associated with experimental determination techniques.