Prediction of Forming Limits of Sheet Steels in Automobile Industries

The forming limit diagram, which is widely used in the sheet metal stamping industry in developing new forming operations, is predicted from the plastic instability criterion proposed by Jun. Predicted forming limits are compared with the experimental data for several sheet steels that are important in the automotive industry. It is found that the predicted forming limits for the steels agree with the experimental results with reasonable accuracy in initial proportional loading and complex loading paths.