Formability evaluation using modified cockcroft criterion with strain paths for sheet metal forming

In most situations, the original Cockcroft criterion underestimates material formability in the first quadrant of the forming limit diagram. So far, some modified Cockcroft criteria have been reported for different applications. This presentation focuses on the modified Cockcroft criterion, which takes the strain-path effect into consideration and demonstrates the accuracy of this criterion through the limiting dome height test, the free bulge test, and the biaxial tensile test using a cruciform specimen, respectively. The results showed the modified Cockcroft criterion with the strain path effect to have good agreement with the experimental results.