Further Experimental Verification of A Proposed Localized Necking Criterion

An approach to determine the forming limit diagram (FLD) using the concept of inflection point in the major strain rate curve was proposed earlier by the authors. Once the strain history of the element (either grid or speckle) from the localized site is obtained, the localized necking occurs when an inflection point in the major strain rate curve, or, maximum point in the second order of derivative of major strain, (ε̈1)max, is reached. …