The use of the finite-element method to design an optimized tool for the plain-strain punch stretching test

The tool geometry of the plane-strain punch stretching (PSS) test was optimized by computer simulation to assure test reliability. A three-dimensional, finite-element method (FEM) was used to optimize the three design variables: the punch length, punch crown, and punch corner radius. Experiments confirmed the plane-strain condition predicted by experiment. From this simulative study, we can conclude that the optimized punch shape of the PSS test, with ellipsoidal shape, exhibits stable performance when evaluating the stamping formability of sheet materials. Clearly, the optimized punch geometry with a punch crown of 3 mm, punch corner radius of 6 mm, and punch length of 72 mm shows better reliability compared with that of the original PSS test.