Apparatus Design and Finite Element Modeling for Controlled‐Speed Nakazima Experiments

ABSTRACT A scaled apparatus was designed for conducting Nakazima stretch‐forming tests with a rotating tool. A 3D finite element model was developed and validated to simulate the modified Nakazima experiments. To reduce the device weight, the 5182‐O aluminum alloy was used as a base material for the blank, die, blank‐holder, and die‐support, while the forming tool and tightening system components were made of high‐hardness armor steel (500 HB). Unlike existing numerical models, all the device components are replicated in the finite element code and are considered deformable. Numerical simulations were conducted to ascertain the equivalent strain and nodal displacement distributions over the tooling components and the principal strain distributions over the sheet. The results showed that the equivalent strains and nodal displacement variations were negligible, thereby demonstrating the resistance and stability of the entire device during the tests. The forming limit curve, major and minor strain variations with dome height to tool diameter ratio, and major strain variation with minor strain were ascertained and compared to the experiments. Good agreement was obtained between the numerical and experimental results, demonstrating the good ability of the developed device to reproduce the modified Nakazima tests.