| To effectively model sheet metal forming processes, an existing hybrid/mixed shell element is extended to account for large plastic strain effects, for which particular attention is paid to the use of polar decomposition, Truesdell objective stress rate in the particular context of a hybrid/mixed formulation. A group of numerical examples exhibiting finite/large plastic strains which are rarely addressed in the literature are presented.; To this end, a robust elasto-plastic constitutive model, which includes a fully implicit radial return integration scheme and the associated consistent tangent stiffness, is developed with a special reference to the generalized plane stress conditions.; In order to improve the global solution efficiency, a combined arc-length/line-search algorithm is developed and shows an optimum effectiveness and efficiency in large strain elasto-plastic analyses. In addition, a particular treatment of the usage of consistent tangent stiffness is considered.; Finally, the presently developed methods with aforementioned features are applied to sheet metal forming benchmark tests, which include an circular blank with an axisymmetric punch and a more challenging three dimensional square punch. It is shown that the present analyses are in good agreement with the available references. |
