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A simple problem of tube expansion to fill the die corners in the hydroforming process is studied. Based on a two-dimensional plane stress model the tube is simulated numerically using a static implicit finite element analysis, particularly, the commercial finite element code ABAQUS. Similar to the development and application of two-dimensional finite element codes for sheet metal forming, this two-dimensional model provides insight of the detailed deformation and stress/strain development otherwise lost in a more complex three-dimensional model. To facilitate discussions, high friction is assumed such that the tube does not slide on the die surface after contact. The calculated results predict the requirement to form sharp corners and demonstrate the development of the deformation, strain and stress states in the tube.

WRAPFORM is a mathematical model and computer program for calculating binder wrap surface shape. It employs punch-opening line of the die as a geometric input and does not use the complete binder surface. This paper presents WRAPFORM-II, an improvement of the WRAPFORM model by including the binder surface geometry in the simulation. The new model has been applied to several dies and results are compared to those of the base WRAPFORM model. For a decklid die reported in the literature, whose simulated binder wrap showed bifurcation possibilities, straightforward application of WRAPFORM-II predicts a more plausible result which is consistent with the original design intent. In another case, WRAPFORM-II predicted the feasibility of a design to put more material into the die cavity. Other applications show slightly improved simulation results by using WRAPFORM-II.