抄録
In this study, we proposed a new formabiliry testing method for hydroformed tubular products. This test was simulated and evaluated by the finite element method (FEM). The nonlinear explicit FEM program, LS-DYNA was used in the simulation. This new method is performed by changing the cross section of a circular tube to a tapered box shape. In order to determine the suitable testing conditions and the die geometry and dimensions, process parameters (friction coefficient μ, axial penetration parameter m) and material variables (n-and r-values) were taken as the influencing factors in the simulation. As a result, we found that the nominal die-fitting ratio (NDFR) obtained by measurement of the maximum tube expansion is an easy evaluation parameter. The suitable die angle, at which the die-fitting ability can be characterized, is predicted to be between 10 and 15 degrees. The possibility of combination with a taper die and a kite shape is shown as a hydroforming test for the various complicated hydroformed parts.
