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This paper presents a systematic procedure for the development of a constitutive model of friction with focus on the application in bulk metal forming simulations. The empirically based friction model describes friction as a function of sliding distance and the most relevant friction influencing parameters. The latter were determined by means of designed experiments. An optimal friction model is obtained as a trade-off between model accuracy and complexity by using stepwise nonlinear regression and a modified version of the Akaike information criterion. Within this study, the procedure is applied to determine a friction model for tube drawing. However, the same approach can also be used for modeling friction of any other bulk metal forming process.

This paper presents a fully coupled three-dimensional finite element model for the simulation of a tube manufacturing process consisting of roll forming and high-frequency induction welding. The multiphysics model is based on the dual mesh method. Thus, the electromagnetic field, the temperature field, the elasto-plastic deformation of the weld bead, and the phase transformations within the material can be simulated for a moving tube without remeshing. A comparison with measurements shows that the geometry of the welded tube and the weld bead, the force on the squeeze rolls, the temperature along the band edges, and the hardness distribution within the heat-affected zone can be simulated realistically.