Rigid–viscoplastic dynamic explicit FEA of the ring rolling process

Abstract A generalized energy functional describing rigid–viscoplastic dynamic deformation is newly proposed. The Lagrangian multiplier method and the penalty method are introduced to enforce the incompressibility condition into the functional, respectively. The rigid–viscoplastic dynamic explicit finite element equation is established by employing the functional, in which the penalty method is used to remove the restraint of incompressibility. Then the rate-type explicit time integration formulation is given by the central difference method. A rigid–viscoplastic dynamic explicit finite element code, H-RING, is developed for the analysis of ring rolling. The discussion is mainly focused on an investigation of the cause and elimination of fishtail defect in rectangular section ring rolling and the strain distribution in L-section profiled ring rolling. The constraint of guide rollers is also introduced into the calculation. The numerical analysis results are in good agreement with experiments in terms of geometrical changes and in load variation.