Numerical simulation in bulk forming process

Abstract

Investigation of stress-strain state of bulk forming in open dies has been presented in the paper. By numerical simulations it is possible, by discretization of the process per deformation phases, to determine deformation parameters in all phases. Logarithmic strain tensor components are determined by meridial point cross-section per deformation phase displacements, where a total strain is calculated as a sum of strains obtained in deformation phases. Stress tensor component is determined by the method of higher theory of plasticity. For numerical simulation, DEFORM-2D software package is used, meant to analyze plane and axi-symmetrical deformations. A stepped concave die shape is adopted, as well as working-piece dimensions and node point distribution, whose displacements are fallowed during deformation process. Numerical simulation consists of three phases. In the first phase numerical experiment is carried out, where, for adopted point coordinates in non-deformed state, point displacements at the end of deformation process, are obtained. Stressstrain state parameters are determined on the base of these data at displacement points. The second phase relates to numerical experiment that is carried out for the same initial conditions, but bulk deformation process is observed in deformation phases. In each phase, stress-strain parameters are determined, based on which parameters at the end of deformation process are obtained. The third phase concerns stress state parameters, determined by DEFORM-2D, and they are related to the same initial conditions.