Finite element analysis of high-velocity multi-blow forging processes using explicit time integration scheme

Abstract

The impact forging process using an energy-restricted type machine such as a hammer has long been a basic metal working method. In order to understand the characteristics of a multi-blow impact forging process and achieve a proper die design and effective manufacturing plan, it is necessary to look into an effect of various process variables intensively. However, due to the difficulty involved in theoretical analysis and experiment, the research works relating to this process have remained rather limited. The main objective of the present study is to develop an efficient three-dimensional elastic-plastic finite element formulation and code using the explicit time integration scheme and to apply the developed finite element code to the numerical analysis of the impact forging process. A three-dimensional explicit finite element formulation has been presented by considering the effects of strain hardening, strain rate hardening and thermal softening. An elastic-plastic finite element program using the explicit time integration method has been developed so as to analyze the dynamic behavior of the impact forging precisely. Furthermore, a robust, stable and very accurate stress integration algorithm has been implemented in the developed explicit program, and the error analysis of this algorithm has been performed. In order to check the validity of the developed explicit program, the copper blow test performed on a 350 kJ counterblow hammer has been simulated. Also, an implicit time integration rigid-plastic finite element formulation considering the inertia effect has been presented. A rigid-plastic finite element program using the implicit time integration has been developed and applied to the copper blow test simulation to compare with the explicit method. As a result of the copper blow test simulation using the explicit program and the implicit program, it has been found that the calculated results have good agreements in the available plastic deformation ener...