A Study Of Rigid-Plastic Finite Element Method Simulation Of Chain Roller's Backward Extrusion Process

In this paper, rigid-plastic finite element method (FEM) was used to simulate the critical forming process of chain roller-backward extrusion process, and joint-element was introduced into the simulation of contact friction area in plastic forming.The matrix equations of rigid-plastic finite element method in noumenon zone were deduced from the basic theory of FEM, combined with the basic theory of rigid-plastic flow rule. The matrix equation of joint-element zone and noumenon-element zone were assembled into a unitary coupling matrix equation through coupling method.According to the coupling matrix equation, we developed an effective program system for simulating the backward extrusion process which gived visible drawing of simulation results.Some special problems in numerical simulation, such as the aquation of Vise-friction factor , the choice of initial velocity field, the convergence criterion of iteration, the treatment of singular point, remesh techique, etc., were analyzed in this paper.Because the initial mesh distorted heavily in the backward extrusion forming process, Marc software was used in this paper to realize the remesh process which made the simulation results more accurate.Then, the forming process of backward extrusion was studied by experiment, and the result of experiment was compared with the datum of the numerical simulation. It is proved that the theory and the program system for rigid-plastic FEM numerical simulation in backward extrusion process is reliable and utility.