SENSITIVITY ANALYSIS OF METAL-FORMING PROCESSES INVOLVING FRICTIONAL CONTACT IN STEADY-STATE

A simple element to model frictional contact in steady state metal for ming processes is presented together with the sensitivity analysis to the friction coefficient in a Coulomb friction law. The interest of su ch model arises from the analysis of rolling processes and a two dimen sional approach to cutting problems, where the contact zone is to be d etermined, however a stationary state is present in most part of the o peration. The flow approach proves to be an adequate method to handle efficiently this situation. The contact elements impose a restriction in the velocity component normal to the boundary and a tangential fric tion force opposite to the velocity. The parts of the boundary which a re not in closed contact are treated as free surfaces, which must fulf ill the condition of being streamlines. Sensitivity analysis with resp ect to the friction coefficient is performed by the Direct Differentia tion Method (DDM). The effect of variations in this parameter is discu ssed for the simulation of an extrusion and a cutting problem.