Experiments and FEM Simulations of Milling Performed to Identify Material Parameters

An inverse method of identification for the determination of material parameters that are used for the FEM simulation of milling processes is proposed. First of all, a special device has been instrumented and calibrated to perform force and torque measures, directly during milling experiments in using a piezoelectric dynamometer and a high frequency charge amplifier. The experimental results were saved and low pass filtered to obtain a data measured basis reliable and accurate. Then FEM simulations of milling were performed using explicit ALE based FEM code. The material behaviour is firstly described from a Johnson-Cook constitutive law and different characterization test have been lead in a wide range of conditions to be use to identify a new behaviour law adapted to the process. A fracture model was also added to consider chip formation and separation. Finally, identification procedures are proposed for the determination of material law parameters. These procedures are based on an objective function to minimize, firstly defined by the experimental and numerical results obtained in the turning process and secondly by the experimental and analytical results obtained in milling process. The identification approach is mainly based on the Surfaces Response Method in the material parameters space, coupled to a sensitivity analysis. A Moving Least Square Approximation method is used to accelerate the identification process. This method of identification is here applied for a 304L stainless steel and the first investigations are presented.