Inverse Identification of the Constitutive Equation of Inconel 718 and AISI 1045 from FE Machining Simulations

Until now, the progress, which was achieved in the field of computer technology, could not be used to broadly introduce FEM-modeling techniques in the machining sector of the manufacturing industry. Despite the potentials of modeling cutting processes with the FEM, such as predicting tool loads and chip forms, there are obstacles, which hinder a successful adoption. One of the most challenging aspects is the modeling of the viscoplastic workmaterial behaviour during machining processes. In the past expensive and time-consuming exper- iments like the Split-Hopkinson Pressure Bar Test were used to obtain material data at the extreme conditions of cutting (T close to Tmelt, strains ∼ 5, strain rates > 106). New, inverse methods of identifying the flow stress data are faster, easier to execute and potentially more accurate.This paper applies a new methodology to inversely identify the flow stress data in orthogonal cutting, which was originally developed at the ISM of the University of Kentucky, USA, and the WZL of RWTH Aachen University, Germany. The derived method is applied to identify the flow stress data of Inconel 718 and steel AISI 1045 in order to create 2D FE-models of the orthogonal cutting process for various cutting conditions. The models are validated by experiments on a specially designed test set-up on a broaching machine, which is distinguished by other orthogonal cutting tests by the straight geometry of the workpiece, which allows a direct comparison with 2D FE- simulations. The experiments include highspeed-filming the chip formation, measuring the cutting forces and temperatures.