Finite element modeling (FEM) of machining has recently become the most attractive computational tool to predict and optimize metal cutting processes. High speed computers and advanced finite element code have offered the possibility of simulating complex machining processes such as turning, milling, and drilling. The use of an accurate constitutive law is very important in any metal cutting simulation. It is desirable that a constitutive law could completely characterize the thermo-visco-plastic behavior of the machined materials at high strain rate. However, there exist several constitutive laws that are adopted for machining simulation, the choice of which is difficult to make. The most commonly used law is that of Johnson and Cook (JC) which combines the effect of strains, strain rates and temperatures. Unfortunately, the different coefficients provided in the literature for a given material are not reliable since they affect significantly the predicted results (cutting forces, temperatures, etc.). These discrepancies could be attributed to the different methods used for the determination of the material parameters. In the present work, three different sets of JC are determined based on orthogonal machining tests. These three sets are then used in finite element modelling to simulate the machining behavior of Al 2024-T3 alloy. The aim of this work is to investigate the impact of the three different sets of JC constants on the numerically predicted cutting forces, chip morphology and tool-chip contact length. It is concluded that these predicted parameters are sensitive to the material constants.

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