On the importance of the choice of the parameters of the Johnson-Cook constitutive model and their influence on the results of a Ti6Al4V orthogonal cutting model

Abstract

A wide range of parameters is available in the literature for the Johnson-Cook constitutive model, the most used flow stress in metal cutting modelling. This strength of the Johnson-Cook model is also a weakness as it is therefore difficult to choose the set that will provide the most accurate results. Indeed, for a given material, several parameters are available due to different identification conditions (strain, strain rates and temperature range). This paper gathers the sets of Johnson-Cook parameters from the literature for Ti6Al4V before comparing them based on their stress-strain curves. The twenty identified sets are then introduced in a Coupled Eulerian-Lagrangian (CEL) finite element orthogonal cutting model and their results are compared at fixed cutting conditions. This comparison is then extended for the three most characteristic sets to two other uncut chip thicknesses. All the numerical results are compared to an experimental reference in the same cutting conditions. Links between the parameters of the Johnson-Cook flow stress and outputs of the model are then highlighted; they are still valid when the uncut chip value is modified. A set is finally recommended to obtain an accurate estimation of the cutting force and average feed force and chip thickness values.