FINITE ELEMENT MODELING AND THREE-DIMENSIONAL SIMULATION OF THE TURNING PROCESS INCORPORATING THE MATERIAL HARDNESS

Newly developed functionally graded workpieces made of AISI 6150 (51CrV4), pose great challenges to the machining process due to the combination of different material properties (e.g., hardness) within one workpiece. A material model including more information than experimentally identified stress-strain curves for different temperatures is necessary to model the process more realistically. Therefore, the Johnson-Cook material model has been implemented for three-dimensional turning simulations within the Finite Element software DEFORM (TM) 3D. This paper outlines the adopted method to modify the parameters of the Johnson-Cook material model for two-dimensional and three-dimensional FE-simulations in order to take material hardness into account. The primary objective was to improve passive and feed force computation by using this modeling approach, as it was observed that common material modeling showed large deviations of the feed force and passive force from the measured force components. The calculated feed force and passive force, as well as the cutting force, are validated experimentally. In conclusion it is shown that the application of the Johnson-Cook material model reveals more valid results for modeling the turning of workpieces with varying hardness values.