UNDERSTANDING OF FINITE ELEMENT ANALYSIS RESULTS UNDER THE FRAMEWORK OF OXLEY'S MACHINING MODEL

ABSTRACT We introduce an accurate coupled thermo-mechanical finite element analysis (FEA) of machining using the Arbitrary Lagrangian Eulerian (ALE) analysis capability of ABAQUS/Explicit. This analysis provides detailed information about the cutting forces, chip thickness, contact length, the extent of the primary and secondary shear zones as well as the distribution of strain, strain rate and temperature in the deformation zones. This information has to be viewed under the framework of an analytical model for it to lead to better understanding of the physics of machining. We use the best available analytical model, namely, Oxley's machining model, for this purpose and the FEA results are compared with the assumptions and predictions of Oxley's analysis. The strain rate in the primary shear zone, the hydrostatic pressure variation along the shear plane, the distribution of normal and shear stresses along the tool-chip interface and the shape of the secondary shear zone are the quantities compared. Due to the key role of temperature in the prediction of tool wear, the fraction of heat conducted away into the workpiece, the maximum temperature along the tool-chip interface and the maximum temperature along the flank face are also compared. The comparison reveals that Oxley's model captures the physics of machining quite well. However, some details such as the heat partition module and the assumptions on stress and temperature distribution at the tool-chip interface need to be revisited.