Thermomechanical modeling of crystallographic anisotropy effect on machining forces based on crystal plasticity framework

Abstract

In this work, the effect of the crystallographic anisotropy on machining forces is studied through a thermomechanical approach based on rate sensitive plasticity based model. A crystal plasticity framework is adopted to formulate the required constitutive equations. The present approach takes into account the material thermoviscoplastic response, the shear strain rate distribution in the primary shear zone and their effects on the lattice rotation. The machining forces as well as the corresponding specific energies are calculated using two methods: (a) the total power minimization procedure and (b) the Merchant shear angle procedure. The proposed model is validated using cutting force data available in the literature. Then, it is used to gain insight into the effect of the crystallographic anisotropy on machining forces. According to the results, a strong dependence of the machining forces to the crystallographic orientations is obtained. The model is also used to analyze the of the cutting velocity on the shearing along crystallographic slip systems through the material thermomechanical response. In addition, it is observed that, compared to the total power minimization procedure, the Merchant shear angle procedure allows capturing the specific cutting energy trends due to the crystallographic anisotropy, in terms of peaks and valleys.