A Rate-Sensitive Plasticity-Based Model for Machining of fcc Single-Crystals—Part II: Model Calibration and Validation

Abstract

For a range of precision machining and micromachining operations, the crystallographic anisotropy plays a critical role in determining the machining forces. Part II of this work presents the calibration and validation of the rate-sensitive plasticity-based machining (RSPM) model developed in Part I. The five material parameters, including four hardening parameters and the exponent of rate sensitivity, for both single-crystal aluminum and single-crystal copper are calibrated from the single-crystal plunge-turning data using a Kriging-based minimization approach. Subsequently, the RSPM model is validated by comparing the specific energies obtained from the model to those from a single-crystal cutting test. The RSPM model is seen to capture the experimentally observed variation of specific energies with crystallographic anisotropy (orientation), including the mean value, symmetry, specific trend, amplitude, and phase of the peak specific energy. The effects of lattice rotation, hardening, and material-parameter variations on the predicted specific energies is then analyzed, revealing the importance of both lattice rotation and hardening in accurately capturing the specific energies when cutting single-crystals. Using the RSPM model, the effects of crystallographic orientation, rake angle and friction angle on specific energies are also analyzed. Lastly, a simplified model that uses Merchant’s shear angle, thereby circumventing the minimization procedure, is constructed and evaluated.