A coupled in-situ measurement of temperature and kinematic fields in Ti-6Al-4V serrated chip formation at micro-scale

The present paper describes and uses a novel bi-spectral imaging apparatus dedicated to the simultaneaous measurement of kinematic and thermal fields in orthogonal cutting experiment. Based on wavelength splitting, this device is used to image small scale phenomenon (about 500×500μm area) involved in the generation of serrated chips from Ti-6Al-4V titanium alloy. Small to moderate cutting speeds are investigated at 6000 images per second for visible spectrum and 600 images per second for infrared measuresments. It allows to obtain unblurred images. A specific attention is paid to calibration issue including optical distortion correction, thermal calibration and data mapping. A complex post-processing procedure based on DIC and direct solution of the heat diffusion equation is detailed in order to obtain strain, strain-rate, temperature and dissipation fields from raw data in a finite strains framework. Finally a discussion is addressed and closely analyzes the obtained results in order to improve the understanding of the segment generation problem from a kinemtatic standpoint but also for the first time from an energetic standpoint.