Understanding kinematics of the orthogonal cutting using digital image correlation – measurement and analysis

Due to the development of advanced image correlation and high speed filming techniques, the kinematic field during the cutting process can be experimentally determined including the displacement, strain, and strain rate fields. As known, the setting parameters for the digital image correlation (DIC) as well as the optical parameters of the given camera and lighting system have a great influence on the spatial resolution and accuracy of the DIC results. In this study, the speckle pattern in terms of speckle size and intensity distribution are analyzed when using two different surface preparation methods. Moreover, the influences of the subset sizes for the image correlation on the strain and strain rate are numerically studied. Interlaboratory measurements of the kinematic field during the orthogonal cutting of AISI 4140 were conducted with two different in-situ imaging setups. The material flow near the cutting tool edge determined from the velocity field were compared with the numerical simulation. The experiments showed that no stagnation zone exists, however a considerable large stagnation zone was found from the numerical simulation. Furthermore, slip-line fields were constructed from the experimentally determined strain rate components, from which the boundary conditions along the chip free and chip-tool interface were derived.