In-situ characterization of thermo-mechanical deformation fields based on DIC during orthogonal cutting of Ti6Al4V

Abstract

Cutting phenomena containing abundant kinematic and thermo-mechanical information during the cutting process provide direct evidence for investigating machining mechanisms. In-situ digital image correlation (DIC) measurements are important methods for obtaining dynamic data such as strain and strain rate during the material deformation process. However, the secondary development of those deformation data is limited. The deformation information obtained by DIC is also limited to understanding complex thermo-mechanical deformation. In this study, an in-situ imaging system was developed to simultaneously acquire gray and infrared radiation (IR) images within the same deformation area during orthogonal cutting of Ti6Al4V. The deformation evolution and thermal history can be obtained simultaneously. In addition, a postprocessing methodology based on the DIC was proposed to derive thermo-mechanical information. Based on the postprocessing methodology, the stress fields were determined by the constitutive equation combined with the strain, strain rate, and temperature data. The stress propagation path during the formation of the chip segment was determined. Finally, the strain energy fields were derived to assess the potential energy of plastic deformation with the generation of the adiabatic shear band. The dependency between the machining phenomena and the cutting parameters was investigated. This work provides a novel understanding of the thermo-mechanical coupling behavior during the generation progress of serrated chips. The nature of the formation mechanisms and the deformation process involved for serrated chips are closely revealed.