Finite element simulation of saw-tooth chip in high-speed machining based on multiresolution continuum theory

Because the deformation is very large and highly localized in the adiabatic shear bands (ASB) of the saw-tooth chip in high-speed machining (HSM), the physical results of the width and spacing of ASB in saw-tooth chip cannot be given by the traditional finite element method (FEM) due to the mesh dependency. Therefore, a 3D finite element model of HSM based on multiresolution continuum theory (MCT) with a simple algorithm of hourglass control was brought out to predict the saw-tooth chip. The comparison between the simulation results and experimental ones of chip deformation and cutting forces shows the validity of the established model. The formation of saw-tooth chip is analyzed, and the changes of chip morphology with cutting parameters were given. The results show that the MCT model has the ability to capture the width and spacing of shear band of saw-tooth chip in HSM by using a length scale to build the relationship between the macro materials behavior and the microstructure. It can also clearly show the formation of saw-tooth chip. An interesting thing is that during the forming of two adjacent shear bands, there is a transition shear band. The stress of MCT model is slightly larger than that of traditional FEM, but the strain is little smaller and the temperature is little lower. For the cutting force, the simulation results of MCT model are more consistent with experimental ones than that of traditional FEM. The simulation results of chip morphology under the condition of different cutting parameter are consistent with that of experiment.