A comparison of process damping modelling as local flank face interaction and as macroscopic modal feature in a time domain machining simulation

Abstract

Dissipative components of tool-workpiece interaction are of major importance in cutting-related vibrations. At the macroscopic vibration scale, such dissipation is usually accounted for by additional generalized damping forces in the equation of motion of the system’s elastodynamics. A finer consideration at cutting edge scale would bring up a line-distributed force mostly of ploughing nature. These two scales are usually linked by analytical integration, involving simplifying kinematical assumptions. In the present work a comparative investigation is proposed, for a machining operation, considering both representations in a detailed time domain modeling framework. Tool’s cutting edges are represented in a discretized manner, i.e. split into numerous elementary cutters allowing for detailed tool-workpiece interaction force distribution. The matter removal process is modeled via dexel-based surface discretization coupled with finite element-based modal shapes, enabling a consistent machined surface generation representation. Finally, the equations of motion are formulated for modal degrees of freedom and solved by a time marching algorithm. Based on these analyses, the limitations of resulting process damping force terms representations are considered regarding vibrations and interaction force magnitudes.