Influence of Friction Damping on Workpiece-Fixture System Dynamics and Machining Stability

Abstract

In this paper, a dynamic model that considers the vibrations of both the workpiece and fixture elements in order to accurately predict the friction damping over a wide range of clamping forces has been developed. The model is established based on the theory of variational inequality and solved via a nonlinear FEM. It is shown that the model is capable of predicting the system dynamics over a wide range of clamping forces. It is also demonstrated that the increasing then decreasing trend of the damping ratio caused by “interface locking” is due to the relative velocity change at the contact interface. With multiple contact interfaces, the “locking” occurs sequentially. Finally, the model is used to study the influence of friction damping on machining process stability.