Nonlinear chatter of CNTs-reinforced composite boring cutter considering unstable region

The nonlinear dynamic analysis of rotating composite boring round bar containing carbon nanotubes (CNTs) in boring system is investigated. Firstly, according to both the Halpin–Tsai model and the micro-mechanical theory, the resultant properties of filled-CNT composite material are estimated. Subsequently, the equations in terms of the energies and virtual works for the composite boring bar are derived by taking into the Von Kármán geometric nonlinearity account. Then, the extended Hamilton principle is used to establish the nonlinear dynamic model of the machining system, which includes periodic regenerative chatter cutting force, periodic frictional force, viscoelastic and process damping force. Both methods of Galerkin approximation and multiple time scales for nonlinear equation are utilized to obtain steady-state response of the boring process. The stability of the boring system is explored considering the effects of CNT-related parameters, fiber volume fraction and orientations, stacking sequences, damping coefficient, and cutter geometry features. The results obtained demonstrate that the CNTs inclusion has a considerable effect on the dynamic behavior of the boring process. Furthermore, it is also concluded that the unstable area can be reduced by increasing damping and that the stability of boring process will be enhanced.