Nonlinear Dynamic Analysis of High-Speed Motorized Spindle Bearing-Rotor System Coupled by Nonlinear Bearing Contact Force and Dynamic Cutting Force

Abstract This paper addresses the complex vibration issues arising from the coupling of nonlinear dynamic cutting forces with internal nonlinear factors in the bearing-rotor system during machining of high-speed motorized spindles. By introducing a dynamic cutting force model and integrating it with Timoshenko beam theory and Hertz contact theory, a coupled dynamic model of the bearings-rotor-cutting system for high-speed motorized spindles is established. Based on this model, the Newmark-β method is employed to solve the dynamic equations and conduct numerical simulations, systematically analyzing the effects of spindle speed and bearing radial clearance on the system's dynamic response. The results reveal that the introduction of dynamic cutting forces significantly alters the system's bifurcation behavior. Through an internal resonance mechanism, it advances the critical instability point and induces period-doubling bifurcation and chaotic motion. Increasing the bearing radial clearance intensifies nonlinear coupling effects, causing the vibration response to evolve from periodic motion through period-doubling and chaos before stabilizing under certain conditions. This reveals the influence patterns of coupled internal and external nonlinear sources on the system's vibration response. This research provides a theoretical basis for structural optimization and cutting parameter selection in high-speed motorized spindles.