Dynamic Modeling and Simulation of a Propulsion Shaft System Considering the Bearing Clearance

The propulsion shaft system (PSSM) has a significant complex working conditions due to the fluctuating propeller thrust and torque. Most previous works investigated the PSSM vibrations ignored the supporting bearing and thrust bearing nonlinearities and clearances. The vibrations of the PSSM obtained by those works are unreasonable, especially the transverse vibrations. This work establishes an improved PSSM dynamic model. The PSSM consists of a shaft, a deep groove ball bearing, a thrust ball bearing, and a propeller. The bearing clearance and nonlinearity effects are included. Moreover, the vibrations of the bearing components and shaft flexibility are considered. The flexible shaft dynamic equitation is established based on the Timoshenko beam theory. The effects of fluctuating propeller thrust and torque on the PSSM longitudinal and torsional vibrations are considered. The effects of the bearing clearance on the PSSM dynamics are investigated.