Dynamic Modeling and Dynamic Response of the Coupled Propulsion Shaft-Shell System in an Underwater Vehicle

The vibration generated by the propulsion system can substantially impact the stable navigation and acoustic stealth performance of the underwater vehicles. The coupling vibration between the propulsion shaft system and shell is pivotal to the characterization of the system’s dynamic response. Prior studies have mainly devoted attention to the propulsion shaft system or the shell vibrations, while the coupled shaft-shell dynamics has received limited attention. It is inadequate for accurately predicting the propulsion system vibration responses. Therefore, a coupled dynamics model of the propulsion shaft system and shell is constructed in the present work, in which the shaft-shell interaction is incorporated simultaneously. An experimental platform for the coupled system is constructed, and the proposed dynamics model’s correctness is assessed through a comparison between measured responses and numerical simulations. The effect of the shaft-shell connection stiffness on the various components’ vibrations in the propulsion system is further analyzed. The time and frequency domain analysis results in the propulsion system show that the shaft vibration level decreases monotonically as the connection stiffness increases. The shell vibration varies nonlinearly with the connection stiffness. Specifically, as the connection stiffness increases, the shell vibration first increases and then decreases. Connection stiffness has different effects on the propulsion system component’s vibration. The appropriate connection stiffness can simultaneously prevent excessive vibration in both the propulsion shaft system and shell. The research findings provide theoretical basis for the design and vibration mitigation of the underwater vehicle propulsion system.