Research On The Impact Of Vibration Isolation For Marine Power Plant To Shafting Vibration Under Ship Rolling

Marine shafting is a system to realize energy transfer between main engine and propulsion facilities. It also transmits axial thrust propeller brought by propeller rotating to hull, becoming a system that drives ship to move forward. In this way it's a vital component among marine power. Shafting usually vibrates under varieties of incentives during ship system operating. Any type of shafting vibration may cause impact on the normal operation of ship, navigating safety and living comforts.After marine power plant is mounted with vibration isolation system, its supporting stiffnesses decrease, which can be seen as elastic supporting status. Under propeller incentives and ship rolling, there will be additional incentives at coupling due to the loss of movement synchronization between power plant and shaft. It may significantly affect the shafting vibration characteristics, bearing loads and elastic coupling displacement supplement,furthermore the safety of shafting and the matching of shafting and power plant. Therefore it's particularly necessary to study the shafting dynamic characteristics under power plant mounting with vibration isolation system.In this paper, the marine propulsion shafting test bench is taken as the investigation target. Vibration isolation system is designed for marine power plant. The impact of power plant vibration isolation system to propulsion shafting vibration under ship rolling is mainly investigated. The primary work is listed as follows:(1) The predigestion of propeller incentives and rolling boundary conditions is illustrated based on the characteristics of propeller invectives and the process of ship rolling.(2) The finite element model of propulsion shafting and power plant is established based on propulsion shafting test bench. Vibration isolation system is designed for the power plant.Validity of the FEM model is discussed through the tests.(3) The impact of power plant vibration isolation system to shafting vibration is studied based on the verified model. Natural characteristics are firstly investigated. Then forced vibration responses are computed under propeller incentives and ship rolling. Shafting vibration characteristics are demonstrated via the comparison of shaft displacements, bearing loads, etc.(4) The matching of shafting and power plant is finally discussed by modifying the stiffnesses of power plant vibration isolation and elastic coupling. Matching principles of power plant vibration isolation system and propulsion shafting are achieved in the end.This paper investigated the impact and matching principles of marine power plant vibration isolation system and propulsion shafting, providing theory foundation for propulsion shafting safely running and its design targeting low noise.