Simulation Analysis Of Vibration Characteristics Of One Ship Propulsion System Based On Finite Element And Multi-Body Dynamics Method

Ship propulsion system is one of the important of ship power plant systems, itsreliability is directly related to the safety of the ship. In recent years, the large-scale efficientdevelopment direction, ship propulsion system reliability is put forward higher requirements.So study on propulsion system of ship vibration characteristics has important significance toimprove reliability and control the vibration. In this paper, with one25000tons of chemicalpropulsion system as the research object, its natural vibration and vibration response underexternal loads is respectively investigated. Include the following contents.First of all, the marine propulsion shafting system of three-dimensional finite elementmodel is established, the calculation is performed to the propulsion system of the naturalvibration characteristics, its natural frequency and natural shapes are gained. The mainpropulsion system mode shape deformation of propeller and stern shaft, the propulsionsystem responses in52.2rpm.Secondly, A nonlinear multi-body dynamics model of the ship propulsion system isestablished, the calculation is performed when combustion pressure and propeller excitingforce is loaded on corresponding bodies. Three-dimensional vibration of marine Enginecrankshaft is investigated at rated speed. The vibration response of crankshaft, shaft andpropeller are analyzed, the relative maximum torsional vibration displacement of crankshaftis0.013rad, the longitudinal vibration is a typical type of piston vibration characteristics, thefree end of the longitudinal vibration displacement values is8.35mm. Compared withtorsional vibration and longitudinal vibration, the bending vibration is relatively weak, themaximum bending vibration displacement values is0.68mm. When four cylinder combusts，three-dimensional coupled vibration is occurred strongly. The largest shaft bending vibrationdeformation appeared in the propeller and stern post is positioned between the bearings, thehorizontal bending deformation is0.524mm, the maximum vertical deformation is1.56mm.The response displacement of aft sterntube bearing position is bigger than the other twobearings. The maximum horizontal response displacement of propeller is1.58mm,maximum vertical response displacement is5.66mm, the maximum axial responsedisplacement is15.13mm.