Simulation Research Of Longitudinal Vibration Features Of Large Ship Propulsion Shafting

When the longitudinal vibration of the ship shafting is too large,it may cause fatigue damage to the crankshaft shafting,wear of the acceleration transmission gear,or cause local vibration of the engine room and vertical vibration of the hull girder.For ships,it will also reduce the ship’s acoustic characteristics,causing an unfavorable situation.Therefore,in the ship design stage,it is best to avoid harmful longitudinal vibration resonance speed within the scope of use of the main engine.But in fact,because of the restraint of the dimension of the mechanical construction,the arrange of the shafting and the sort of ships,the occurrence of longitudinal vibration resonance cannot be avoided within the scope of use of the main engine.Therefore,a reasonable speed forbidden zone should be set within the working speed range of the ship,and the speed forbidden zone should also be quicken to refrain the adverse influences of longitudinal vibration resonance.thence,it is considerable to research the effect element of the natural property and response property of shafting longitudinal vibration.in view of the finite element method,main body of a book consider the influencing element on the natural property and response property of longitudinal vibration:First of all,for a certain real ship shafting model,Resume axis equivalent model,and Theoretical calculation of longitudinal vibration of shaftingSecondly,in the light of the each construction parameters of the shafting system,Complete the 3D modeling of the shaft system,and the movement condition of the shafting longitudinal vibration is imitated based on the finite element software,and the bearings in the shaft section are equivalently simulated to complete the shafting longitudinal vibration planning.The contradistinction between theoretical count and finite element count proves the accurateness of the finite element simulation model.Finally,with the shafting model as the examination object,the natural property and response property of the shafting longitudinal vibration are discussed and studied by the method of finite element simulation;the examination indicates that the first two stages longitudinal vibration natural frequencies are related to the water quality of the propeller attached The relationship of linear change,the greater the attached water mass,the greater the natural property of longitudinal vibration,and the smaller the value of the longitudinal vibration resonance;the greater the axial stiffness of the thrust bearing,the greater the natural frequency of the first two longitudinal vibrations,and the value of the longitudinal vibration resonance.The smaller.It has certain guiding significance for the selection of the propeller and the design of the thrust bearing in the ship design stage.