Analysis And Experimental Study On Longitudinal And Transverse Coupling Vibration Characteristics Of Ship Propulsion Shafting

The ship propulsion shafting is an important part of the ship power system.With the gradual development of the ship towards large-scale,the ship propulsion shafting also gradually presents the characteristics of long span and multi support.In addition,its excitation is complex,so the coupling vibration of the ship propulsion shafting often occurs,accompanied by large noise and complex frequency components.In order to explore the mechanism and characteristics of vertical and horizontal coupling vibration of ship propulsion shafting and provide theoretical and technical basis for the reduction of vertical and horizontal coupling vibration of ship propulsion shafting,ship propulsion shafting is taken as the research object,and the influence analysis of its vertical and horizontal coupling vibration characteristics as well as the experimental analysis are carried out based on the reasonable alignment.The main research contents of this paper are as follows:(1)Based on the analysis of the composition of ship engine and alignment method and support characteristics of ship propulsion shafting,the mechanism of vertical and horizontal coupling vibration is analyzed.Based on the equivalent design theory,the similarity criterion is derived.The vertical and horizontal coupling vibration equation of beam unit is derived and the numerical model of support characteristics of hydrostatic sliding bearing is established.The Reynolds equation is discretized by finite difference method and the solution of oil cavity pressure is put forward.(2)The element matrix of the vertical and horizontal coupling vibration in beam element of the ship propulsion shafting is deduced by the finite element method,and the vertical and horizontal coupling vibration dynamic model of the ship propulsion shafting is established.At the same time,the finite element model is also established in ANSYS software for comparison.Based on the reasonable alignment,the bearing load of the shafting is solved by the transfer matrix method,and the oil film pressure distribution of the hydrostatic bearing is solved by the over relaxation iterative method.The oil film stiffness and support stiffness are further solved.(3)Based on the vertical and horizontal coupling dynamic model of ship propulsion shafting,Matlab software is used to solve its inherent characteristics,and Newmark-β method is used to solve the dynamic response of the vertical and horizontal coupling vibration dynamic characteristic.The effects of coupling effect,bearing position,support stiffness,oil pressure and alignment state among the reasonable alignment on the natural characteristics and dynamic response are analyzed.(4)The scale reduction test-bed of ship propulsion shafting is designed and built,and the experiments on the natural characteristics and dynamic response of vertical and horizontal coupling vibration of propulsion shafting based on virtual instrument technology is carried out.Vertical and horizontal coupling vibration performance under the different alignment states among the reasonable alignment and pressures situation is carried out.The correctness of the theoretical analysis based on the analysis results are verified,and based on the experiment data,the vertical and horizontal coupling vibration reduction strategy is put forward concerning about the experiment result.