Study On The Curve Axis Model And Load Characteristics Of Bearing Of Marine Propulsion Shafting

As the heart of the ship,the ship propulsion shafting is one of the most important parts of the ship power plant.The working performance of ship propulsion shafting plays an important role in the ship’s stability and acoustic stealth performance.Because of the limitation of the technology of manufacture and installation of shafting alignment,there are still some problems in the propulsion shafting of domestic ship,such as serious bearing wear and larger vibration and noise of shafting.Therefore,it is necessary to study the method of shafting alignment,the bearing capacity of bearing and the vibration characteristics of shafting further.Based on the calculating method of shafting alignment and bearing hole arrangement method for compliance with deflection curve of shafting,the curvilinear axis model which is suitable for shafting alignment and bearing dynamic characteristics analysis is proposed in this paper.Based on the numerical analysis method and ANSYS software,the bearing characteristics and the transverse vibration characteristics of the shafting bearing are also studied.The influence of bearing structure and shafting alignment parameters on the bearing capacity and the dynamic characteristics of the shafting is revealed.The related methods and experience of optimizing the structure of shafting and reducing the vibrations of shafting are also obtained.The main work of this paper is as follows:(1)Based on the theoretical analysis and experimental study,the curve axis model of the propulsion shafting is put forward.The dynamic and static characteristics of the shafting under the curve shaft model are summarized,and then the related technical methods of ship shafting alignment calculation and axis precise measurement and control are analyzed.(2)The model of lubrication characteristics of hydrodynamic journal bearing is established in this paper.Based on the dimensionless Reynolds equation and its boundary conditions,the numerical calculation model of hydrodynamic journal bearing is established considering the structural parameters of the bearing,the misalignment angle between the journal and the abrasion of the bush,and the solution program is developed on the MATLAB platform.The distribution of fluid pressure and liquid film thickness in radial sliding bearing is obtained,and the effects of eccentricity of journal,length-to-diameter ratio of bearing,misalignment angle error and bearing wear on the pressure distribution of bearing liquid film are also described.(3)In this paper,the bearing characteristics of sliding bearing under different factors are analyzed.Based on the study of the liquid film pressure characteristics of the bearing,the numerical model for bearing capacity,bearing stiffness and friction is established in consideration of the inclination and deviation of journal,bearing wear and bearing structure parameters.The influence of various factors on the dynamic and static bearing characteristics of the bearing is analyzed comprehensively,which has important guiding significance for the alignment of the shafting and bearing performance.(4)The finite element model of the shafting modal analysis and harmonic response analysis is established based on the simulation shafting.Based on the finite element ANSYS software,the transverse vibration modal analysis and the response prediction of the shafting are carried out.The effects of the bearing support spacing,bearing stiffness,effective contact length and the cantilever length of the stern shaft on the transverse vibration characteristics of the shafting are investigated,which lays a theoretical foundation for the optimization of shafting structure layout and reducing the vibration of shafting effectively.