Marine Diesel Engine High Strength Bolt Stress Analysis And Fatigue Life Prediction

As we all know,low-speed diesel engines are the main power plants,it is closely related to the safety,reliability,maneuverability and economy of the ship's operation;high-strength bolts are important mechanical connectors,its strength and longevity at work are also the key to the stable operation of low-speed diesel engines.Therefore,in this paper,the performance of low-speed main bearing bolts is studied.The main contents are as follows:Through the material composition analysis and the mechanical properties test of the bolt material,the yield strength,tensile limit and fatigue life of bolt materials under normal temperature conditions were obtained.The fatigue life curves under different average stresses were drawn,and the fatigue fractures are analyzed to obtain the influence of the microstructure of the materials on the life.The relationship between the bolt axial force and the deformation and tested the hardness of the bolt are obtained.In order to predict the marine low speed main bearing bolt stress distribution and fatigue life,a relatively objective test data is provided.Using the contact nonlinear analysis method of ANSYS finite element analysis software,the two-dimensional axisymmetric model of bolt structure is analyzed and calculated.The stress distribution under different preloads is obtained.To find the effect of the working load on the stress distribution of the bolt,the relationship between the preload force and the load fluctuation of the bolt under the same working load is analyzed.The fatigue life curve and finite element analysis results under different average stresses into the fatigue finite element analysis software are introduced,and bolt fatigue life prediction was performed.In addition,the influence of preload and bolt surface roughness on bolt life is also analyzed.