ANALYSIS METHODS OF CRANKSHAFT'S STIFFNESS CHARACTERISTICS

Abstract

Development of on-line diagnostic (monitoring) method of marine propulsion system working parameters is the authors' target. Crankshaft springing characteristics are one of the most important from the ships' main engines reliability point of view. Planned monitoring system will be able to verify crankshaft springing characteristics by continuous measurements of the crankshaft free-end's axial deformations. Development of the analysis methods of crankshaft's stiffness characteristics is the first step of planned SHM system. The main purpose of research is method developing of the springing analysis for the marine crankshafts in the high-power engines. Crankshaft modeling method, by Finite Element Method, has been discussed. Short overview of the crankshaft boundary conditions is presented. Bearings' oil film stiffness characteristics, ship hull stiffness characteristics and temperature deformation of the ship hull and main engine body are taking into account. Influence of the crankshaft's foundation stiffness on springing values is analysed. During the analyses it was proved that flexibility of engine foundation has a big influence upon the value of crankshaft springing. The authors' method of cylindrical mass and gas forces decompositions has been presented. Analysis of modeling precision of piston-crank system's forces has been performed. Results of calculations are well compatible in the terms of quality with the measurements data.