Axial vibrations of the ship power transmission system: propulsion shaftline - engine crankshaft

Abstract

A computerized calculation method of the axial vibrations of a ship power transmission system is presented. The vibrations may cause increasing failure frequency of the engine crankshaft and be a source of dangerous ship hull and suprestructure forced vibrations. The shaftline axial vibrations are coupled with the torsional-bending vibrations through the engine crankshaft and are forced by the propeller induced hydrodynamic forces ( if torsional - axial coupling is taken into account ). Several computer algorithms for analyzing the problem have been elaborated by the author. Nonlinear algorithms for determining the dynamic characteristics of thrust bearing, engine main bearing and axial detuner are also presented. A crankshaft deformation analysis was carried out to determine coupling coefficients of the torsional, bending and axial vibrations. Sample calculations of ship axial vibrations were performed and compared with experimental results.