Calculation of Free and Forced Lateral Vibrations of a Shaft Line Using Solution Coefficient Vectors

In this paper, the free and forced lateral vibrations of a marine propulsion shafting system on anisotropic supports are computed using the vectors of solution coefficients method. The transverse vibrations are considered in two orthogonal planes. The effect of the oil film in the bearings is taken into account. The stern tube bearing is considered as an elastic support of Winkler’s type. The whirling mode shapes for free vibrations of the system were calculated using the algebraic complements according to I.P. Natanson. The results show a decrease in vertical static deformation due to the distributed weight of the shaft line during the operation of the propelling system. This straightening of the propeller shaft explains the increase in the thickness of the oil film in the stern bearing, as observed by naval engineers.