Analytical model for coupled torsional-longitudinal vibrations of marine propeller shafting system considering blade characteristics

As an attempt to investigate the torsional-longitudinal vibrations of marine propeller shaft-ing systems, this paper develops an integrated mathematical formulation to consider dif-ferent aspects of the problem as clearly as possible. The previous works in this field mostly deal with the lumped-parameter or finite element simulations of the propeller and the main shaft while this paper employs a non-FEM distributed-parameter modeling. The Newton-Euler method is used to derive dynamic equations of the cantilever blading and the rotating main shaft. The lumped effects on the main shaft such as the thrust block, the rigid coupling and the propeller loadings are considered together with the variation of cross section and pretwist angle along the blades. Galerkin method is used to discretize the equations and find the lowest number of dominant modes for each degree of freedom. The coupling effect is then explained by classifying the mode shapes into three groups. It is found that taking blade deformations into account is advantageous to the vibration analysis of the problem. (c) 2021 Elsevier Inc. All rights reserved.

Automated summary

This paper investigates the torsional-longitudinal vibrations of marine propeller shafting systems by developing an integrated mathematical formulation, considering lumped effects on the main shaft and blade deformations. The non-FEM distributed-parameter modeling and Galerkin method are employed to analyze the problem, showing that taking blade deformations into account is advantageous for vibration analysis.