A Simplified Approach of the Coupled Vibrations of the Two-Stroke Marine Engine Shaftings

Due to the complicated shape of the marine diesel engine crankshaft, its deformations also have a complex nature causing coupling phenomena among its individual vibration types: torsional, bending and axial. Up to now, the vibrations of shafting systems driven by marine diesel engines were in general calculated by considering only the torsion and axial coupling, or by much simplifying the real formula of the crank. The present study proposes a more flexible and realistic model (based on the finite element method (FEM) for the calculation of the excitations on coupled vibrations of marine diesel engines. The model assumes a spatial beam structure with a uniformly distributed mass and concentrated masses in specific nodes. The entire set of exciting forces (including engine and propeller excitations) has been taken into account. This model has been verified through experimental investigations. It has been concluded that the torsion vibrations are dominant relative to the propeller thrust fluctuations in exciting axial vibrations. The method reveals that the axial vibrations reach annoying levels and occasionally indicates the necessity of axial dampers mounting.


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  • Accession Number: 01359009
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 30 2011 6:58PM