A CONTRIBUTION ON THE ROTATIONAL FLEXURAL VIBRATIONS OF SHIP'S SHAFTING

While the torsional vibrations of line shafting can be treated as autonomous vibration phenomena, flexural and longitudinal vibrations are dependent functions of the exciting propeller, the double bottom ship's afterbody and ship's hull. The existence of flexural resonances at nominal rpm has been demonstrated in a number of recent studies. For the analysis of these vibrations the conventional treatment of the shaft as a continuous girder is inadequate and FEM models of the shaft and double bottom become necessary. The paper presents a calculation model in which the shaft, the propeller and the anisotropic bearings are represented as discrete stiffeners and dampers. The shaft is made up of continuous flexural rods according to Euler-Bernoulli theory, while the propeller is considered as a rotating disc of transversely vibrating mass. As edge conditions for the transmission from engine to gearing, freely rotating bearings or fixed end constraints are possible. The individual elements of the model and the analytical programme are presented, i.e. 1. continuous flexible beam; 2. stern tube bearing; 3. intermediate bearing; 4. determination of oil film parameters; 5. gyroscopic action of the propeller; hydrodynamic propeller coefficients; calculation program for rotational flexural vib rations. The application of the method is illustrated by a calculated example.

  • Supplemental Notes:
    • Schiffbauforschung, 22 <1983>, p. 225 <No. 4> (10 pp.)
  • Authors:
    • Thorbeck, H
  • Publication Date: 1983

Language

  • German

Subject/Index Terms

  • Subject Areas: Marine Transportation;

Filing Info

  • Accession Number: 00686039
  • Record Type: Publication
  • Source Agency: British Maritime Technology
  • Files: TRIS
  • Created Date: Aug 14 1995 12:00AM