During the design stage for a new ship, the requirements for detailed vibration studies must be balanced against their cost. It is possible to concentrate on the main types of vibration; the propeller is the most common source of superstructure excitation (it is responsible in 80% of cases), and local vibration of decks and panels is the dominant type of vibration. Advanced computerised means are available for studying vibration behaviour at the design stage, but initial design surveys should be carried out before any extensive calculations are done. The Authors, of Det norske Veritas, discuss these problems of propeller-induced hull vibration and its analysis in some detail, and several conclusions are drawn. A step-by-step study should be carried out, starting with simple methods and using engineering judgement, to improve the design at an early stage and to identify items for more detailed studies. Propeller excitation may be analysed by various methods ranging from simple statistical estimates for conventional propellers to methods based on lifting-line and lifting-surface theory for unconventional ones. Cost-optimal analysis models for hull vibration call for settling three main questions: (i) separation of models for global and local vibrations, (ii) two-versus three-dimensional models, and (iii) extent of models. Some conclusions are also drawn on modelling and finite-element techniques, on reducing the number of degrees of freedom in natural-frequency analysis, and on using the conventional added-mass approach rather than liquid elements, all in the interests of avoiding unnecessary expense.

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  • Corporate Authors:

    IPC Industrial Press Limited

    Dorset House, Stamford Street
    London SE1 9LU,   England 

    IPC Industrial Press Limited

    Quadrant House, The Quadrant
    Sutton, Surrey,   England 
  • Authors:
    • Carlsen, C A
    • Skaar, K
    • Kucharski, M
  • Publication Date: 1979-11

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Filing Info

  • Accession Number: 00310893
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Files: TRIS
  • Created Date: May 7 1980 12:00AM