DAMPED HULL VIBRATIONS OF A CARGO VESSEL -- CALCULATIONS AND MEASUREMENTS

The hull vibrations of the 9,940/12,200-dwt, 14,200-bhp cargo liner Koudekerk, as measured full-scale with the aid of a mechanical exciter, had previously been compared with the results of finite-element calculations in which the computer program DASH was used. These calculations did not take damping into account, and various formulations for damping were studied; "stiffness damping: (viscous damping with the damping matrix proportional to the stiffness matrix) gave the best results in the frequency range of interest, and, when applied in a three-dimensional finit-element representation of the ship, gave good agreement between calculations and measurements. This theoretical work considered response at only the one point where the exciter was installed (in the stern of the ship), and the Author, of the N.S.M.B., extends the investigation of the usefulness of the applied theory to other points in the same ship. The results of this extension of the investigation are presented and discussed, together with an explanation of the methods used. It was concluded that, in the lower frequency range, the response calculations are in good agreement with the measured results in respect to both the values of the natural frequencies and the nature of the response curves. For this frequency range, however, the detailed finite-element model as used in the investigation is not required. This model serves for the calculation of ship response in the higher frequency range, and especially for vibration levels in the superstructure; this was not foreseen when the hull measurements were originally arranged, and no conclusions can be made in this respect. For hull-girder vibration level, it was found that the trend and the level of the calculated response were in good agreement with the measurements; to quantify the observed differences, the effect of noise on the results of the vibration measurements must first be investigated; noise can be expected to lead to the response values being too high.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00366099
• Corporate Authors:

  Wyt & Zonen B.V.

  Pieter de Hoochweg 111
  Rotterdam,   Netherlands 
• Authors:
  • Hylarides, S
• Publication Date: 1976-11-12

Media Info

• Features: References;
• Pagination: 8 p.
• Serial:
  • Schip en Werf
  • Volume: 43
  • ISSN: 0036-6099

Subject/Index Terms

• TRT Terms: Damping (Physics); Finite element method; Hulls; Measurement; Vibration
• Old TRIS Terms: Hull vibration; Vibration measurement
• Subject Areas: Environment; Marine Transportation;

Filing Info

• Accession Number: 00156278
• Record Type: Publication
• Source Agency: British Ship Research Association
• Files: TRIS
• Created Date: Jun 22 1977 12:00AM