BENDING MOMENT DISTRIBUTION IN A MARINER CARGO SHIP MODEL IN REGULAR AND IRREGULAR WAVES OF EXTREME STEEPNESS

An experimental investigation was undertaken to deter- mine (1) the lengthwise vertical wave-bending-moment distribution within the midship half-length and (2) the relationship between bending moment and extreme wave steepness, for a MARINER-type cargo ship. A 1/96-scale model was cut to form six segments, which were joined by a flexure beam. The beam was strain-gaged to measure bending moments at the hull cuts at stations 5, 7 1/2, 10, 12 1/2, and 15. The model was tested with normal weight distribution and with an extreme cargo amidship loading in both head and following seas. The range of regular-wave steepness (height/length) was 0.05 to 0.11; the irregular waves had an equivalent full-size significant height of 39 feet. Within practical operational limits of speed for the MAR- INER-type ship, the maximum wave bending moments in high regular waves were found to occur in the region from amidship to 0.125L aft of amidships. Thus the practice of concentrating on midship bending moments both in design studies and full-scale measurements appears to be justified for ships of the MARINER-type. Hogging and sagging moments at any section were found to be generally proportional to wave height, up to a wave-height to wave- length ratio of 0.11, the steepest wave that could be generated. The bending-moment and wave data from the test in irregular waves were processed by spectral analysis to obtain equivalent regular-wave responses. These were shown to be, generally, in good enough agreement with the bending-moment response obtained directly in regular waves to inspire confidence in the use of regular-wave response operators and spectral-analysis technique to predict the vertical wave bending moment of a ship in irregular waves

• Supplemental Notes:
  • Project name is Bending Moment Determination
• Corporate Authors:

  Ship Structure Committee

  National Academy of Science, 2101 Constitution Avenue, NW
  Washington, DC  United States  20418

  Naval Ship Engineering Center

  3700 East-West Highway
  Hyattsville, MD  United States  20782
• Authors:
  • Maniar, N M
  • Numata, E
• Publication Date: 1968-11

Media Info

• Features: Figures; References; Tables;
• Pagination: 33 p.

Subject/Index Terms

• TRT Terms: Bending stress; Flexural strength; Ships; Wave height; Waves
• Identifier Terms: Ship Structure Committee
• Old TRIS Terms: Irregular waves
• Subject Areas: Marine Transportation; Materials; Vehicles and Equipment;

Filing Info

• Accession Number: 00007514
• Record Type: Publication
• Report/Paper Numbers: SSC-190 Final Rpt
• Contract Numbers: Nobs 88263
• Files: TRIS
• Created Date: Dec 22 1974 12:00AM