The statistical values of wave induced stress on the hull girder are generally used for evaluation of the longitudinal strength of the hull, and recently, the square root method is often used as an approximate method. However, to know the actual predicted values, they should be calculated using the combined stresses due to vertical and lateral loads considering the phase lag of those in the regular waves instead of getting the statistical values of each load. Then, a computer program was developed by Nagasaki Shipyard, MHI to evaluate the longitudinal strength of hull girder directly according to the latter method. Using this system, the stress analysis of hull girder on the 210,000 DWT oil tanker was carried out. In this paper, the outline of this computer program and the consideration for above calculations are described. The main conclusions derived in this paper are as follows. (1) The comparison of the statistical stress values from above two methods are carried out and it is found that the values from the approximate method agree pretty well with those derived from a direct method, i.e. the approximate method seems very useful for the designer. (2) The statistical normal stresses at bilge and gunnel are almost the same level and larger than those of deck and bottom center-line by 30 per cent at maximum under full load condition. (3) In general, the normal stresses in full load conditions are larger than those in ballast load condition. This is because of the fact that the lateral bending moment in the full load condition is pretty larger than those in ballast condition according to the difference of draft. (4) The maximum normal stress occurs at the qunnel of leeward side and the bilge of weather side in the quartering sea and at the wave length of the square root of L over lambda equals 1.3-1.4. (5) The ship velocity contributes little to reduction of the maximum stress.

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  • Corporate Authors:

    Mitsubishi Heavy Industries Limited

    5-1 Marunouchi, 2-chome, Chiyoda-Ku
    Tokyo 100,   Japan 
  • Authors:
    • Nagamoto, R
    • Aikawa, N
    • Tsukamoto, O
    • Matsuyama, M
  • Publication Date: 1976-10

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Filing Info

  • Accession Number: 00158257
  • Record Type: Publication
  • Source Agency: Mitsubishi Heavy Industries Technical Review
  • Files: TRIS
  • Created Date: Aug 31 1977 12:00AM