VERTICAL VIBRATION OF SHIPS COUPLED WITH BOTTOM VIBRATION

The theory has been developed for the calculation of coupled vibration of hull and the bottom in which the bottom is treated as an orthotropic plate and the hull as a Timoshenko Beam. The qualitative characteristics have been clarified in uniform beams, including the effect of transverse bulkhead and the natural frequency of bottom itself. The comparison with model experiment shows the theory can well estimate the frequency and mode of model in air. Also from the comparison the treatment of hydrodynamic inertia in the present theory is found to be essentially adequate and the rough estimation of the correction factor J for the three dimensional flow is 0.4. Using this J-value the calculation for a bulk carrier is in good agreement with the experiment up to 4th mode. The calculation of the response is made on another bulk carrier and the correlation with experiment is found to be reasonable. It is shown that the further study is necessary on the J-factor of hydrodynamic inertia and on the damping to improve the quantitative accuracy of estimation, especially for the higher modes whose frequencies are higher than the bottom frequency. (Author)

• Corporate Authors:

  Mitsubishi Heavy Industries Limited

  5-1 Marunouchi, 2-chome, Chiyoda-Ku
  Tokyo 100,   Japan 
• Authors:
  • Ohtaka, K
• Publication Date: 1973-4

Media Info

• Pagination: 21 p.

Subject/Index Terms

• TRT Terms: Bulkheads (Ships); Coefficients; Hulls; Hydrodynamics; Mass; Numerical analysis; Random vibration; Resonance frequency; Ship structural components; Strain (Mechanics); Vibration
• Uncontrolled Terms: Ship hulls
• Geographic Terms: Japan
• Old TRIS Terms: Added mass; Bulkheads; Hull vibration; Jmhi; Strain energy methods; Transverse bulkheads
• Subject Areas: Design; Hydraulics and Hydrology; Marine Transportation;

Filing Info

• Accession Number: 00050847
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: MTB-83 Tech Bull
• Files: TRIS
• Created Date: Jan 31 1974 12:00AM