International Journal of CAD/CAM

Society for Computational Design and Engineering (한국CDE학회)
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Parametric Modeling and Shape Optimization of Offshore Structures

  • Birk, Lothar (School of Naval Architecture and Marine Engineering, University of New Orleans)
  • Published : 2006.12.31
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Abstract

The paper presents an optimization system which integrates a parametric design tool, 3D diffraction-radiation analysis and hydrodynamic performance assessment based on short and long term wave statistics. Controlled by formal optimization strategies the system is able to design offshore structure hulls with superior seakeeping qualities. The parametric modeling tool enables the designer to specify the geometric characteristics of the design from displacement over principal dimensions down to local shape properties. The computer generates the hull form and passes it on to the hydrodynamic analysis, which computes response amplitude operators (RAOs) for forces and motions. Combining the RAOs with short and long-term wave statistics provides a realistic assessment of the quality of the design. The optimization algorithm changes selected shape parameters in order to minimize forces and motions, thus increasing availability and safety of the system. Constraints ensure that only feasible designs with sufficient stability in operation and survival condition are generated. As an example the optimization study of a semisubmersible is discussed. It illustrates how offshore structures can be optimized for a specific target area of operation.

Keywords

References

  1. Birk, L. (1998), Hydrodynamic shape optimization of offshore structures. PhD thesis, Technical University Berlin (D83), Germany
  2. Birk, L. (2003), Introduction to nonlinear programming. In Birk, L. and Harries, S. (editors), Optimistic - Optimization in marine design. Mensch & Buch Verlag, Berlin
  3. Birk, L. and Clauss, G.F. (1999), Efficient development of innovative offshore structures. In Proc. of 31st Offshore Technology Conference (OTC' 99), Houston, TX
  4. Birk, L. and Harries, S. (2000), Automated optimization – A complementing technique for the hydrodynamic design of ships and offshore structures. In 1st Int. Conf. on Computer Applications and Information Technology in the Maritime Industries (COMPIT), Potsdam, Germany
  5. Birk, L.; Clauss, G.F. and Lee, J.Y. (2004), Practical application of global optimization to the design of offshore structures. In Proc. of 23rd Int. Conf. on Offshore Mechanics and Arctic Engineering (OMAE' 04), Vancouver, Canada
  6. Chou, F. (1977), A minimization scheme for the motions and forces of an ocean platform in random seas, In SNAME Transactions, 85:32-50
  7. Clauss, G.F. and Birk, L. (1993), Minimizing forces and motions of large offshore structures. In Proc. of 12th Int. Conf. on Offshore Mechanics and Arctic Engineering (OMAE' 93), Glasgow, UK
  8. Clauss, G.F. and Birk, L. (1996), Hydrodynamic shape optimization of large offshore structures. Applied Ocean Research, 18(4):157-171 https://doi.org/10.1016/S0141-1187(96)00028-4
  9. Clauss, G.F., Lehmann, E. and Ostergaard, C. (1992), Offshore Strcutures – Vol. 1 Conceptual design and hydromechanics. Springer Verlag
  10. Evans, J.H. (1959), Basic design concepts. Journal of the American Society of Naval Engineers, 71(4)-671:678 https://doi.org/10.1111/j.1559-3584.1959.tb01836.x
  11. Gregory J.(1986), N-sided surface patches. In Gregory, J. (editor), The mathematics of surfaces. Oxford University Press, New York, 217-232
  12. Hogben, N. and Lumb, F.E. (1967), Ocean wave statistics. Her Majesty's Stationary Office, London
  13. Huang L. (2000), Anwendung von Freiformflächen beim parameter-gesteuerten Entwurf von Offshore Plattformen. PhD thesis, Technical University Berlin (D83), Germany. In German
  14. Jones, E.; Oliphant, T, Pearson, P. and others (July 2006), SciPy: Open source scientific tools for Python. http://www.scipy.org
  15. Lee, C.H. (1995), WAMIT theory manual. Techn. Report, Massachusetts Institute of Technology, Cambridge, MA
  16. Nelder, J. and Mead, R. (1965), A simplex method for function minimization. Computer Journal, 7(308)
  17. Nowacki, H. and Reed, A. (1974), Interactive creation of fair ship lines. Journal of Ship Research, 18(2):96-112, 1974
  18. Rawson, K.J. and Tupper, E.C.(2001), Basic ship theory. Butterworth-Heinemann
  19. St. Denis, M. and Pierson, W. (1953), On the motions of ships in confused seas. In SNAME Transactions, Vol. 61
  20. van Rossum, G. and Drake Jr., F.L. (editors) (2003), The Python Language Reference Manual. Network Theory Ltd