Fig. 1 Cross-sectional view of the left half of a box-shaped model.
Fig. 2 (a) Deck widths of the model and (b) vertical bending stiffness EI at each square station.
Fig. 4 Pictures (a, b) and schematic cross-sectional view (c) of the hydro-structural container ship model. (a) side view, (b) inside the hull. The location of the attached strain gauges are indicated in (c).
Fig. 5 Results of the three-point bending test and torsion test. (a) Correlation between vertical bending strains ∊v and vertical bending moments, (b) correlation between deflection δz and vertical bending moment, and (c) correlation between torsional strain ∊T and torsional moment. BT: beam theory, FE: FE analysis.
Fig. 6 FE analysis for a vertical bending test of a urethane plate with an FBG strain gauge. (a) Schematics of the cantilevered plate, and (b) FE analysis. Location of the FBG gauge is indicated by a red ellipse. The colors indicate the magnitude of normal stress; red: large, blue: small.
Fig. 7 Time series obtained from the decay tests. (a) Vertical bending moment and (b) torsional moment.
Fig. 8 Vertical bending and torsional moments measured in the towing experiment in the regular wave. (a) Time series of the vertical bending moment, (b) frequency spectrum of the vertical bending moment, (c) time series of the torsional moment, and (d) frequency spectrum of the torsional moment.
Fig. 9 Wave elevation, ship motions, and vertical acceleration at FP measured in the towing experiment in the freak wave.
Fig. 10 Vertical bending and torsional moments measured in the towing experiment in the freak wave. (a) Time series of the vertical bending moment, (b) frequency spectrum of the vertical bending moment, (c) time series of the torsional moment, and (d) frequency spectrum of the torsional moment. The lowest natural frequencies are indicated by arrows.
Fig. 3 Vibration-mode analysis with FE models. (a) 1st torsional mode, (b) 1st vertical bending mode.
Table 1 Principal dimensions and quantities related to the midship section. α is the model scale.
Table 2 Designed values related to stiffness at the midship section.
Table 3 Comparison of the wet natural frequencies. Unit: Hz
References
- Bigot, F., Derbanne, Q., Sireta, F. X., Malenica, S., & Tuitman, J. T., "Global Hydroelastic Ship Response Comparison of numerical model and WILS model tests," In The Twenty-first International Offshore and Polar Engineering Conference. International Society of Offshore and Polar Engineers, pp.477-485, 2011.
- Fujimoto, W., Waseda, T., & Webb, A. "Impact of the four-wave quasi-resonance on freak wave shapes in the ocean," Ocean Dynamics, Vol.69 (1), pp.101-121, 2019. https://doi.org/10.1007/s10236-018-1234-9
- Fukasawa, T., Yamamoto, Y., Fujino, M., & Motora, S., "Motion and longitudinal strength of a ship in head sea and the effects of non-linearities (4th report)," Journal of the Society of Naval Architects of Japan, Vol.150, pp.308-314, 1981.
- Hong, S. Y., & Kim, B. W., "Experimental investigations of higher-order springing and whipping-WILS project," International Journal of Naval Architecture and Ocean Engineering, Vol.6 (4), pp.1160-1181, 2014. https://doi.org/10.2478/IJNAOE-2013-0237
- Hong, S.Y., Kim, B.W., Nam, B.W., "Experimental study on torsion springing and whipping of large container ship," International Journal of Offshore and Polar Engineering, Vol.22 (2), pp. 97-107, 2012.
- Houtani, H., Waseda, T., Fujimoto, W., Kiyomatsu, K., & Tanizawa, K., "Generation of a spatially periodic directional wave field in a rectangular wave basin based on higher-order spectral simulation," Ocean Engineering, Vol.169, pp.428-441, 2018. https://doi.org/10.1016/j.oceaneng.2018.09.024
- Iijima, K., Hermundstad, O. A., Zhu, S., & Moan, T., "Symmetric and antisymmetric vibrations of a hydroelastically scaled model," Proc. Hydroelasticity in Marine Technology, University of Southampton, UK., pp.173-182, 2009.
- ITTC: 7.5-02 07-02.6 Rev.01, ITTC's Recommended Procedures and Guidelines: Global Loads Seakeeping Procedure, 2017.
- Oka, M., Hattori, K. & Ogawa, Y., "A realization of hull girder vibration in waves by means of new designed back-bone model," In the 10th Research Presentation Meeting of National Maritime Research Institute, pp.297-298, 2010. (in Japanese)
- Oka, M., Oka, S. & Ogawa, Y., "An experimental study on wave loads of a large container ship and its hydroelastic vibration," Proc. Hydroelasticity in Marine Technology, University of Southampton, UK, pp.183-192, 2009.
- Remy, F., Molin, B., & Ledoux, A., "Experimental and numerical study of the wave response of a flexible barge," In 4th International Conference on Hydroelasticity in Marine Technology, pp.255-264, 2006.
- Sawada, H., Watanabe, I., Yamamoto, T., Tanizawa, K., Ishida, S. Ueno, M. & Miyamoto, M., "On an elastic model to simulate elastic hull responses of ships," Papers of Ship Research Institute, Vol. 24 (2), pp.152-165, 1987. (in Japanese)
- Terazawa, K., "Ship Structural Mechanics (the third edition)," Kaibundo, 1981. (in Japanese)
- Tiphine, E., Bigot, F., De-Lauzon, J., Sireta, F. X., Chung, Y. S., & Malenica, S., "Comparisons of experimental and numerical results for global hydroelastic response of container ship within the WILS III JIP," In The Twenty-fourth International Ocean and Polar Engineering Conference. International Society of Offshore and Polar Engineers, pp.764-773. 2014.
- Waseda, T., Shinchi, M., Nishida, T., Tamura, H., Miyazawa, Y., Kawai, Y., Ichikawa, H., Tomita, H., Nagano, A. & Taniguchi, K., "GPS-based wave observation using a moored oceanographic buoy in the deep ocean," In Proceedings of the Twenty-First International Offshore and Polar Engineering Conference, Maui, HI, USA, pp. 19-24, 2011.
- Wu, Y. S., Chen, R. Z., & Lin, J. R., "Experimental technique of hydroelastic ship model," Hydroelasticity in Marine Technology, pp.131-142, 2003.
- Zhu, S., Wu, M., & Moan, T., "Experimental investigation of hull girder vibrations of a flexible backbone model in bending and torsion," Applied Ocean Research, Vol. 33(4), pp.252-274, 2011. https://doi.org/10.1016/j.apor.2011.08.001