Full Scale Measurements of the Hydro-Elastic Response of Large Container Ships for Decision Support
The overall topic of this thesis is decision support for operation of ships and several aspects are covered herein. However, the main focus is on the wave-induced hydro-elastic response of large container ships and its implications on the structural response. The analyses are based mainly on full sc...
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| Format: | Book |
| Language: | English |
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Technical University of Denmark
2014
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| Online Access: | https://orbit.dtu.dk/en/publications/80015fe7-b181-4e59-97fd-61f330063fe3 https://backend.orbit.dtu.dk/ws/files/103300007/S166_Ingrid_Marie_Vincent_Andersen.pdf |
| Summary: | The overall topic of this thesis is decision support for operation of ships and several aspects are covered herein. However, the main focus is on the wave-induced hydro-elastic response of large container ships and its implications on the structural response. The analyses are based mainly on full scale measurements from four container ships of 4,400 TEU, 8,600 TEU, 9,400 TEU and 14,000 TEU Primarily, strains measured near the deck amidships are used. Furthermore, measurements of motions and the encountered sea state are available for one of the ships. The smallest ship is in operation on the North Atlantic, while the three largest ships are operated on the Europe - Asia route. In the design rules of the classification societies for container ships the minimum design sagging bending moment amidships is larger than the hogging bending moment. Due to their design (full midship section and slender bow and stern sections) and their normal cargo loading condition, container ships are typically operated in a still-water hogging condition (tension in deck and compression in the bottom structure). The wave-induced bending moment is added to the still-water bending moment, which, together with the smaller design hogging bending moment, generally makes the wave-induced hogging bending moment more critical than the sagging bending moment in the operation of container ships. As container ships of today become larger, their natural vibration frequencies become lower and approach the typical encounter frequency with the waves. Together with the relatively high design speed and often pronounced bow flare this makes large container ship more sensitive to slamming and, consequently, the effects of wave-induced hull girder vibrations. From full scale strain measurements of individual, measured hull girder responses in the four container ships, the wave-induced hull girder vibrations are found to increase the vertical bending moment amidships by 100% or more. From the full scale measurements the amplification, due to the hull ... |
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