1996 Fiscal Year Final Research Report Summary
Elastic Behavior of a Huge Pontoon-Typed Floating Structure among Waves
| Project/Area Number |
07651142
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
海洋工学
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| Research Institution | Kanazawa Institute of Technology |
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Principal Investigator |
HATTORI Yoichi Kanazawa Institute of Technology, Department of Technology, Professor, 工学部, 教授 (40198768)
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| Co-Investigator(Kenkyū-buntansha) |
FUKASAWA Toichi Kanazawa Institute of Technology, Department of Technology, Professor, 工学部, 教授 (80143171)
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| Project Period (FY) |
1995 – 1996
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| Keywords | huge floating strucuture / wave exciting force / characteristics of dynamic response / amplitude of forced vibration / characteristic mode / characteristic value |
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| Research Abstract |
The purpose of this research is to clarify the dynamic characteristics of huge pontoon-typed floating structures which encounter waves with various wave lengths, wave heights and wave directions.
First a huge floating structure was replaced with a beam on an elastic foundation and the structural response under wave exciting forces was introduced, using mode method, i.e. the amplitude of the displacement of the structure was non-dimensioned and parameters which affect the non-dimensional amplitude were defined.
The natural circular frequency omega of the waves were changed from 0 to 2.8 rad/s with the interval of 0.2 rad/s and the corresponding non-dimensional amplitudes were obtained. The amplitude increases with w until about 0.4 rad / s where the amplitude becomes maximum and then next peak comes at about 2.23 rad/s. Later on many peaks are seen with small intervals which correspond to natural circular frequencies of the structure.
The mode method needs many terms to be superposed, because the length of the structure is so long and its natural circular frequencies of the structure are arranged with small intervals. Comparing with the results of direct method which were introduced by Suzuki et al, about 100 terms are needed within the range below natural circular frequency of heaving but much more terms become necessary at the range of higher natural circular frequencies.
On the other hand the huge floating structure was replaced with a rectangular plate and natural modes were obtained by finite element method. There are two kinds of natural modes ; one is the mode with no change toward breadth direction which corresponds to the mode of a beam and the other is the twisting mode. The natural circular frequencies of the former mode obtained by finite element method show good agreement with those obtained by replacing the structure with a beam on an elastic foundation.
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Research Products
(2 results)
