| Project/Area Number |
60850083
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
船舶構造・建造
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| Research Institution | Welding Research Institute, Osaka University |
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Principal Investigator |
UEDA Yukio Welding Research Institute, Osaka Univ. Professor, 溶接工学研究所, 教授 (30029037)
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| Co-Investigator(Kenkyū-buntansha) |
MURAKAWA Hidekazu Welding Research Institute, Osaka Univ., Research Instructor, 溶接工学研究所, 助手 (60166270)
FUJIKUBO Masahiko Institute of Technology, Hiroshima Univ., Research Instructor, 工学部, 助手 (30156848)
NAKACHO Keiji Welding Research Institute, Osaka Univ., Research Instructor, 溶接工学研究所, 助手 (10112070)
石浜 高明 センチュリリサーチセンタ株式会社, 部長補
ISHIHAMA Takaaki Century Research Center Corporation, Assistant Manager
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 1986: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1985: ¥4,700,000 (Direct Cost: ¥4,700,000)
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| Keywords | High Strength Steel / Effectiveness of High Strength Steel / Welding Initial Imperfection / Ultimate Strength / Corrosion Margin / Idealized Stiffened Plate Element / HT-factor / HT係数 / 甲板 / 初期たわみ / 残留応力 / 圧壊強度 / 推定法 / 有効初期たわみ係数 / 軟鋼 |
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| Research Abstract |
In this project, a system to evaluate the effectiveness of the high tensile strength steel used for ship structures was developed. The main emphasis was put on deck panel which is attached to longitudinal and transverse members by welding. Welding initial imperfections are observed in such welded structures. Therefore, a systematic procedure to estimate the ultimate strength of panels with welding imperfections is developed. It consists of two stages. In the first stage, the welding imperfections, such as initial deflections and residual stresses, are estimated when the welding conditions are specified. Further, effective coefficient of initial deflection is evaluated theoretically. Then, the ultimate strength of the panels can be estimated by a simple formula in the second stage.
So called HT-factor is commonly used as a measure to indicate the effectiveness of the high tensile strength steel compared to the mild steel. TH-factor is defined as a relative thickness of the high tensile s
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trength steel plate compared to the mild steel plate which has the same ultimate strength. For two kinds of steels, namely HT32 and HT36, the welding initial imperfections of panels with wide range of aspect ratio are estimated using the actual welding conditions. Further, the compressive strength of the panels with these imperfections are evaluated from the forementioned formula to compute the HT-factors.
According to NK rule, 2.5 mm is required as the corrosion margin. HT-factor, which counts for the corrosion margin, can also be computed to evaluate the effectiveness of the high tensile strength steel by following the procedure developed in this project.
However in the case of stiffened plate, the effectiveness of the high tensile strength steel can not be evaluated simply by the HT-factor as in the case of single panels. It requires close study of the collapse mechanism and the ultimate strength of the structures under consideration. To this purpose, an idealized stiffened plate element, which is superior in efficiency compared to ordinary FEM, is developed. Less
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