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博碩士論文 etd-0808101-202829 詳細資訊
Title page for etd-0808101-202829
論文名稱
Title
水下纜索之振動分析
Vibration Analysis of an Underwater Cable
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
101
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
口試日期
Date of Exam
2001-07-29
繳交日期
Date of Submission
2001-08-08
關鍵字
Keywords
振動、纜索、拖纜系統、繫纜系統、自然頻率
Cable, Vibration, Towed System, Mooring System
統計
Statistics
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The thesis/dissertation has been browsed 5699 times, has been downloaded 2815 times.
中文摘要
摘要

本研究目的在探討纜索結構之流體引致振動,利用纜索特徵值方法與水下三維之動力及運動方法作分析,得兩種不同之理論基礎所評估結構之自然頻率,再將此結構自然頻率和渦漩流動頻率相比較,判斷是否會發生共振或Lock-in現象。
本研究可分成四大部分,第一部分為水下纜索之動力分析,依邊
界條件又可分為拖纜及繫纜系統,討論在海流、波浪、波流交會等不同海況下,最大水平位移量和未達穩定狀況下之最大動態反應振幅。第二部分為線性之纜索特徵值分析得纜索結構之自然頻率。第三部分為兩種理論之比較,利用纜索運動及動力行為分析得纜索上各點之張力,因張力大小和自然振頻有關,故可由所得之張力經由理論公式可反算結構之自然振頻,此結果在和特徵值之結果比較。第四部分主要在計算結構體因和流體有相對運動而產生的渦漩流動頻率,此結果必須和前面第二及第三部分之結構頻率比較,決定是否有可能發生共振或Lock-in現象。




Abstract
Abstract
The object of this study is to investigate the flow induced vibration of cable structures. Two various methods, Eigenvalue method and Cable dynamics method, are used to evaluate, the natural frequencies of structures. Vortex shedding frequencies are introduced in order to compare with the natural frequencies mentioned above. The results determine whether the phenomenon of resonance or Lock-in occur.

This study has four parts. The first part is the dynamic analysis of an underwater cable Depending on the various boundary conditions, the study discusses, the system of towing cable and mooring cable in which the maximum horizontal displacement and the maximum dynamic response amplitude are found in different ocean environment.
The second part is a linear Eigenvalue analysis for natural frequencies of cable structures. The third part compare the results based on the two methods , Cable dynamics and Eigenvalue method. The former obtain tension results that are important to determine the natural frequencies of structures by theoretical formula. The results of natural frequencies from the letter are compared to those in the former. The fourth part is mainly to calculate vortex shedding frequencies resulting in the relative motion between structures and fluid. The final results found in the fourth part are necessary to compare with part three, so as to determine whether the resonance or Lock-in occur.




目次 Table of Contents
目錄
頁次
第一章 緒論………………………………………………………1
1.1 前言………………………………………………………1
1.2 研究主題…………………………………………………2
1.3 文獻回顧…………………………………………………6
2.1理論基礎簡介 ……………………………………………6
2.2 纜索運動方程式…………………………………………6
2.3 水下纜索之三維運動及動力分析………………………9
2.3.1 纜索動方程式 ………………………………………9
2.3.2繫纜統之邊界條件…………………………………13
2.4水下纜索之外力分析……………………………………14
第三章 基礎測試範例 …………………………………………19
3.1纜索特徵值之數值範例…………………………………19
3.1.1有限段均勻質量纜索之收斂性…………………19
3.1.2末端繫重物之單擺運動情形……………………19
3.1.3振態預測模擬結果………………………………20
3.2水下纜索數值範例…………………………………………21
3.2.1纜索在空氣中之運動情形………………………21
3.2.2纜索在水中之運動情形…………………………23
第四章 水下拖纜系統之振動分析 ……………………………31
4.1水下拖纜系統振動之因素及重要性…………………………31
4.1.1數值分析目的…………………………………………31
4.1.2數值分析流程…………………………………………32
4.2纜索結構1描述…………………………………………33
4.2.1纜索結構1之數值分析…………………………34
4.2.2探討纜索結構1動態反應之最大位移量………36
4.3比較末端繫物重之結果……………………………………37
4.3.1纜索結構在WAVE 1之情形 …………………………38
4.3.2纜索結構在WAVE 2之情形 …………………………40
4.3.3探討波流作雙重作用下之情形 ……………………40
4.3.4比較末端繫物重在不同海況下對其之張力之影響…41
4.3.5剪力流之探討…………………………………………42
4.4均勻張力與不均勻張力之探討 ……………………………45
4.4.1探討加入起伏補償器之影響…………………………46
第五章 水下繫纜系統之振動分析 ……………………………72
5.1數值結分析目的 ………………………………………72
5.1.1升導管(Riser)之介紹…………………………72
5.2纜索結構2描述…………………………………………73
5.2.1纜索結構2之數值分析 …………………………74
5.3升導管結構3之描述…………………………………………83
5.3.1升導管結構3之數值分析 ……………………………92
5.3.2升導管結構3之動態反應最大位移量分析…….……..74
5.4 水下結構物之振動分析……………………………………...76
5.4.1結構1之振動分析….………………………………....78
5.4.2結構2之振動分析….………………………………….82
第六章 結論與建議………………………………………….85
6.1 研究內容………………………………………………………85
6.2 研究結果……………………………………………………….86
6.3 未來方向與建議………………………………………………86
參考書目……………………………………………………87






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