考慮水彈性效應之散裝貨輪頻譜疲勞分析

Spectral Fatigue Analysis with Hydro-elastic effect of Bulk carrier

蔡思潔(Ssu-Chieh Tsai)

指導教授 ： 李雅榮

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.02635

摘要

本文旨在利用頻譜疲勞分析方法，針對船體易產生應力集中區域，探討考慮水彈性之流固藕合波浪外力作用下，對船體結構疲勞損傷及疲勞壽命的影響。
船舶一生航行於海洋中，除了承受海水壓力、貨物重量與船體重量等靜負荷外，亦承受不規則波浪反覆作用之動範圍內，使得船體波振(Springing)現象引起的額外疲勞累積損傷不可忽視。此動負荷會使船體構件產生結構疲勞破壞，特別是近年來隨著船舶輕量化及採用高張力鋼之發展趨勢下，船體自然頻率大幅降低並進入船舶與波浪的遭遇頻率導致因疲勞損傷而發生之船難事件時有所聞，船體疲勞強度亦成為新船結構設計評估重點之一。
本研究將引用水彈性力學理論，藉由已開發之分析軟體，利用模態疊加法計算船體與波浪間交互的水彈性作用，以獲得考量船體整體變形下之波浪負荷，建立水動力學、水彈性力學等理論基礎研究能力。實際之數值計算乃依據法國驗船協會之頻譜疲勞分析基準，以203,000載重噸散裝貨輪為樣本船，針對易發生疲勞損傷區域進行頻譜疲勞分析，評估水彈性力學對船體結構疲勞壽命之重要性並尋求設計改善對策。最後期望透過本研究之分析流程及結果，作為日後評估大型船舶考慮水彈性力學之頻譜疲勞壽命設計的依據。

關鍵字

水彈性力學 ； 短期分布 ； 長期分布 ； 累積損傷法則 ； 疲勞壽命

並列摘要

The purpose of this paper is to explore when the ship forced not only by hydrodynamic but also by hydro-elastic with spectral fatigue analysis method, the influence of fatigue damage as well as fatigue life on the stress concentration area which occurred easily.
In the sailing life, ship will bear not only static pressures from water, weight of cargo and light ship, but dynamic load such as cycle-loading under irregular dynamic wave. These dynamic loads will make ship structure occur fatigue damage, and the extra cumulative fatigue damage caused by ship springing phenomenon can’t be ignored. Recent years, the trend of lightweight design and increased usage of high tensile steel made the hull girder natural frequency significantly reduced, lower enough to vibrate with the wave environment, and getting into the ship and wave encounter frequency. It’s common to hear shipwrecks due to fatigue damage, as a result, the fatigue strength of ship structure become one of the analyzing point in the process of ship design.
In this study, it will use the theory of hydro-elastic (HE) and developed analysis software to calculate the hydro-elastic effect from interaction between ships and wave with mode superposition method. In the analysis process, we develop the theoretical and fundamental research result for hydrodynamics and hydro-elastic calculations. According to the SFA guidance provided by the Bureau Veritas classification society (BV), using 203,000 DWT bulk carrier as the reference ship and to carry out the fatigue damage assessment, finding out the improved-design ways under spectral fatigue analysis.

並列關鍵字

Hydro-elastic ； Shot term distribution ； Long term distribution ； Cumulative damage rule ； Fatigue life

參考文獻

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