The Fatigue Analysis for the Pressure Hull of Submarine

潛艦之結構需要具備有抗深水壓、挫曲、抗水下爆震、抗衝擊與抗疲勞破壞之能力，所以壓力殼之耐壓、耐挫曲、耐爆震、耐衝擊以及耐疲勞破壞的能力自然為其設計重點，然而抗壓、抗挫曲、抗爆震與抗衝擊之設計已有初步之結論[1]，故本文以處於變動深水壓力之下，壓力殼之疲勞強度為研究主軸。 潛艦由於任務內容不同，會進行不同深度的浮與潛，藉以隱蔽行蹤，此時壓力殼會不斷承受循環靜水壓，疲勞問題也隨之產生。結構不連續處是發生疲勞損傷的重點區域，是值得關切的焦點。只要取得船體構件材料之S-N曲線、船體構件之實際負荷履歷以及疲勞累積損壞率這三方面的評估資料，即可對壓力殼的疲勞壽命進行合理預估。 參考[1]所建立之德國U-209型潛艦壓力殼數值模型尺寸諸元，針對循環變動深水壓，進行壓力殼應力分析，確認局部應力集中處，鎖定疲勞破壞最可能出現的位置，探討各局部區域所累積之疲勞損傷，以評估壓力殼之疲勞壽命。再進一步比較當壓力殼補強材不存在時，會對壓力殼之使用壽命造成何種影響。從而確認此壓力殼之設計是否滿足一般軍事潛艦的設計需求。The structure of the submarine needs resist deep water pressure, buckle, under water shock, collision and fatigue damage. And the focus of design of pressure hull must have the capability to sustain deep water pressure, buckle, under water shock, collision and fatigue damage; nevertheless, the analysis of deep water pressure, buckle, under water shock and collision had been discussed. So, the aim of this research is to obtain the fatigue strength of submarine pressure hull under deep water pressure in the change. Because of different task, the submarine will go on with float and dive in different depth, use to conceal the whereabouts. When the pressure hull sustain cyclic water pressure, the fatigue problem will appear. The discontinuous place of the submarine structure is the key area of the fatigue damage happened, it is worthy concern. As long as obtain S-N curve, the actual load history and the cumulative damage rule of the submarine pressure hall, the estimate of the fatigue life with pressure hull become possible. Refer to the numerical pressure hull model of U209 Submarine established before. The stress analysis of pressure hall with cyclic water pressure will discuss where the place of local stress concentration occurs most possibly. Make a study of each local area of the cumulative fatigue damage for predict fatigue life of pressure hull. Additionally, when the mend of the man hole in the pressure hull doesn’t exist, it will cause which kind of influence on the fatigue life of pressure hull. To determine whether the design of the pressure hall can satisfy the requirement of a military submarine.目 錄 頁次 摘要………………......................................................................................................... I 目錄................................................................................................................................. III 圖目錄............................................................................................................................. V 表目錄............................................................................................................................. Ⅶ 第一章 序論 1-1. 研究動機...................................................................................................... 1 1-2. 研究方法...................................................................................................... 2 1-3. 文獻回顧...................................................................................................... 3 1-4. 論文架構...................................................................................................... 4 第二章 疲勞基礎理論 2-1. S-N曲線與疲勞限........................................................................................ 5 2-2. 影響疲勞強度之因子.................................................................................. 6 2-3. 雨流計數法………………………….......................................................... 13 2-4. 疲勞損傷法則…………………………….................................................. 16 第三章 壓力殼強度之分析理論 3-1. 問題敘述...................................................................................................... 17 3-2. 圓筒殼理論………...................................................................................... 18 3-3. 數值解析方法………….............................................................................. 22 3-4. ANSYS之數值分析...................................................................................... 26 3-4-1. 基本關係式....................................................................................... 26 3-3-2. 彈塑性力學與增量分析…............................................................... 27 3-5. 模型元素之選用.......................................................................................... 31 第四章 壓力殼強度之實例分析 4-1. 有限元素分析模型...................................................................................... 35 4-2. 計算結果比較…………………………….................................................. 43 4-2-1. 模型可靠性分析………….…………….................................................. 43 4-2-2. 計算結果比較……………………………............................................... 44 4-3. 修改結構尺寸之計算結果..…..…………….............................................. 49 4-3-1. 削減開孔底板補強之計算………………............................................... 49 4-3-2. 同時削減開孔底板補強與環肋之計算................................................... 51 第五章 結論與建議 5-1. 結論……...................................................................................................... 56 5-2. 建議……………………….......................................................................... 57 參考文獻......................................................................................................................... 5