圓筒型結構經撞擊後對疲勞壽命影響研究

THE STUDY FOR THE EFFECT OF FATIGUE LIFE ON THE CYLINDRICAL SHELL STRUCTURE AFTER IMPACT LOADING

圓筒型結構廣泛應用於商業及軍事用途：在商業用途如風能發電之塔柱結構，深海之各式輸送管線、工業高壓管路或是海下水文探查、海底觀光、海底地形資料測繪、海底佈纜、海下救援等之水下載具壓力殼；軍事用途方面如潛艇壓力殼、魚雷或是各式飛彈彈體，均以圓筒殼為主要結構；圓筒殼結構遭遇複雜受力狀況，除靜水壓負荷為重要的負荷，航行操作時船舶互撞、觸礁或潛艇潛行時撞及海床或海下不明物，遭遇水雷攻擊之水下爆震負荷，靜水壓疊加撞擊或水下爆震之壓力負荷，並加上操作運轉期間，環境複雜的往復負荷，對其疲勞壽命會有重大影響，本論文針對圓筒殼承受撞擊時，對疲勞壽命之影響進行研究。
本論文以圓筒型結構為研究標的，考慮撞擊負荷，針對圓筒型結構疲勞壽命之影響進行研究，並配合實驗進行撞擊試驗及材料疲勞試驗，驗證圓筒型結構受撞擊負荷前後之疲勞壽命計算理論及分析工具，對SUS316L鋼板進行撞擊實驗，撞擊高度分別為1.0 m及1.4 m兩種，完成結構動態反應分析。並將撞擊後製作試片進行拉伸試驗及疲勞試驗以獲得材料對應力應變曲線及Coffin-Manson關係式，將所獲得之疲勞參數藉由數值模擬進行驗證分析。並依據上述撞擊及疲勞分析模式，建立一圓筒殼進行承受船型結構物撞擊結構動態反應分析，獲得圓筒殼遭撞擊之歷程概況以及變形量。並探討圓筒殼於撞擊前後對疲勞壽命之影響，其撞擊前（母材）壽限分析為9119次，而受撞1.4 m高度之鋼板為8932次，受撞1.0 m高度鋼板為8850次。承受撞擊後之壽限比未承受撞擊之壽限會減少，分別減少187次及269次。
本論文所獲成果，可協助產業界研製及開發圓筒型結構如風能發電塔柱結構或水下載具壓力殼結構，並建立國內自行研發製造所需基本研究及設計能量。

Cylindrical structures are widely used in commercial and military applications. In commercial use, such as the tower structure of marine wind power generation, deep-sea pipeline, industrial high-pressure pipeline or the use of submersible vehicles to carry out submarine hydrographic exploration, undersea sightseeing, submarine topography mapping, submarine cable, sea rescue etc. For military purposes, such as submarine pressure hulls, torpedoes or various types of missile shells, the main structures are cylindrical shell. Cylindrical shell structures subject to complex stress conditions. In addition to hydrostatic load is an important load, collision with each other and a submarine hit seabed while diving or encountering underwater explosion load caused by a mine attack during operation period. These hydrostatic load superimposed impacts or underwater explosion load, together with the complex repeated operational load can have a significant impact on their fatigue life. The plan is a multi-year project for three years, will consider the effects of fluid-structure interaction (FSI) on the fatigue life of a marine cylindrical shell under impact or underwater explosion loading impact study.
This paper is based on the cylindrical structure as the research target. Considering the impact load, the impact of the fatigue life of the cylindrical structure is studied. And cooperate with the experiment to carry out the impact test and material fatigue test. Verify the fatigue life calculation theory and analysis tools before and after the cylindrical structure is subjected to impact load and underwater explosion. The paper conduct impact tests on SUS316L steel plates. The impact height is 1.0m and 1.4m respectively, and the dynamic response analysis of the structure is completed. After the impact, the test piece is made for tensile test and fatigue test to obtain the material vs. stress-strain curve and the Coffin-Manson relationship. Use numerical analysis to verify and analyze the obtained fatigue parameters. Finally, according to the above-mentioned impact and fatigue analysis model, a cylindrical water model with limited elements is established. Carry out the dynamic response analysis of the structure subjected to impact, obtain the historical overview of the impact of the water carrier on the cylindrical fixed body and observe the amount of deformation. The impact of the circular pillar on the fatigue life before and after the impact is also dis-cussed. The analysis of the fatigue life span before impact (base metal) is 9,119 times, while the impacted height 1.4m steel plate its fatigue life is 8,932 times, and the impacted height 1.0m steel plate its fatigue life is 8850 times. The fatigue life span after the impact was 187 and 269 less than the fatigue life span without the impact, respectively.
The results obtained after the completion of the paper can assist the industry in the research and development of cylindrical structures such as wind power tower column structures or hydrostatic pressure shell structures. And establish the basic research and design energy required for domestic R&D and manufacturing.