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Title: | 圓柱殼結構受水下爆炸衝擊之動態反應研究 Dynamic response of cylindrical shell structure subjected to underwater explosion |
Authors: | Tsung-Lin Chou 周宗燐 |
Advisor: | 洪振發 |
Keyword: | 圓柱殼結構,水下爆炸,試驗,FEM,DAA, cylindrical structures,underwater explosion,experiment,FEM,DAA, |
Publication Year : | 2005 |
Degree: | 碩士 |
Abstract: | 水下爆炸過程中,掌握艦艇結構可能破損狀況以保持高倖存率為軍用艦艇結構設計的重要工作之一。另外,若能準確預估艦艇結構破損狀況,更為設計攻擊武器的重要參考。在探討水下爆炸對於船體的衝擊分析之前,應先確認分析模式與分析方法的可靠性,因此先以船艦或潛艦的簡化外殼結構為分析與試驗之研究對象,在可掌握的條件下,比較並且評估分析結果的可靠性,同時對近似理論估算結果進行比較,以確認近似估算方法的可用範圍。
本研究選擇接近潛艦比例之圓柱殼結構模型進行小模型水下爆炸對結構衝擊的數值分析與試驗研究。圓柱結構模型的長與直徑之比例取接近潛艦的長寬比,並且考慮具環向加強肋骨之圓柱殼結構狀況,以檢討環向加強肋骨,對於水下爆炸圓柱殼抗爆震能力之影響。 在爆炸試驗的設定上,選定在4m × 4m × 4m水箱內進行90cm × 30cm × 1mm 之具環向加強肋骨圓柱殼結構水下爆炸試驗,並進行相同條件下之數值分析,對於試驗與分析結果進行比較。 分成二種圓柱殼模型進行試驗與分析: a. 環向肋骨加於圓柱殼外部,以1mm厚度汽車用鋼製成。 b. 環向肋骨加於圓柱殼內部,以1mm厚度不銹鋼製成。 試驗過程選擇190cm、100cm、50cm、30cm多種爆炸距離;190cm至50cm之爆炸距離狀況旨在探討圓柱殼之彈性反應;30cm之爆炸距離狀況旨在探討彈塑性動態反應與塑性破壞現象。在爆炸間距為190cm狀況又分10cm與33cm兩種爆炸水深,以比較有無氣泡脈衝影響之衝擊反應。 在配合試驗的FEM模擬分析上,則應用以『改良雙漸進近似模型(Doubly Asymptotic Approximation,簡稱DAA)』理論發展的USA程式,來處理水下爆炸衝擊(包含主爆震波與爆炸氣泡)與流體及固體界面壓力變化之流-固耦合關係,推算結構浸水面的衝擊壓力,再結合LS/DYNA系統,繼續分析圓柱殼結構遭受水下爆炸之衝擊所造成的動態反應。 針對小水箱小藥量之試驗條件檢討試驗環境對試驗結果的影響與量測資料的修正處理,同時針對試驗模型進行水下爆炸之震波壓力估算比較,以確認主爆震波峰值估算之可用性。以修正之量測爆壓值為入射波壓,進行有限元素法分析,比較量測與分析所得之加速度與應變分佈,檢討數值分析之可行性。 The experimental and numerical studies of linear and nonlinear dynamic response of cylindrical shell structures with stiffener rings subjected to underwater explosion in a 4m×4m×4m water tank have been examined in this work. The dimensions of cylindrical structures are Length × Diameter × thickness = 90cm×30cm×1mm. Two models were examined: - cylindrical shell structure with outside stiffener rings made of 1mm mild steel - cylindrical shell structure with inside stiffener rings made of 1mm mild steel The experiments of dynamic response of cylinder subjected to UNDEX were performed with different standoff distances, which were varied from 30cm to 190cm. The standoff from 50cm to 190cm were designed to observe the linear responses, and the standoff 30cm was used to observe the plastic failures of cylindrical structures. The modified measured pressure data were used as incident pressure of shock wave.The numerical analysis for the same experimental model was performed forcomparison. The USA and LS/DYNA software systems were selected as analysis tools. The accelerations and dynamic strains obtained from experiment and numerical analysis were compared. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/35465 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 工程科學及海洋工程學系 |
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