臺灣大學: 工程科學及海洋工程學研究所李雅榮楊舜涵Yang, Shun-HanShun-HanYang2013-03-272018-06-282013-03-272018-06-282010http://ntur.lib.ntu.edu.tw//handle/246246/252489本文旨在利用動態非線性有限元素數值分析方法，先後針對四邊簡支平板及一貨櫃輪之船艏，探討結構物受衝擊負荷下之動態挫曲極限與行為。 板結構由於具備極佳之承載能力，廣泛應用於各工程領域。本研究之第一階段，主要利用有限元素計算程式ABAQUS探討板結構物之動態衝擊挫曲強度。首先利用各平板理論驗證數值分析之合理性，再探討負荷大小、衝擊時間等各動態因子與挫曲是否發生之關聯性，並設計線性迴歸法及變形一倍板厚法作為結構物受相異形式衝擊負荷時之挫曲強度判斷基準，最後歸結出衝擊力積為結構受衝擊負荷下產生挫曲之關鍵因素。 根據ISSC 1991的調查報告可知，貨櫃輪近年來所發生之船艏結構損傷案件有90％的比例肇因於波浪衝擊負荷，故對於船艏進行動態波擊分析已成為十分迫切且重要之課題。關於船艏結構受波擊負荷之挫曲強度分析，本文採用MSC.所發展之有限元素分析前後處理器及線性、非線性求解器進行數值模擬。其以一艘實際發生挫曲變形現象之貨櫃輪作為樣本船建立有限元素分析模型，並根據勞氏驗船協會（LR）對於波擊力之預估式作為動態衝擊力之基礎負荷，對船艏進行挫曲模態及衝擊挫曲強度之分析。首先探討模型設計及邊界條件差異對於挫曲強度及挫曲模態之影響，接著於動態衝擊挫曲分析中，比較各結構部位之挫曲強度差異性，並評估波擊作用是否對結構造成嚴重之挫曲破壞。最後希望透過本研究之分析成果，作為日後一般平板結構與船艏結構動態衝擊挫曲強度設計之參考依據。The objective of this paper is to analyze the structural dynamic buckling strength of simply supported square plates and container ship bow structures subjected to impact force by using finite element analysis method. The results reveal that impact force integration under impact force-time curve is the most important factor to determine structure dynamic buckling. Plate structure has been widely employed in various areas due to its prominence of high load-bearing ability. In respect of plate structure, finite element software ABAQUS is used to execute the nonlinear dynamic analysis for investigating the dynamic buckling strength. The results of numerical simulation are compared with Kirchhoff-Love plate theory and structure dynamic theory to demonstrate the validity and reliability of the analysis schemes. Two alternative criteria, linear curve fitting method and one-time thickness deformation method, are utilized to determine the critical dynamic buckling strength. The study inspects the influence of impact force parameters on dynamic buckling behavior of plates: force type, peak value, duration time and impact force integration. Finally, the results show that impact force integration is a crucial factor to cause structure dynamic buckling happened. Damages on containership bow structures have happened frequently and the reviewing of ISSC 1991 indicated 90% of the damages were caused by wave impact loads. Therefore, the investigation of bow structure’s response due to impact load is hence becoming very important and the knowledge for improving bow structure design is widely needed. In respect of bow structure, dynamic buckling phenomenon is also discussed in various aspects, such as buckling strength criterion, slamming pressure and duration time. Besides, the software package MSC/Marc is employed to perform the nonlinear dynamic transient analysis for investigating the response of containership’s bow structures; and the impact load value is obtained by using slamming impact loads formula of LR Rules. Buckling mode, nonlinear buckling deformation and stress distribution were assessed for various impact conditions. The results also conclude that model’s difference, force type, duration time and impact force integration are four significant factors of bow structures dynamic buckling strength.32074426 bytesapplication/pdfen-US動態挫曲強度衝擊負荷衝擊時間衝擊力積有限元素分析艏結構structural dynamic bucklingimpact loadduration timeimpact force integrationfinite element methodbow structurethesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/252489/1/ntu-99-R98525012-1.pdf