艦船結構水下爆炸噴流撞擊之結構動態反應研究

STUDY ON DYNAMIC RESPONSE OF SHIP STRUCTURE SUBJECT TO UNDERWATER EXPLOSION WATER JET IMPACT

水下爆炸通常有兩個主要階段，分別為爆震波（Shock wave）與氣泡脈動（Bubble pulsation）。在氣泡脈動階段，氣泡在收縮與膨脹過程中，加上水的浮力作用下，伴隨發生上浮運動，最後產生高速噴流現象。高速噴流對水面的船體結構具有一定的損傷程度，故在水下爆炸後船體結構的整體效應分析，必須將高速噴流效應之影響納入考量。本論文以水下爆炸產生高速噴流為研究對象。利用ABAQUS有限元素軟體為工具，運用CEL（Couple Eulerian-Lagrangian）理論，首先以Ramajeyathilagam和Vendhan[10]平板在受水下爆炸衝擊變形之實驗結果進行驗證；並以某型船艦為對象，探討船體結構在承受高速噴流，以130 m／s及170 m／sec不同噴流速度，撞擊船體底部中心，探討不同噴流速度下，船體結構最大von-Mises應力、變形量、塑性應變與不同位置von-Mises應力歷程；本論文研究之成果可提供船艦結構設計者進行船體結構設計時使用。

Underwater explosions usually have two main stages, namely shock wave and bubble Pulse. During the bubble pulsation phase of the bubble, the bubble is in the process of contraction and expansion, plus the buoyancy of the water, accompanied by the floating motion, and finally causes a high-speed water jet phenomenon when it collapses. The high-speed water jet caused by bubble collapse has certain damage to the ship structure on the water surface. Therefore, the analysis of the overall effect of the ship structure after underwater explosion must take into account the impact of the bubble collapse on the high-speed water jet effect. This paper takes the high-speed water jet effect caused by bubble collapse as the research object. Using the ABAQUS finite element software as a tool, using CEL (Couple Eulerian-Lagrangian) theory, firstly verify the experimental results of the underwater explosion impact plate deformation of Ramajeyathilagam and Vendhan [10]; and study a certain type of ship as the object. The ship structure is subjected to high-speed water jet caused by bubble collapse, with different jet velocity of 130m/s and 170m/sec, im-pacting the bottom center of the ship hull, the maximum von-Mises stress, deformation, plastic strain and the von-Mises stress history at different locations of the ship structure under different water jet velocity are discussed. The results of this paper can be used to provide ship structure designers for ship structural design.