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題 名 | 簡支矩形嵌板之水下動態反應研究=Dynamic Responses of Submerged Simply Supported Rectangular Plate |
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作 者 | 梁卓中; 張福安; 賴文豪; | 書刊名 | 中國造船暨輪機工程學刊 |
卷 期 | 17:1 1998.02[民87.02] |
頁 次 | 頁21-37 |
分類號 | 444.1 |
關鍵詞 | 水下; 簡支矩形嵌板; 流固藕合; Submerged; Simply supported rectangular plate; Fluid-structure interaction; |
語 文 | 中文(Chinese) |
中文摘要 | 在海事結構、水下載具及其它水下結構物中,大多以嵌板結構為主體,用以承 受靜態荷載及週期性與隨機性之動態荷載。由於流固藕合作用,水下嵌板的動態反應及結 構變形行為,均比空氣中複雜。因此,探討嵌板結構在水下之動態反應,將對海事結構及 船舶結構設計提供極有助益的指引。 水下簡支矩形嵌板之自由振動及強迫振動,在自由振動分析,是以小撓度薄板橫向振 動理論及速度勢理論推導出流固藕合控制方程式,配合簡支邊界條件採用雙傅立葉級數( Double Fourier Series)為振型函數,求解尺寸為1.0x1.0x0.0055m的矩形嵌板之自然 振頻。分析結果顯示,水下簡支方板考慮受平面力、材料黏滯阻尼及附加質量的影響,前 三階振型之自然振頻較空氣中簡支方板振頻平均降低45%。其中,附加質量為影響水下自 然振頻的極重要因素,在未考慮附加質量因素下,第2,3階振型之振頻在水深為0.05m時 會高估11.6%,在水深為0.3m時會高估6.2%。在水深對自由振頻影響方面,當水深小於 0.1m時,自然振穎值降幅最大,水深大於0.3m後,則振頻漸趨於一穩定值。 水下簡支炬形嵌板之強迫振動分析中,是以自由振動分析中推導得到的控制方程式為 基礎,在矩形突加荷載作用下,對彈性嵌板進行暫態反應分析。結果顯示,在水深0. 025m之簡支矩形嵌板承受矩形突加荷載作用,最大撓度發生在時問0.0252秒時,板中央位 置值為0.68928mm(為板厚的0.14倍),並隨時間的增加而遞減。另外,隨著水深的遞增, 最大撓度有遞減的趨勢。 |
英文摘要 | Panel structures are commonly used in marine structures, submersible vehicles and other underwater structures. Due to the fluid- structure interaction, the dynamic responses and deformed behaviors in water vary from those in vacuum. In this study, we examine the free and forced vibration responses of submerged simply supported rectangular panel. For the free vibration analysis of panels, the governing equation of fluid-structure interaction derived from the theory of transverse vibration of thin elastic plates and velocity potential theorem are used to the natural frequencies of submerged simply supported rectangular panel (1.0x1.0x0.005 m). The simply supported boundary conditions adopt the shape function expressed by Double Fourier Series. It is found that the natural frequencies of first three mode shape are approximately 45% lower than in air. In addition, the natural frequencies of 2□ and 3□ modes that are not considered the effect of added mass are 11.6%-6.2% higher than the ones considered the added mass effect. Besides, the natural frequency of each mode decreased with water depth, more so for higher than for lower modes, and tend to approach certain constant values as the depth increase. Based on the governing equation of fluid- structure interaction, the transient behavior of submerged simply supported rectangular panel subjected to rectangular pulse exciting force are discussed. It is shown that the maximal deflection (0.68928 mm) occurred at the center of the submerged panel when time is 0.0252 sec. The maximal deflection of panel tend to decrease in magnitude as water depth increase. |
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