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研究生: 林育聖
Lin, Yu-Sheng
論文名稱: 具翼動角之旋轉Timoshenko樑的動態及穩定分析
Stability and Vibration of a Rotating Timoshenko Beam with a Flapping Angle
指導教授: 李森墉
Lee, Sen-Yung
學位類別: 碩士
Master
系所名稱: 工學院 - 機械工程學系
Department of Mechanical Engineering
論文出版年: 2007
畢業學年度: 95
語文別: 中文
論文頁數: 76
中文關鍵詞: 穩定性翼動角旋轉樑分析方法
外文關鍵詞: flapping angle, stability, analytical method, rotating beam
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  • 具有翼動角的旋轉葉片常是被設計的,但是很少文獻探討翼動角在振動上的影響。本文研究具安置角和翼動角的旋動Timoshenko樑的振動和發散不穩定。利用漢米頓原理推導出旋轉Timoshenko樑的耦合統御微分方程式和其邊界條件。在不考慮軸向伸長和科氏力效應的情況下,當樑的幾何性質和材料性質可以表示成多項式形式,樑的精確解可以求得。
    在本文中,呈現了旋轉Timoshenko樑參數之間的一些簡單的關係式。基於這些關係式,從一已知參數的系統可以預測另一未知系統的自然頻率和參數。並且研究旋轉的發散不穩定(拉伸挫曲)。本文探討了翼動角和其它物理參數對自然頻率的影響和發散不穩定的現象。

    A rotating blade with a flapping angle is usually designed, but little literature investigated the effect of the flapping angle on vibration. This paper investigates divergent instability and vibration of a rotating Timoshenko beam with flapping and setting angles. It uses Hamilton's principle to derive the coupled governing differential equations and the boundary conditions for a rotating Timoshenko beam. Without considering the extension in the axial direction and the Coriolis forces effect , the probles's exact solution can be obtaind if the beam's geometric and material properties can be writtren into polynomial forms.
    Some simple relations among the parameters of a rotating Timoshenko beam are revealed. Based on these relations, one can predict the natural frequencies and the parameters of another system from those of one known system. Moreover, the mechanism of divergent instability (tension buckling) is investigated. Finally, the influences of the flapping angle and other physic parameters on the natural frequencies, and the phenomenon of divergence instability are investigated.

    目 錄 摘要 I Abstract II 誌謝 III 目錄 IV 表目錄 VII 圖目錄 VIII 符號說明 XI 第一章 緒論 1 1.1 前言 1 1.2 文獻回顧 1 1.3研究目的及方向 3 第二章 推導旋轉樑的統御方程式及邊界條件 7 2.1 推導Timoshenko樑之統御方程式及邊界條件 7 2.2 分解統御方程式 10 2.2.1靜態子系統 11 2.2.2動態子系統 12 2.3 推導Bernoulli-Euler樑之統御方程式及邊界條件 13 第三章 無因次化和非耦合化 17 3.1 無因次化參數 17 3.2 Timoshenko樑之無因次化的統御方程式及邊界條件 18 3.2.1翼動角=0之Timoshenko樑 19 3.3 Bernoulli-Euler樑無因次化的統御方程式及邊界條件 19 3.4 統御方程式的非耦合化 20 3.5 均勻Timoshenko樑之無因次統御方程式 23 3.6 非均勻Bernoulli-Euler樑之無因次統御方程式 24 第四章 解法 25 4.1非均勻樑之統御方程式及頻率方程式 25 4.2閉合正規化基本解 28 4.3改良型閉合正規化基本解 29 第五章 數值結果與討論 33 5.1數值比較 33 5.2參數之間的關係式 34 5.3機構的不穩定 37 5.4數值結果與討論 39 第六章 結論 64 參考文獻 66 附錄 70 自述 76 表目錄 表5.1a 旋轉均勻懸臂Timoshenko樑的前四個無因次自然頻率之一 43 表5.1b 旋轉均勻懸臂Timoshenko樑的前四個無因次自然頻率之二 44 表5.2 旋轉非均勻懸臂Bernoulli-Euler樑的前四個無因次自然頻率 45 表5.3a 預測旋轉非均勻懸臂Timoshenko樑的前兩個自然頻率 46 表5.3b 預測旋轉均勻懸臂Bernoulli-Euler樑的前兩個自然頻率 47 表5.4a 旋轉非均勻懸臂Bernoulli-Euler 樑之頻率關係 48 表5.4b 旋轉均勻懸臂Bernoulli-Euler 樑之頻率關係 49 表5.5 安置角和翼動角對旋轉均勻懸臂樑的前四個無因次自然頻率的影響50 圖目錄 圖1.1 沒有傾任何角度的旋轉樑 5 圖1.2 傾安置角(setting angle)旋轉樑 5 圖1.3 傾翼動角(flapping angle) 旋轉樑 6 圖1.4 同時具安置角(setting angle)和翼動角(flapping angle)旋轉樑 6 圖2.1 旋轉樑的幾何及其座標系統圖 15 圖2.2a 樑的變形位移示意圖(1) 16 圖2.2b 樑的變形位移示意圖(2) 16 圖4.1 解法流程圖 32 圖5.1 旋轉非均勻懸臂樑的不穩定區域 51 圖5.2 旋轉懸臂樑的安置角和臨界翼動角之間的關係 52 圖5.3 在不同翼動角的情況下,輪穀半徑r對懸臂Timoshenko樑的前三個自然頻率之影響 53 圖5.4a 在不同翼動角的情況下,轉速對懸臂Bernoulli Euler樑的前三個自然頻率之影響 54 圖5.4b 在不同翼動角的情況下,轉速對懸臂Timoshenko樑的前三個自然頻率之影響 55 圖5.4c 在不同翼動角的情況下,轉速對懸臂Timoshenko和Bernoulli- Euler樑的第一個自然頻率之影響 56 圖5.5 旋轉懸臂Timoshenko樑的臨界轉速和翼動角之間的關係 57 圖5.6 在不同轉速的情況下,翼動角對懸臂Timoshenko樑的前兩個自然頻率之影響 58 圖5.7 在不同翼動角的情況下,轉動慣量對懸臂Timoshonko樑的前三個自然頻率之影響。 59 圖5.8 在不同翼動角的情況下,安置角對懸臂Timoshenko樑的前三個自然頻率之影響 60 圖5.9a 在不同翼動角的情況下,彈性移動彈簧模數T對懸臂Bernoulli- Euler樑的第一自然頻率之影響 61 圖5.9b 在不同翼動角的情況下,彈性旋轉彈簧模數對懸臂Bernoulli- Euler樑的第一自然頻率之影響 62 圖5.10 Bernoulli Euler樑之前四個自然頻率的模態 63

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