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研究生: 楊立禎
Yang, Li-Chen
論文名稱: 移動Trefftz近似法在二維彈性力學問題分析之應用
Analysis of Two Dimensional Elasticity by the Moving Trefftz Method
指導教授: 王永明
Wang, Yung-Ming
學位類別: 碩士
Master
系所名稱: 工學院 - 土木工程學系
Department of Civil Engineering
論文出版年: 2018
畢業學年度: 106
語文別: 中文
論文頁數: 83
中文關鍵詞: 無元素法Trefftz法H-R變分原理二維彈性力學
外文關鍵詞: Meshless Method, Trefftz Method, Hellinger-Reissner Variational principle, Two-dimensional Elasticity
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  • 本文採用移動Trefftz近似法式結合了無元素法之移動近似及邊界積分法中Trefftz法滿足微分方程求解基底。在本文利用H-R變分原理求得平衡方程式及基底函數配合邊界條件計算求得變數。
    文中分析懸臂梁受剪力、簡支梁受均部荷重、無限板中央裂縫受拉力及無限板中央開孔受拉力等二維彈性力學問題,並且透過不同的佈點方式及不同的基底階數分析配合解析解分析其結果精度及誤差收斂性,驗證此法的可靠性及可行性。
    分析算例後,在利用均勻佈點方式,隨著節點數越多,可有良好的精確性及收斂性,若有應力集中現象,會隨著佈點間距越小,越明顯。均勻佈點與隨機佈點兩者經度相差不大,驗證了本文所使用的方法受到佈點方式之影響不大,並且從誤差表中可發現位移及應力之精確度相近,與一般數值方法中位移精確度往往大於應力精度相比較,本文之數值方法在應力分析上更為精準。
    總結以上幾點結論,本文之移動Trefftz 近似法,在分析二維彈性力學之問題上皆能得到良好的結果精度,為穩定及具有實用性之數值模擬方法。

    In this thesis, we use the moving Trefftz method to analyze the two dimensional elasticity problems. The method is combined with the meshless method and the Trefftz method in the boundary integral equation to satisfy the differential equation. In this paper, the modified H-R variational principle is used to obtain the integral equation relative to the boundary conditions. Using the bases that satisfy the equilibrium equation and by the moving approximation techniques, the numerical solution can be obtained.
    Using this method, we simulate a cantilever beam loaded by the shear force, a simply support beam loaded by the uniform load, an infinite plate with a crack in the middle loaded by the tensile force and an infinite plate with a hole loaded by the tensile force, and we use different point distribution and different order of base function. By analyzing the numerical results with the exact solution and comparing the accuracy and error convergence of the results, we can verify the reliability and feasibility of this method.

    摘要 I Abstract II 誌謝 X 目錄 XI 表目錄 XIII 圖目錄 XIV 第一章 緒論 1 1.1前言 1 1.2文獻回顧 2 1.3研究方法 4 1.4文章架構 5 第二章 二維彈性力學H-R變分原理 6 2.1 二維彈力假設 6 2.2 H-R變分原理 7 2.3 邊界條件之矩陣表示式 10 第三章 數值方法理論推導 11 3.1 基於Hellinger-Reissner變分原理的移動近似法 11 3.1.1多項式函數線性微分運算之矩陣表示法 11 3.1.2滿足局部平衡方程式之基底 13 3.1.3 移動近似法 14 3.2 鄰近點的求取 20 3.3 影響半徑 20 3.3 加權函數 20 3.4 誤差計算 21 第四章 數值算例 22 4.1 懸臂梁受剪力作用且滿足Timoshenko邊界假設 22 4.2 懸臂梁受拋物線剪力作用 24 4.3 Timoshenko邊界假設下之簡支梁受均布荷重作用 24 4.4 無限板中央水平裂縫上下受均勻拉力作用 26 4.5 無限板中央水平圓孔左右受均勻拉力作用 28 第五章 結論 31 參考文獻 33

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