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研究生: 張昱賢
Yu-Xian Zhang
論文名稱: 二維應變有限元素法理論推導與程式實踐
Formulation and Program Development of Two-Dimensional Strain-Finite Element Method
指導教授: 潘誠平
Chan-Ping Pan
口試委員: 施俊揚
Jun-Yang Shi
林昌佑
Chang-Yu Lin
學位類別: 碩士
Master
系所名稱: 工程學院 - 營建工程系
Department of Civil and Construction Engineering
論文出版年: 2020
畢業學年度: 108
語文別: 中文
論文頁數: 111
中文關鍵詞: 平滑有限元素法線性應變場線性應力場平滑位移場諧和條件
外文關鍵詞: smooth-FEM, linear strain field, linear stress field, smooth displacement, compatibility conditions
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  • 傳統有限元素法直接假設位移場求解,微分後獲得的應變場、應力場存在不連續的跳躍,而位移場也不保證平滑;因此本研究直接假設線性應變場並以積分的方式獲得以應變為未知數表達的位移函數,其中積分產生的積分常數以位移諧和條件解出,最後以最小總勢能原理求解應變未知數。

    本研究先推導出二維平面應力狀態下應變有限元素法之演算流程,編寫程式實踐理論之算法,最後將運算結果視覺化輸出,並創建二維懸臂梁、軸力桿兩種典型的結構,以不同細密程度的網格劃分做收斂性分析,探討該理論的正確性;其成果在軸力桿模型有相當滿意的結果,收斂速度快且精準,懸臂梁模型則僅有在梁長度方向細分才能達到較好的結果,目前推測該方法對諧和要求較嚴苛有過度約束的疑慮。


    Traditional finite element method directly assumes displacement field to solve problem, the stress field and strain field obtained after differentiation have discontinuous gap and displacement field is not ensured to be smooth; Therefore, this research assumes a linear strain field and obtains the displacement field expressed by the strain unknowns from integration, the constant of integration is solved by displacement compatibility conditions and the strain unknowns is solved by principle of minimum potential energy.

    This research derives the algorithms of Strain-FEM from plane stress, program coding practices the theoretical algorithms; finally, output the visualized algorithm results. Thus, create 2D cantilever beam and 2D axial force member these two typical structures, then conduct convergence analysis based on the fineness level of mesh division in order to examine the correctness of the theory. The result gives positive feedback on model of axial force member which shows convergence rate is high and accurate; however, the model of cantilever beam only shows positive result when the length of the beam is subdivided. Currently, it is inferred that the method has more strict requirement of compatibility and has issue of over-constraint.

    1 緒論 1.1研究背景 1.2 研究動機 1.3 研究方法與架構 2 文獻回顧 2.1 傳統有限元素法 2.2 平滑有限元素法 2.3 最小平方原理有限元素法 2.4 一維梁元素假設應變未知數求解 3 二維應變有限元素法 3.1 二維元素假設應變場求解 3.1.1 假設元素線性應變場推導元素位移場 3.1.2 計算積分常數 3.1.3 應力應變關係 3.1.4 拘束條件減少自由度 3.1.5 最小總勢能原理求解未知數 3.2 計算範例 3.2.1 模擬二維懸臂梁 3.2.2 模擬二維軸力桿 4 程式演算流程與成果評估 4.1 程式架構 4.1.1 輸入資料 4.1.2 運算過程 4.1.3 運算結果輸出 4.2 程式演算範例 4.2.1 模擬二維懸臂梁與軸力桿 4.2.2 模擬二維孔洞問題 4.3 成果評估與收斂性分析 4.3.1 二維梁模型 x 方向網格增加收斂性測試 4.3.2 二維梁模型 y 方向網格增加收斂性測試 4.3.3 二維軸力桿模型 x 方向網格增加收斂性測試 4.3.4 二維軸力桿模型 y 方向網格增加收斂性測試 4.3.5 結果檢討 5 結論與建議 5.1 結論 5.2 建議

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    [7] 王丞緯(2018),「應變有限元素法之理論推導與驗證」,碩士論文,國立 台灣科技大學營建工程系,台北。
    [8] 陳建銘(2018),「假設應變場的結構分析」,碩士論文,國立台灣科技大 學營建工程系,台北。

    [8] 陳建銘(2018),「假設應變場的結構分析」,碩士論文,國立台灣科技大
    學營建工程系,台北。

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