臺灣博碩士論文加值系統

本論文採用理論及數值方法探討圓杯型摩擦攪拌點銲試片的應力強度因子。由於摩擦攪拌銲點具有階層狀結構，無法以文獻中電阻點銲的理論解替代，故本研究採用兩種理論方法及有限元素法進行分析。研究內容可分成三個部份，第一部分參考Chung and Wang的無限階層模型，推導出二階層銲點模型受開裂作用力的結構應力理論解。第二部分根據Kirchoff板殼理論及分段法，將階層間邊界納入計算，推導出改良式模型受開裂作用力的結構應力理論解。將兩組結構應力理論解分別代入Zhang所提出適用於異種材質及不同厚度試片的應力強度因子理論解，取得兩組應力強度因子理論解。第三部分採用胡力方所建立的摩擦攪拌點銲之圓杯型試片模型為基礎，使用有限元素分析取得應力強度因子數值解。最後將三組結構應力及應力強度因子的結果進行比較及分析，提供未來的工程應用需求。

In this paper, the stress intensity factor (SIF) solutions of friction stir spot welds (FSSWs) in circular-cup specimens were studied by theoretical and numerical approaches. The upper sheets of FSSWs have step structures with various geometries; therefore, the analytical SIF solutions for resistance spot welds cannot be used. The structural stress solutions of FSSWs under opening loading conditions were first obtained by the two-step model of Chung and Wang. According to the plate theory and section method, the modified structural stress solutions were proposed. The two SIF solutions for FSSWs were then obtained from the two structural stress solutions and Zhang’s SIF solutions for spot welds with unequal thicknesses. Based on the 3D finite element model of the FSSW circular-cup specimen from胡力方’s work, the numerical SIF solutions were obtained as well. Finally, the analytical and numerical solutions of structural stresses and SIFs were compared and discussed.

目錄
圖目錄
第一章緒論
1-1前言
1-2摩擦攪拌點銲製程簡介
1-3 文獻回顧
1-3-1理論法(Theoretical Method)推導應力強度因子
1-3-2 數值法(Numerical Method)求應力強度因子
1-4 研究動機與目的
第二章理論說明
2-1 線彈性破壞力學(Linear Elastic Fracture Mechanics, LEFM)
2-1-1 應變能量釋放率G
2-1-2 破裂模式
2-1-3 裂縫尖端應力場
2-1-4 應力強度因子K
2-1-5 J積分式 (J-Integral)
2-1-5-1 Jxy理論解
2-1-5-2 J3或JIII理論解
2-2 應力強度因子理論解(Stress Intensity Factor Solutions)
2-2-1 應力強度因子公式
2-3摩擦攪拌點銲之階層圓板模型理論解
2-3-1 Chung and Wang(2002)之階層圓板模型理論解
2-3-2改良式階層圓板模型理論解
2-4均勻圓板模型理論解
2-5階層圓板模型之彎矩應力及剪力理論解
2-6 有限元素分析法
2-6-1 破壞力學之裂縫尖端元素
第三章研究步驟與數值模擬模型
3-1 研究步驟
3-2 研究流程圖
3-3摩擦攪拌銲點之應力強度因子理論解
3-3-1 Chung and Wang之摩擦攪拌銲點之應力強度因子理論解
3-3-2 改良式摩擦攪拌銲點之應力強度因子理論解
3-4 建立摩擦攪拌銲點之有限元素模型
第四章數值結果與討論
4-1 圓杯型摩擦攪拌點銲試片之應力強度因子理論及數值解
4-1-1 上試片第一階板厚tu=100μm
4-1-2 上試片第一階板厚tu=500μm
4-1-3 上試片第一階板厚tu=600μm
4-1-3 上試片第一階板厚tu=700μm
4-1-4 上試片第一階板厚tu=800μm
4-1-5 上試片第一階板厚tu=900μm
4-1-6 上試片第一階板厚tu=500至900μm比較
4-2 圓杯型摩擦攪拌點銲試片之應力理論及數值解
4-2-1 上試片第一階板厚tu=100μm
4-2-2 上試片第一階板厚tu=500μm
4-2-3 上試片第一階板厚tu=1000μm
4-3 綜合討論
第五章結論
5-1 結論
5-2 未來研究方向
符號表
參考文獻

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