本文主要針對六種尖銳凹槽深度之 6061-T6 鋁合金管作對稱循環彎曲負載實驗，以探討其力學行為與皺曲損壞關係。透過彎管實驗機與曲度─橢圓化量測器來進行實驗數據的控制、量測及蒐集，從實驗之彎矩─曲度曲線圖顯示，在對稱循環彎曲負載時，實驗試件皆會發生循環硬化現象，且經過反覆的加載與卸載行為後，其迴圈會漸趨於穩定。其次，由實驗之橢圓化─曲度曲線圖發現，橢圓化值會隨著循環彎曲的圈數增加而成棘齒狀增加，且當橢圓化值增加到某一臨界值時，圓管便會發生皺曲損壞。此外，由實驗之控制曲度─循環至皺曲圈數關係圖可看出，控制曲度越大則皺曲損壞圈數越小。且由其雙對數座標關係圖中可發現兩種趨勢，當凹槽深度小於或等於1.0 mm時，控制曲度─循環至皺曲圈數關係呈現近乎平行的直線；而當凹槽深度小於或等於1.2 mm時，控制曲度─循環至皺曲圈數關係則呈現不平行的直線。最後，本文參考 Shaw and Kyriakides【5】、Lee et al.【6】與范揚東【14】論文中所提出的理論方程式，並導入尖銳凹槽深度後提出一個可以描述不同尖銳凹槽深度圓管在循環彎曲負載時，控制曲度與循環至皺曲圈數關係的理論方程式，在與實驗值做比較後發現，理論分析能充分的描述實驗結果。

This thesis investigates the mechanical behavior and buckling failure of 6061-T6 aluminum alloy tubes with six different sharp-notched lengths subjected to symmetric cycling bending. The tube bending machine and curvature-ovalization measurement apparatus were used to control, measure and collect the experimental data. It can be observed from the experimental moment-curvature curve that the tube exhibits cyclical hardening during the symmetric cycling bending and becomes steady after a few cycles. Next, for the experimental ovalization-curvature curve, the ovalization of the tube cross-section increases in a ratcheting manner with the number of cycles. When the tube ovalization reaches to a critical amount, the tube buckles. In addition, it is shown in the experimental controlled curvature-number of cycles to buckling failure relationship that the larger controlled curvature leads to a fewer amount of the number of cycles to buckling failure. It can be observed from the relationship in a log-log scale that the controlled curvature-number of cycles to buckling failure relationships show parallel straight lines when the notch depth less than or equal to 1.0 mm; However, the controlled curvature-number of cycles to buckling failure relationships show nonparallel straight lines when the notch depth less than or equal to 1.2 mm. Finally, by referring the theoretical formulations proposed by Shaw and Kyriakides【5】, Lee et al.【6】and Fan【14】and including the factor of the sharp-notched lengths, a theoretical formulation was proposed to simulate the relationship between the controlled curvature and the number of cycles to buckling failure. By comparing the theoretical analysis with the experimental data, it is shown that the theoretical formulation can properly simulate the experimental results.

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