本文主要針對相同方向但不同截面多餘圓孔的6061‒T6鋁合金圓孔管試件進行循環彎曲負載實驗，研究圓孔管相關力學行為並進一步探討多餘圓孔與破裂損壞之間的關係，其中鋁合金圓孔管的圓孔直徑為6 mm而不同截面多餘圓孔直徑為2 mm，圓孔管的圓孔的方向在y方向，多餘圓孔的方向為x方向。本研究共有六組多餘圓孔，其所在的截面分別和主圓孔所在的截面距離為0、10、20、30、40及50 mm，其中截面水平距離為0 mm的實驗數據採用朱柏穎[17]的實驗結果。接著，將彎矩與曲率、橢圓化與曲率、控制曲率與循環至損壞圈以及臨界橢圓化與曲率關係的實驗資料彙整，後續透過實驗結果進行理論分析後，進一步提出相關疲勞壽命趨勢的經驗公式，最後，本研究的實驗結果將與所提出的相關經驗公式進行比較。

In the study, the response and failure of 6061-T6 aluminum alloy round-hole tubes with a redundant hole at the same direction and different cross section under cyclic bending is experimentally investigated. The round hole direction of the round-hole tubes is in y-direction and the redundant hole direction is in x-direction. There are six different cross sections for the redundant hole at the horizontal displacements of 0, 10, 20, 30, 40 and 50 mm. This study is divided into two parts, one is experimental testing and the other is theoretical analysis. The comparison between experimental results and theoretical analysis is included.
The experimental moment-curvature curve shows a stable loop from the first bending cycle. The redundant hole at different cross sections has almost no influence on the moment-curvature relationship. As for the ovalization-curvature relationship, the ovalization increases along with the number of bending cycles. When the ovalization of the tube’s cross section reaches to critical value, the round-hole tube failures due to the cracks. Form experimental critical ovalization-controlled curvature relationship and controlled curvature-number of bending cycles required to ignite failure relationship, a higher controlled curvature leads to a higher critical ovalization and lower number of bending cycles required to ignite failure.
Finally, by referring the theoretical formulation proposed by Shaw and Kyriakides [3] and including the factor of the redundant round hole, the theoretical formulations to simulate the relationship between the controlled curvature and number of bending cycles required to ignite failure and relationship between the critical ovalization and controlled curvature. By comparing with the experimental data, the theoretical formulations can properly simulate the experimental results.

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