本文利用彎管試驗機對不同圓孔方向(0°、45°、90°、135°、180°)及不同圓孔直徑(2、4、6、8、10 mm)的6061-T6鋁合金圓孔管進行純彎曲潛變的實驗，並觀察潛變曲率、潛變橢圓化與時間之間的相互關係，而純彎曲潛變係指將圓孔管彎曲至一固定彎矩後，維持該彎矩一段長時間。實驗結果顯示，當圓孔管承受純彎曲潛變負載時，圓孔管的曲率及橢圓化會隨時間增加而增加。在相同的圓孔直徑及相同的圓孔方向下，固定彎矩越大時，潛變曲率也就越大；在相同的固定彎矩及相同的圓孔方向下，圓孔直徑越大時，潛變曲率也就越大。由於純彎曲潛變負載會使得圓孔管的曲率與橢圓化持續的增加，圓孔管最終會發生破裂失效。此外，實驗結果顯示，純彎曲潛變負載的潛變曲率-時間曲線可分成三個階段(第一、第二與第三階段)。本研究提出理論模式來描述不同圓孔方向及不同圓孔直徑的6061-T6鋁合金圓孔管在純彎曲潛變負載下，第一與第二階段潛變曲率-時間的關係，再與實驗結果相互比較後發現，理論可以合理地描述實驗結果。

Research goal of this thesis is to understand the effect of different round-hole directions (0°, 45°, 90°, 135° and 180°) and different round-hole diameters (2, 4, 6, 8 and 10 mm) on 6061-T6 aluminum alloy tubes subjected to pure bending creep. Pure bending creep is to bend the tube to the required moment and maintain the moment for long period of time. The tube-bending machine was employed in this research to conduct the experiments and investigate the relationship between tubes’ creep curvature and time.
Experimental results show that the creep curvature of round-hole tubes increase with time. As the curvature continues to increase, the round-hole tubes eventually rupture. The creep curvature-time curve can be divided into three stages. In this research, the primary and the secondary creep stages were only taken into consideration. Consider the same round-hole direction and round-hole diameter, when applying higher holding moment, the tubes will result in higher creep curvature. In addition, when applying same holding moment to round-hole tubes under same round-hole direction, tubes with larger round-hole diameter exhibit higher creep curvature. Furthermore, when applying same holding moment to round-hole tubes under same round-hole diameter, tubes show the highest creep curvature when round-hole direction is 0°, while there will be the smallest creep curvature when round-hole direction is 90°.
Finally, the empirical formulas are proposed to simulate the creep curvature-time relationship for pure bending creep of tubes in the primary stage and the secondary stage. By comparing with experimental results, theoretical formulas can reasonably describe the experimental results.

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