本文主要針對不同外徑/壁厚比6061-T6鋁合金圓孔管進行純彎曲鬆弛負載的實驗，以探討相關的力學行為，而純彎曲鬆弛的負載是指將圓孔管彎曲至某個固定曲率後，維持該曲率一段長時間。實驗的圓孔管共有四種不同的外徑/壁厚比分別為:30、40、50與60，每種外徑/壁厚比的圓孔管各有不同的圓孔直徑分別為:2、4、6、8與10 mm。本研究以不同的控制曲率對圓孔管進行純彎曲鬆弛負載的實驗，並將實驗的結果繪成圖表包含有:彎矩-曲率、彎矩-時間及橢圓化-時間的關係。從彎矩-時間的關係圖中顯示，純彎曲鬆弛負載會使得彎矩快速的減少後便漸漸趨近於一穩定的量，而從橢圓化-時間的關係圖中顯示，純彎曲鬆弛負載會使得橢圓化些許的增加後便漸漸趨近於一穩定的量，由於橢圓化不會增加，所以圓孔管不會發生任何損壞。最後，本文根據實驗結果彙整後提出相關的理論來描述不同外徑/壁厚比6061-T6鋁合金圓孔管在不同曲率控制純彎曲鬆弛負載下彎矩與時間的關係，並與實驗結果相互比較後可發現，理論可以合理的描述實驗結果。

This paper presents the experiment and theoretical results of round-hole 6061-T6 aluminum alloy tubes under pure bending relaxation. Four different diameter-to- thickness ratio (D/t ratio) of 30, 40, 50, 60 and five different round-hole diameters of 2, 4, 6, 8 and 10 mm were considered. The pure bending relaxation is to bend the tube to a desired curvature and hold that curvature constant for a period of time. During the experiment of pure bending relaxation, the bending moment decreases rapidly with time and becomes a steady value after a short period of time. In addition, the amount of ovalization increases a little with time and becomes a steady value. Due to the constant ovalization caused by the constant curvature under pure bending relaxation, the round-hole 6061-T6 aluminum alloy tube does not break. Finally, a theoretical form was employed in this study in order to describe the relationship between the bending moment and time. Theoretical analysis is compared with the experimental finding, it is shown that the theoretical formulation can reasonably simulate the experimental results.

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