The Mechanical Behavior and Buckling Failure of Sharp-Notched 6061-T6 Aluminum Alloy Tubes under Pure Bending Creep and Relaxation

In this paper, the response of sharp-notched 6061-T6 aluminum alloy tubes subjected to pure bending creep and relaxation are experimentally and theoretically studied. From the experimental result for pure bending creep, the curvature increase with time until the tube buckles. Higher desired moment leads to the higher curvature and ovalization. From the experimental result for pure bending relaxation, the bending moment rapidly decreases with time and becomes a steady value after all. Due to the constant ovalization caused by the constant curvature under pure bending relaxation, the tube does not buckle. Finally, the formulation proposed by Lee and Pan is modified for simulating the initial and second stages of the creep curvature-time relationship under pure bending creep and relaxation moment-time relationship under pure bending relaxation. Through comparing with the experimental finding, the theoretical analysis can reasonably describe the experimental result.

關鍵字

sharp-notched 6061-T6 aluminum alloy tube ； pure bending creep ； pure bending relaxation

並列摘要

本文係實驗及理論分析尖銳凹槽6061-T6鋁合金管在純彎曲潛變與鬆弛負載下的行為。從純變曲潛變實驗結果得知，曲率及橢圓化的值會持續增加直到圓管發生皺曲，且較高的設定彎矩會造成較大的曲率和橢圓化量。從純彎曲鬆弛實驗結果得知，彎矩的值會隨時間快速的減少且最後會呈現一穩定值。由於純彎曲鬆弛的定值曲率造成固定的橢圓化量，所以圓管不會發生皺曲。最後，我們將Lee and Pan所提出的模式加以修改後來描述純彎曲潛變的潛變曲率－時間及純彎曲鬆弛的鬆弛彎矩－時間關係。與實驗結果比較後發現，理論能合理的描述實驗結果。

並列關鍵字

尖銳凹槽6061-T6鋁合金管；純彎曲潛變；純彎曲鬆弛

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