本論文研究在6061-T6 鋁合金圓管中央處鑽孔加工成圓孔直徑分別為2、4、6、8 與10 mm 的圓孔管，並透過彎管試驗機進行在五種不同的彎矩控制（ ±700、±600、±500、±400 和±300 N-m）下循環彎曲負載至圓管失效毀損的試驗。根據實驗彎矩-曲率的關係中發現，從第一圈開始，該關係即呈現迴圈的狀態，而隨著循環圈數的增加，迴圈的寬度會漸漸的增加，亦即所測得曲率會隨著循環圈數的增加而漸漸的增加，且越大的圓孔直徑，呈現越寬的迴圈寬度，亦即會有越明顯的曲率變化。根據實驗橢圓化-彎矩的關係中發現，曲線呈現不對稱、棘齒、蝴蝶結、增加的趨勢，而在彎矩的峰值處會產生相對較大的橢圓化值，而最大的橢圓化值則會發生在當圓孔管處於負向彎曲的狀況下，此外擁有較大圓孔直徑的圓孔管，會有較大的橢圓化，反之亦然。根據控制彎矩-循環至失效圈數在雙對數座標的關係中發現，越大的控制彎矩會對應有越小的循環至失效圈數，反之亦然。而當施加相同的控制彎矩時，越小圓孔直徑的圓孔管會有越大的循環至失效圈數。最後，本論文提出了理論公式來描述不同圓孔直徑的6061-T6鋁合金圓孔管在彎曲控制循環負載下的控制彎矩-循環至失效圈數的關係，在與實驗結果比較後發現，本文推導出的經驗公式可合理的描述實驗結果。

In this article, 6061-T6 aluminum alloy tubes were drilled at the center of tubes and processed into round-hole tubes with five different hole diameters of 2, 4, 6, 8 and 10 mm. They were applied at five different controlled moments of ±700, ±600, ±500, ±400 and ±300 N-m under cyclic bending test. The experimental moment-curvature relationship demonstrated a close loop starting from the first cycle, and as the number of cycles increased, the width of the loop gradually increased. However, the ovalization-curvature curves presented asymmetrical and increasing trends when the number of cycles increased. The curves also showed ratcheting and bowtie-like shapes. Although the round-hole tubes with five different hole diameters were tested at five different controlled moments, the controlled moment-number of cycles required to initiate failure relationships on a log–log scale presented five straight lines. Finally, an empirical formulation was proposed for simulating the aforementioned relationship. It is found that the simulation results could reasonably simulate the experimental results.

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