The Response and Failure of Local Sharp-cut 6061-T6 Aluminum Alloy Tubes with Different Diameter-to-thickness Ratios Submitted to Cyclic Bending

不同外徑／壁厚比局部切痕6061-T6鋁合金圓管在循環彎曲負載下行為與損壞之研究

Kuo-Long Lee(李國龍) ； Wei-Yi Huang(黃文義) ； Wen-Fung Pan(潘文峰)

《中正嶺學報》 47卷1期 (2018/05) Pp. 27-39

摘要

In this paper, the response and failure of local sharp-cut 6061-T6 aluminum alloy tubes with different diameter-to-thickness ratios submitted to cyclic bending were studied. Three different diameter-to-thickness ratios of 16.5, 31.0 and 60.0 were considered. The experimental moment-curvature relationship rapidly became a steady loop from the beginning of the first bending cycle. Moreover, the cut depth had almost no influence on the moment-curvature relationship. As for the ovalization-curvature relationship, when the number of cycles increased, it exhibited an increasing and ratcheting manner. It was seen that the greater the depth of the cut, the more asymmetrical ovalization-curvature relationship and the greater the increase of the ovalization. Furthermore, for a certain diameter-to-thickness ratio, five unparallel straight lines corresponding to five different cut depths were found for the controlled curvature-number of cycles required to produce failure relationship on a log-log scale. Finally, a theoretical model was proposed in this study for simulating aforementioned relationship. It was found that the experimental and analytical data agreed well.

關鍵字

Local Sharp-cut ； 6061-T6 Aluminum Alloy Tubes ； Diameter-to-thickness Ratio ； Cyclic Bending ； Response ； Failure

並列摘要

本文主要是研究不同外徑／壁厚比的局部尖銳切痕6061-T6鋁合金圓管在循環彎曲負載下的行為及損壞，而所考慮的三種不同外徑／壁厚比包含有：16.5、31.0及60.0。從實驗的彎矩－曲率曲線中顯示，彎矩－曲率關係從第一圈開始即快速呈現一穩定的迴圈，且切痕深度對彎矩-曲率關係幾乎沒有影響。至於橢圓化－曲率關係則隨著循環圈數的增加而呈現棘齒狀的成長，且切痕深度越深時，橢圓化－曲率關係就越不對稱，橢圓化增加就越大。此外，當考慮個別外徑／壁厚比時，五種不同切痕深度在雙對數座標的控制曲率－循環至損壞圈數關係呈現出五條不平行的直線。最後，本研究提出一個理論模式來描述控制曲率-循環至損壞圈數關係，在與實驗結果比較後發現，理論能夠合理描述實驗結果。

並列關鍵字

局部尖銳切痕 ； 6061-T6鋁合金管 ； 外徑／壁厚比 ； 循環彎曲 ； 反應 ； 損壞