On the Failure of Round-Hole Tubes under Cyclic Bending

循環彎曲負載下圓孔管失效之研究

李國龍(Kuo-Long Lee) ； 翁慕理(Mu-Li Weng) ； 潘文峰(Wen-Fung Pan)

《中國機械工程學刊》 40卷6期 (2019/12) Pp. 663-673

摘要

This paper presents an experiment and an analysis for examining the response and failure of round-hole 6061-T6 aluminum alloy tubes with different hole diameters and hole directions subjected to cyclic bending. The moment-curvature response demonstrated an almost stable and closed hysteresis loop from the first bending cycle. The hole diameters and directions had almost no influence on the loop configuration. However, the ovalization-curvature behavior depicted an asymmetrical, ratcheting, and bow trend with the increase in the number of bending cycles, while hole diameters and directions exhibited a strong influence on this relationship. Finally, the finite-element software ANSYS was employed to describe the moment-curvature and ovalization-curvature relationships, and an empirical model was proposed to simulate the relationship between the controlled curvature and the number of bending cycles required to ignite failure. As a result, the experimental and analytical data were found to agree well.

關鍵字

round-hole tubes ； cyclic bending ； failure ； finite element analysis

並列摘要

本文主要是實驗與理論研究不同圓孔直徑與圓孔方向的6061-T6鋁合金圓孔管在循環彎曲負載下的響應及失效。我們發現，從第一個彎曲循環圈數開始，彎矩－曲率關係即呈現一個幾乎穩定且閉合的遲滯迴圈，圓孔的直徑和方向對迴圈的形狀幾乎沒有影響。然而，隨著循環圈數的增加，橢圓化－曲率關係卻呈現非對稱、棘齒與蝴蝶結狀的成長，且圓孔的直徑和方向對該關係有很大的影響。最後，本研究使用有限元素軟體ANSYS來描述彎矩-曲率及橢圓化－曲率的關係，且本研究也提出一個理論模式來描述控制曲率－循環至失效圈數的關係。在與實驗結果比較後發現，理論能夠合理的描述實驗結果。