本文係針對SUS 304 不鏽鋼薄壁管在中央具有橢圓形凹槽的情形，
控制不同對稱曲率循環彎曲負載至皺曲的試驗。實驗試件係採用寬度固定(2.0 mm)，而五種不同深度(0.2、0.4、0.6、0.8 及1.0 mm)的橢圓形凹槽SUS 304 不鏽鋼管，在相同曲率速率下(0.035 m-1/s)做對稱曲率控制的循環彎曲試驗，以求得不同凹槽深度的橢圓化變化量和循環圈數之間的關係。
本文發現橢圓化變化量和循環圈數的曲線大致可分成三階段，起
始、第二及第三階段，而該曲線的趨勢和單軸潛變的應變與時間曲線非常相似。最後，本文修正單軸潛變的Bailey- Norton Law 以描述不同凹槽深度的橢圓化變化量和循環圈數關係的起始及第二階段行為。經由實驗數據與理論分析數據的比較後發現，理論能合理的描述實驗結果。

This paper presents the experimental investigation of the buckling of the SUS 304 stainless steel tubes with elliptical notch subjected to symmetrical curvature-controlled cyclic bending. There are five kinds of different depths of elliptical notch (0.2, 0.4, 0.6, 0.8 and 1.0 mm) with a same width (1.0 mm) of SUS 304 stainless steel tubes. The tube bending machine and curvature-ovalization measurement apparatus were used to
conduct the constant curvature-rate (0.035 m-1/s) cyclic bending test for obtaining the relationship between the ovalization and number of cycles.
It can be observed from the experimental curve of the ovalization and the number of cycles could be divided into three stages, the initial, secondary and tertiary stages. These three stages are very similar to the three stages of uniaxial creep. The Bailey-Norton creep formulation was modified so that it can be used to simulate the curve for the initial and secondary stages. By comparing the theoretical simulation with the experimental data, good agreement between the experimental and theoretical results has been achieved.

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