本文主要係實驗探討具五種不同尖銳凹槽深度(0.2、0.4、0.6、0.8及1.0 mm)的SUS304不銹鋼管在不同曲度速率對稱循環彎曲負載下黏塑性力學行為與皺曲破壞的關係。實驗是透過彎管試驗機與曲度－橢圓化量測器以不同控制曲度與曲度速率來進行實驗及量測再收集資料。從彎矩－曲度關係圖發現，實驗試件在曲度控制下做循環彎曲負載時，皆有發生循環硬化的現象，且隨著循環不斷的加載與卸載，彎矩－曲度曲線迴圈也漸漸穩定。從橢圓化－曲度關係圖觀察，橢圓化隨著循環彎曲的圈數增加，圖形呈現棘齒狀成長，橢圓化到某一極值時，圓管發生皺曲破壞。由曲度－循環至皺曲圈數關係圖來看，控制曲度速率越大時，產生皺曲破壞所需要的循環圈數就越少。若將上述實驗值置於雙對數座標中，可發現五個不同凹槽深度的試件分別在三個不同曲度速率下皆呈現關係近似五條平行的直線，最後，本文參考Shaw 和 Kyriakides【2】，Pan 與 Her【8】及范揚東【14】等人論文中所提出的理論方程式，綜合以提出可以描述在不同尖銳凹槽深度且控制不同曲度速率下做循環彎曲負載時，控制曲度與皺曲破壞圈數的關係理論方程式。再將理論方程式所分析的結果與實驗數據做比較，發現理論分析可以充分描述實驗結果。

This thesis presents the experimental viscoplastic behavior and buckling failure on SUS 304 stainless steel tubes with five different sharp-notched depths (0.2, 0.4, 0.6, 0.8 and 1.0 mm) subjected to symmetric cycling bending test. The experiment used tube bending machine and curvature-ovalization measurement apparatus to control and measure different curvature and different curvature-rate. It can be observed from the experimental moment-curvature curves that all of the tubes have hardened cyclically during the symmetric cycling bending test and become steady after few cycles. As for the ovalization-curvature curve, the ovalization of the tube’s cross-section increases in a ratcheting manner with the number of cycles. When the ovalization reaches a limit, the tube buckles. In addition, from the curvature-number of cycles to produce buckling curve, the larger control curvature rate leads to fewer number of cycles to produce buckling. If the experimental data plot in the log-log scale, for each curvature rate, the aforementioned relationship shows five almost parallel straight lines corresponded to five different notch depths. Finally, this thesis refers the theoretical equations proposed by Shaw and Kyriakides【2】, Pan and Her【8】and Fan【14】, a theoretical formulation was proposed in this thesis to simulate the relationship between the controlled curvature and the number of cycles to produce buckling for any notch depth under any curvature rate. By comparing the simulations with the experimental data, it can be seen that the theoretical formulation can properly simulate the experimental results.

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