本文是針對尖銳凹槽深度為0.2 mm的SUS304無縫不銹鋼圓管在不同曲度比下進行的循環彎曲負載實驗，以探討其力學行為與皺曲損壞之關係。由實驗結果的彎矩和曲度關係中顯示，若圓管是承受對稱曲度的循環彎曲負載時，則實驗試件會產生循環硬化的現象。且不論是對稱或非對稱曲度控制的循環彎曲負載，彎矩和曲度關係在經過幾個循環迴圈後會趨於穩定的狀態。其次，由橢圓化和曲度關係中發現，橢圓化量會隨著循環彎曲次數的增加而呈現棘齒狀的成長。且當橢圓化量增加至某一臨界值時，圓管就會產生皺曲損壞。此外，由曲度範圍和循環至皺曲圈數關係中得知，曲度比越接近-0.45者，其曲線就越對稱，且循環至皺曲圈數也就越多。最後，本文參考Kyriakides and Shaw【2】與Pan and Lee【10】的理論模式後，提出一個理論模式可以描述循環彎曲負載下不同曲度比的曲度範圍與循環至皺曲圈數關係。在與實驗值做比較後發現，理論分析能合理的描述實驗結果。

This thesis presents the mechanical behavior and buckling failure of SUS304 stainless steel tubes with a sharp notch depth of 0.2 mm subjected to cyclic bending with different curvature ratios. From the moment and curvature relationship, the cyclic hardening is found if the controlled-curvature of the tube is symmetric. However, the loop of the moment and curvature becomes steady after a few cycles for symmetric or unsymmetric cyclic bending. From the ovalization and curvature relationship, the ovalization increases in a ratcheting manner with the number of cycles. When the magnitude of the ovalization reaches a critical value, the tube buckles. In addition, from the curvature range and number of cycles to produce buckling relationship, more symmetric phenomenon of the curve and more number of cycles to produce buckling can be seen for the amount of the curvature ratio close to -0.45. Finally, by referring the theoretical models proposed by Kyriakides and Shaw [2] and Pan and Lee [10], a new theoretical model is proposed for describing the relationship between the curvature range and number of cycles to produce buckling with different curvature ratios under cyclic bending. By comparing the experimental data with the theoretical result, it is shown that the theoretical analysis can reasonably describe the experimental result.

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