本文目的是實驗研究316L 不銹鋼管在循環彎曲負載時的力學行為及皺曲損壞。力學行為包含有：彎矩-曲度的關係及橢圓化-曲度的關係，而皺曲損壞包含有：控制循環曲度-到達皺曲橢圓化的關係及控制循環曲度-循環至皺曲圈數的關係。本研究採用"彎管試驗機\"及\"曲度-桶圓化量測器"來進行測試316L不錯鋼管。從彎矩-曲度的實驗曲線中顯示，在對稱曲度循環彎曲負載時316L不錯鋼管有循環硬化的現象，而經過了一些循環圈數後迴圈會蠻的較穩定。從精圓化-曲度的實驗曲線中顯示，在對稱曲度循環彎曲負載時桶圓化會漸增且呈對稱棘齒的變化，桶圓化會一直增加直到鋼管發生皺曲。從控制循環曲度及循環至皺曲圈數的實驗曲線中顯示，控制循環曲度量越大時，循環至皺曲圈數就越少。此外，雖然所有的測試鋼管有不同的控制的循環曲度量，但鋼管到達皺曲時的精圓化量幾乎是個定值。

The purpose of this paper is to experimentally investigate the mechanical behavior and buckling failure of 316L stainless steel tubes subjected to cyclic bending. The mechanical behavior measured includes: the relationship between the moment and curvature, and the relationship between ovalization and curvature. The buckling failure measured includes: the relationship between controlled cyclic curvature and ovalization at buckling, and the relationship between the controlled cyclic curvature and the number of cycles to produce buckling. It is found from the moment-curvature curve that the 316L stainless steel tube hardens cyclically and becomes steady after a few cycles for symmetric curvature-controlled bending. However, from the ovalization-curvature curve, the ovalization of the tube cross-section increases in a ratcheting manner with the number of cycles. Owing to the progressive accumulation of the ovalization of the tube cross-section during cyclic bending, the tubes buckle eventually. It is also found, from the controlled cyclic curvature-number of cycles to produce buckling curve, that the higher is the controlled cyclic curvature, the fewer the number of cycles to produce buckling. In addition, although the magnitudes of the controlled cyclic curvature are different for all tested tubes, the ovalizations at buckling are approximately the same.