本文主要針對兩種不同管徑具有五種不同尖銳凹槽深度的SUS 304不鏽鋼管作對稱循環彎曲負載實驗，以探討其力學行為與皺曲損壞的關係。實驗係透過彎管實驗機與曲度-橢圓化量測器來進行實驗數據的控制、量測及蒐集。從實驗彎矩－曲度曲線圖中顯示，在對稱控制曲度循環彎曲負載時，實驗試件皆會產生循環硬化的現象，且經過反覆的加載與卸載後，其迴圈會漸趨於穩定。其次，由實驗橢圓化－曲度的曲線圖發現，橢圓化量會隨著循環彎曲的圈數增加而成棘齒狀的增加，且當橢圓化量增加到某一個臨界值時，圓管便會發生皺曲損壞。此外，由實驗曲度－循環彎曲至皺曲圈數的關係圖可看出，控制曲度與循環彎曲至皺曲圈數成反比的關係。若將上述實驗值置於雙對數座標中可發現，不論圓管管徑大小，五個不同尖銳凹槽深度的試件皆近似為五條幾乎平行的直線。最後，本文參考Lee、Pan和Kuo【9】、陳立銓【16】與林家宇【17】的理論模型，提出一個可以描述不同外徑同時具有不同尖銳凹槽深度SUS 304不鏽鋼管在循環彎曲負載下，控制曲度與循環彎曲至皺曲圈數關係的理論方程式。在與實驗值做比對後發現，理論分析能合理的描述實驗結果。

This thesis investigates the mechanical behavior and buckling failure of SUS 304 stainless steel tubes with two different outside diameter and five different sharp-notched depths subjected to symmetric cycling bending. The tube bending machine and curvature-ovalization measurement apparatus was used to control, measure and collect the experimental data. It can be observed from the experimental moment-curvature curve that the tube exhibits cyclical hardening during the symmetric cycling bending and becomes steady after a few cycles. Secondly, for the experimental ovalization-curvature curve, the ovalization of the tube cross-section increases in a ratcheting manner with the number of cycles. When the tube ovalization reaches to a critical amount, the tube buckles. Besides, it is shown in the experimental curvature-number of cycles curve that the larger control curvature leads to a fewer amount of the number of cycles. If the aforementioned experimental data plot in a log-log scale, no matter circular pipe caliber size, five almost parallel straight lines can be found for five different sharp-notched depths. Finally, by referring the theoretical formulations proposed by Shaw and Kyriakides【2】, Lee et al.【9】, Chen【16】, Lin【17】, a theoretical formulation was proposed to simulate the relationship between the controlled curvature and the number of cycles to produce buckling with notched thin-walled Tubes with different outside diameter. By comparing the theoretical analysis with the experimental data, it is shown that the theoretical formulation can properly simulate the experimental results.

參考文獻

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