本研究是以有限元素分析軟體ANSYS 分析SUS304 不鏽鋼橢圓形凹槽薄壁圓管承受對稱曲度循環彎曲負載下的力學行為，其中力學行為包含有曲度、彎矩及橢圓化的相互關係，而橢圓凹槽分為兩種，一種為固定凹槽的深度，並改變凹槽的寬度；另一種為固定凹槽的寬度，並改變凹槽的深度。由有限元素ANSYS 分析結果可以觀察出，在控制固定曲度做循環彎曲負載時，彎矩－曲度曲線圖顯示出，在固定凹槽的寬度，當深度較淺時，達到設定的控制曲度所需施加的彎矩相對於凹槽深度較大的圓管要大的多。但是在固定凹槽的深度，改變寬度時對彎矩－曲度曲線並無太大影響。至於在橢圓化－曲度的曲線圖中顯示，橢圓化會隨著循環彎曲的圈數漸增且呈現對稱棘齒的變化，當橢圓化值增加到某一極限時，薄壁圓管便會發生皺曲破壞。當在固定凹槽寬度且不同深度的情況下，凹槽越深，成長的速度累積橢圓化量較快，而在固定凹槽深度且不同寬度的情況下，不同寬度對橢圓化的變化並沒有太大的影響。

The purpose of this thesis is to use finite element software ANSYS to analyze the mechanical behavior of thin-walled SUS304 stainless steel tubes with elliptic-notched subjected to curvature-controlled symmetric cyclic bending. The mechanical behavior contains the relationship among curvature, bending moment and ovalization. There are two kinds of the elliptic-notch. The first case is the variable depth with a fixed notch-width and the second case is variable width with a fixed notch-depth. It can be observed from the moment-curvature curve of the first case that the magnitude of the moment is larger for the deeper depth than that for the shallow depth. But, the change of the width does not influence on the moment-curvature curve for the second case. As for the ovalization-curvature curve, it can be observed that the ovalization increases in a ratcheting manner with the number of the bending cycle. When the magnitude of the ovalization reaches a critical value, the tube buckles. The accumulation of the ovalization for the first case is much faster for the deeper depth than that for the less shallow depth. However, the change of the width does not influence on the ovalization-curvature curve for the second case.

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