本文主要是模擬不同外徑/壁厚比不同凹槽深度的尖銳凹槽6061- T6鋁合金圓管在承受對稱曲度循環彎曲負載的行為與毀損。在設定適當的幾何尺寸、網格元素數量、邊界條件、負載條件、時間步階與後處理， ANSYS Workbench 16.0可用來分析相關的力學行為(彎矩、橢圓化、應力與應變)。根據ANSYS模擬彎矩-曲率關係顯示，在相同的外徑/壁厚比值時，凹槽深度對關係圖的影響非常小。至於橢圓化-曲率關係顯示，沒有凹槽深度的圓管呈現對稱和棘齒狀增加的變化，而當外徑/壁厚比值越大時或凹槽深度值越大時，橢圓化值成長的越快且越不對稱。將模擬數據結果與實驗結果【16】進行比較後顯示，模擬的分析能合理描述實驗結果。接著，運用ANSYS計算出應力與應變幅度後，再與實驗【16】所求得之疲勞損毀圈的數值，標示於雙對數座標中。由於應變幅度-疲勞損毀圈數在雙對數座標中幾乎收斂於一條直線，因此，本文提出疲勞模式，並根據直線的斜率及截距，求得所對應的疲勞參數值。

In this paper, the finite element software ANSYS Workbench 16.0 is used to analyze the mechanical behaviour of local sharp-notched circular tubes under cyclic bending. The mechanical behaviour includes the moment-curvature and ovalization-curvature relationships. The tube’s dimensions include three different diameter-thickness ratios and five different notch depths. According to the simulation results, the sharp-notched depth increases, the unsymmetrical phenomenon of the ovalization-curvature relationship becomes obvious and the speed of ovalization accelerates. By comparison of simulation and experimental results, the simulation can reasonable describe the mechanical behaviour of experiment. Finally, ANSYS Workbench 16.0 is employed to calculate the magnitude of stress and strain amplitudes. Next, the stress and strain amplitudes and the experimental number of fatigue failure cycles [16] are plotted in double logarithmic coordinates. Because the strain amplitude - the number of fatigue failure cycles relationship in double logarithmic coordinates is almost converged to a regression line, the mode of fatigue failure is proposed in this study. According to the slope and intercept of the straight line, it can be calculated the corresponding material parameters.

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