Fatigue Life Prediction of Local-dented 6061-T6 Aluminum Alloy Tubes Subjected to Cyclic Bending

局部凹痕6061-T6鋁合金管承受循環彎曲之疲勞壽命估算

Kuo-Long Lee(李國龍) ； Ching-Hsun Meng(孟慶勳) ； Wen-Fung Pan(潘文峰)

《中正嶺學報》 46卷1期 (2017/06) Pp. 39-49

摘要

In this paper, by using adequate stress-strain relationship, models, mesh elements, boundary conditions and loading conditions, the finite element ANSYS Workbench 15.0 was used to analyze the moment-curvature and ovalization-curvature relationships for local-dented 6061-T6 aluminum alloy tubes with dent depths of 0.0, 0.3, 0.6, 0.9 and 1.2 mm subjected to cyclic bending. Once the ANSYS simulations can accurately describe the experimental results, the maximum and minimum stresses for each cyclic bending case can also be accurately obtained. Because the failure type was the fatigue fracture, a simple fatigue model was used to estimate the fatigue life. In addition, due to different amounts between the maximum and minimum stresses, the Walker equation was used for considering the mean stress effect in the fatigue model. It has been shown that the fatigue model can properly predict the fatigue life of local-dented 6061-T6 aluminum alloy tubes with different dent depths subjected to cyclic bending.

關鍵字

Finite Element ANSYS Analysis ； Local-dented 6061-T6 Aluminum Alloy Tubes ； Cyclic Bending ； Moment ； Curvature ； Ovalization ； Stress Amplitude ； Fatigue Model

並列摘要

本文係使用適當的應力－應變關係、模型、網格元素、邊界條件及負載條件，則有限元素ANSYS工作平台15.0可用來分析深度為0.0, 0.3, 0.6, 0.9 and 1.2 mm的局部凹痕6061-T6鋁合金管在循環彎曲負載下的彎矩－曲率與曲率－橢圓化關係。一旦確認ANSYS模擬能準確的描述實驗結果，則每一個循環彎曲負載事件中的最大應力及最小應力即可準確的求得。因為實驗試件的毀損型態是疲勞破壞，因此本文使用一個簡單的疲勞模式來估算疲勞壽命。此外，由於最大應力及最小應力數值上的差異，Walker方程式也利用來考慮疲勞模式中的平均應力影響。分析結果顯示，所提出的疲勞模式能適當的預測不同深度局部凹痕6061-T6鋁合金管在循環彎曲負載下的疲勞壽命。

並列關鍵字

有限元素ANSYS分析 ； 局部凹痕6061-T6鋁合金管 ； 循環彎曲 ； 彎矩 ； 曲率 ； 橢圓化 ； 應力幅度 ； 疲勞模式