橢圓形凹槽圓管在循環彎曲負載下力學行為之ANSYS有限元素分析

Finite Element ANSYS Analysis on Mechanical Behavior of Elliptical-Notched Circular Tubes Subjected to Cyclic Bending

本文是使用有限元素分析軟體ANSYS來分析橢圓形凹槽圓管，在循環彎曲負載下所呈現的力學行為 （彎矩 （M）-曲度 （ê） 及橢圓化 （ΔD/D）-曲度 （ê）關係）。本文分析流程是先以彎管實驗機及曲度-橢圓化量測器，進行無凹槽316L不銹鋼圓管的力學行為的實驗後，將該實驗結果以有限元素ANSYS進行分析，並求得所對應的相關材料參數；隨後建立橢圓形凹槽圓管的ANSYS分析模式，並將求得的材料常數代入有限元素ANSYS的運算架構中，來分析橢圓形凹槽圓管在循環彎曲負載下的力學行為。而圓管的橢圓形凹槽將分析兩種情況，分別為固定凹槽的深度 （橢圓形短軸的長度），但變動凹槽的寬度 （橢圓形長軸的長度）；另一種為固定凹槽的寬度，但變動凹槽的深度。分析的結果顯示，具凹槽的圓管在承受循環純彎曲負載時，圓管橢圓化的大小呈現不對稱的累積成長現象。

The purpose of this paper is to use the finite element software, ANSYS,to analyze the mechanical behavior (the relationship of moment - curvatureand ovalization - curvature) of elliptical-notched circular tubes subjected tocyclic bending. The analysis process is to first test unnotched 316Lstainless steel tube using a tube-bending machine and curvature-ovalizationmeasurement apparatus. Then, using the finite element ANSYS system toanalyze the mechanical behavior, the relative material parameters for thismaterial can also be determined. Next, the finite element ANSYS modelfor elliptical-notched circular tube is built, and the determined material parameters are used in the calculation structure to find the mechanicalbehavior of elliptical-notched circular tubes under cyclic bending. Twosituations of elliptical notch are considered in this study, one is a notch witha fixed depth (length of the short axis of the ellipse) but variable notchwidths(length of the long axis of the ellipse), and the other is a notch witha fixed width but with variable depths. Based on the analysis result,important behavioral trends are deduced.