φ73.02mm×5.51mm J55NU油管应变疲劳曲线的构建

Constructing the strain fatigue life curve of φ73.02 mm×5.51 mm J55NU tubing

文章以油田较为常用的73 0 2mm× 5 5 1mmJ5 5和N80NU油管作为研究对象 ,分别用四点关联法 ,通用斜率法和ε—N曲线 3参数幂函数公式 3种方法构建应变疲劳曲线 ,通过对 6根油管试样拉—拉疲劳试验与这 3种方法估算的疲劳寿命作对比 ,结果显示ε—N曲线 3参数幂函数公式构建的曲线更接近试验数值。为进一步验证其准确性 ,又进行了 3根73 0 2mm× 5 5 1mmJ5 5NU油管的拉 拉疲劳试验 ,试验值与估算结果较为接近。因此 ,可近似认为该曲线为73 0 2mm× 5 5 1mmJ5 5NU油管的应变疲劳曲线。按此方法 。

mm×5.51 mm J55 tubing was conducted in the laboratory ,i.e. four points relativity,currency slope calculation and a formula of three-parameter power function were used to construct the strain-life fatigue curves.The tension-tension full scale fatigue tests on six tubing specimens.The results show that the curve conducted by the formula of three-parameter power function is closer to the experimental point than that of other two methods.To improve the dependability of this method,full sale fatigue tests on another three tubing are performed.The results accord with the estimated life at well.Analogically,ε—N curves of other tubing can be conducted.