基于有限元分析的连续油管寿命研究及预测模型

Study and Prediction Model of Coiled Tubing Life Based on Finite Element Analysis

目前针对连续油管的寿命预测研究较少,但在实际的生产中连续油管的突然失效会造成极大安全隐患,急需解决方案。针对此问题,本文使用有限元仿真方法,针对三种规格的CT80连续油管在不同工况下进行有限元分析,得到了连续油管的受力、形变和疲劳寿命。用疲劳试验对有限元分析进行验证,证明了有限元分析的疲劳寿命的准确性。将连续油管的直径、壁厚、内压、弯曲半径参数转化为外壁应变和环向应力,通过数据拟合建立了关于外壁应变、环向应力和疲劳寿命之间的全经验公式,得到连续油管疲劳寿命预测模型。并用试验得出的结果与疲劳寿命预测模型进行比较,误差较小,可用于CT80连续油管的疲劳寿命预测,最后通过疲劳试验得到了连续油管在二级加载下的疲劳寿命模型,该模型可预测油管在第二级载荷下的剩余疲劳寿命。

At present,there are few studies on the life prediction of coiled tubing,but the sudden failure of coiled tubing in actual production has caused great safety risks and urgent solutions.To solve this problem,the finite element simulation method was used to analyze three kinds of CT80 coiled tubing under different working conditions,and the stress,deformation and fatigue life of the coiled tubing were obtained.The finite element analysis was verified by fatigue test,and the accuracy of fatigue life of finite element analysis was proved.The parameters of diameter,wall thickness,internal pressure and bending radius of coiled tubing were converted into outer wall strain and circumferential stress,and the empirical formula between outer wall strain,circumferential stress and fatigue life was established through data fitting,and the fatigue life prediction model was obtained.The experimental results are compared with the fatigue life prediction model,and the error is small,which can be used to predict the fatigue life of CT80 coiled tubing.Finally,the fatigue life model of coiled tubing under the second stage loading is obtained by fatigue test,which can predict the residual fatigue life of tubing under the second stage loading.