Study On Creep Property And Characterization Of Carbon Fiber Sucker Rod

Carbon fiber sucker rod has the advantages of high strength,high elasticity,good fatigue resistance and corrosion resistance,etc.It is widely used in various deep Wells,ultra-deep Wells,corrosive Wells and other special Wells,and can reduce the accident rate,improve oil recovery efficiency and reduce oil recovery cost.Bad due to the complex application environment on site,through the coil winding will exist in the process of storage,transportation and operation of bending creep,on the carbon fiber sucker rod body damage,resulting in a decline in its mechanical properties and safety accidents,bending creep of the performance impact of the carbon fiber sucker rod is a lack of relevant experiments and research,Therefore,the creep test is designed to study and characterizing the properties of CFRP sucker rods,which has a certain guiding significance for the safe application of CFRP sucker rods.Firstly,two sets of bending and creep tools were designed to simulate carbon fiber sucker rod in coils.Based on the bending and creep tests,four kinds of carbon fiber sucker rod specimens,19-2500,19-3200,22-2500 and 22-3200,were taken as the research objects.The mechanical properties of four kinds of specimens with creep period were obtained by tensile test,bending test and other tests.At the same time,the strain tester was used to measure the bending stress change of carbon fiber sucker rod during the creep process.The finite element model of bending and creep of carbon fiber sucker rod was established by using ANSYS,and the bending stress distribution law of carbon fiber sucker rod was obtained.The bending stress measured by test and the simulated bending stress were analyzed and compared.The comparison results show that the trend and numerical fitting degree are more than 90%,which verifies the accuracy of the finite element model of bending and creep of carbon fiber sucker rod.Based on the verified model,the simulation analysis shows that the coiling diameter should not be less than 2000 mm.Finally,the entropy method was selected as the evaluation method of the creep performance of carbon fiber sucker rods.According to the test data measured after bending and creep of the two kinds of carbon fiber sucker rods with diameter of 2500 mm,the weights and entropy values of each performance evaluation index of the two kinds of carbon fiber sucker rods were calculated.The results show that the creep performance of carbon fiber sucker rod is best reflected by the bending strength,bending stress and apparent shear strength,and the creep performance evaluation model of carbon fiber sucker rod is established to fit the function of 0-90 d and 90-240 d.The results show that the performance of carbon fiber sucker rod decreases linearly during 0-90 d,and decreases sharply in a quadratic curve during 90-240 d.After 180 d,the performance of carbon fiber sucker rod becomes stable.