Research on Fatigue Lifetime Prediction of Stator Rubber Bushing Based on Rubber Aged Experiment

With the development of oil and gas exploration and development toward deep wells and ultra-deep wells, higher requirements are put forward for the working performance and service life of screw-drilling tools under the high-temperature environment. The failure of stator rubber bushing causes more than 30 % of screw-drilling tool failures. In this study, we mainly research the fatigue life prediction of rubber bushing under high temperature and high pressure and the influence of eccentricity and interference on fatigue life. Therefore, the uniaxial tensile test and fatigue test of hydrogenated nitrile butadiene rubber after 150°C /24 h ageing are carried out to obtain its mechanical properties and fatigue properties, and the fatigue life of rubber bushing is predicted by establishing the finite element mechanical model and combining it with the fatigue analysis software. The results show that the fatigue failure position of stator bushing is consistent with the theoretical and practical failure position and the error between the predicted fatigue life and the actual fatigue life is about 18.25 %. On this basis, the influence of eccentricity and interference on stator bushing fatigue life is analyzed. Fatigue life of stator bushing decreases with the increase of eccentricity or interference, which is consistent with the fatigue life curve of rubber material. The research results can provide reference for stator engineering application and bushing structure optimization of screw-drilling tools.