Force analysis and fatigue life evaluation of oil well pump valve cover

In the beam pumping system, the broken valve cover of the oil well pump frequently leads to oil well failure. This paper examined the alternating load of the oil well pump valve cover and predicted its fatigue life. First, the fluid-structure coupling simulation model of valve ball motion was established through the fluid dynamics simulation software Fluent to investigate the velocity of the valve ball impacting the valve cover. Based on the simulation results about the impact velocity of the valve ball, the mechanical model of the valve ball impacting the valve cover was constructed through ANSYS/LS-DYNA software, and the impact stress and change rule of the valve cover were analyzed. Then, the S-N fatigue curve of the common material of the valve cover was experimentally obtained. Based on the impact stress simulation results of the valve cover and the fatigue curve of the common material of the valve cover, the modified Miner's Rule was applied to evaluate the fatigue life of the oil well pump valve cover. The results showed that the impact stress of the valve cover was positively related to the impact velocity of the valve ball, and the fatigue life of the 17-4 PH valve cover was longer than that of other materials. The above results not only provide a theoretical basis for the performance improvement and material selection of the valve cover but also contribute to the optimization of production parameters of the oil well.