Fatigue Life Analysis and Equal Life Optimization Design of Fluid End of Septuple Fracturing Pump

Abstract To determine the cause of failures phenomenon of fatigue cracks in the crossbore area of septuple fracturing pump 4 inch fluid end, optimal design the fluid end based on the idea of equal fatigue life to reduce non-uniformity and prolong fatigue life. Firstly, the static finite element analysis under 14 design conditions and 1 test condition are calculated, the results fulfill the static strength requirements. Next, based on the static of 14 actual working conditions, find cycle peaks through constant amplitude alternating load, the fatigue life and distribution rule were calculated. Then, increase the single side width increment e to 75mm, non-uniformity between 7 cylinders is reduced from 26.6% to 1.35%, the fatigue life is prolonged by 98.2%. Finally, by parameter optimization of the crossbore fillet radius Ru to 15mm and reducing the distance from the central axis of the suction cylinder to the top 25mm, the non-uniformity of the cylinder 4 is reduced from 20.07% to 7.67%, the fatigue life is prolonged by 40.9%, and it is prolonged by 179.4% totally. The results show that the analysis method by finding cycle peaks can accurately calculate the fluid end fatigue life. The equal fatigue life parameter optimization approach has obvious consult significance for reduce non-uniformity and prolong fatigue life of septuple fluid end.