Driving shaft fatigue optimization design of Ω type profile twin-screw pumps

Under changeable pumped medium and working environment, the twin-screw pump is prone to be broken by fatigue failures. A structure optimization design model and method of the driving shaft are presented based on response surface methodology and finite element analysis. In this model, the shaft diameter, chamfering degree and the shaft extension of the power end are selected as optimization variables, the limit values of the variables and maximal normal deformation of the spindle are considered as the constraint conditions, and the minimization of the equivalent alternating stress on the dangerous shaft section is taken as the optimization objective so as to improve the shaft fatigue reliability. The optimization results of a case show that the equivalent alternating stress on the dangerous spindle section reduces by 26.2 %, and the maximal normal deformation decreases by 25.2 % compared with the original design. In addition, the infinite life reliability and fatigue safety factors both meet the design requirements.