Multi-objective optimization design for dynamic performances of ball bearings considering coupling effect of a rotor system

Considering coupling effects of dynamic performances of rolling bearings and a rotor system, dynamic equations were constructed by using the finite element method, the rolor system contained a shaft, bearings, and discs. The dynamic performances of rolling bearings were calculated with a quasi-dynamic model after the rotor system response reached a stable state. Taking dynamic load, stiffness, and spin-to-roll ratio as objectives, a multi-objective optimization design was developed based on the genetic algorithm NSGA II, the effect of structural parameters on bearing dynamic performances was analyzed. Taking a rotor system supported with ball bearings as an example, the results showed that the dynamic load decreases, radial stiffness increases and spin-to-roll ratio increases when the outer groove curvature radius increases; the dynamic load decreases, radial stiffness decreases and spin-to-roll ratio decreases as the inner groove curvature radius increases; the dynamic load increases, radial stiffness increases and spin-to-roll ratio increases when the diameter of balls increases; the largest effect on the dynamic performance optimization results is inner groove curvature radius; in a high-speed rotor system, in order to obtain better support dynamic performance, the coupling effect of the rotor system should be considered in multi-objective optimization design of its bearings.