Study on rotor dynamic behavior of magnetic liquid double suspension bearing in hydrostatic system failure

Abstract

Magnetic Liquid Double Suspension Bearing (MLDSB) combines electromagnetic suspension with hydrostatic support to improve load-carrying capacity and operational stability. However, failure of an individual hydrostatic support element can destroy the original force balance and induce strongly coupled electromagnetic–hydrostatic transient responses and rotor–stator rub-impact. Existing studies provide limited understanding of this coupled fault behavior, particularly for different hydrostatic failure locations with experimental validation. To address this issue, a three-degree-of-freedom rotor dynamic model incorporating electromagnetic force, hydrostatic supporting force, and nonlinear rub-impact force is established. Three representative failure modes, namely, lower-, upper-, and right-element failures, are investigated, and the effects of liquid-film thickness, coating thickness, bias current, and supply pressure on the rotor dynamic response are analyzed. The results show that the failure location strongly affects the transient response, with lower-element failure producing the most severe rub-impact behavior, followed by upper- and right-element failures. Increasing the liquid-film thickness, coating thickness, and supply pressure intensifies the rub-impact response, whereas increasing the bias current suppresses it. Experimental comparisons of rotor trajectory, electromagnetic force, and hydrostatic force show trends consistent with the simulations, supporting the capability of the proposed model to capture the principal transient characteristics of MLDSB under hydrostatic failure. The results provide a basis for fault diagnosis, parameter optimization, and safe operation of MLDSB systems.