Dynamic analysis of an equivalent time-varying stiffness system for local faults of rolling bearing

Here, aiming at the dynamic modeling problem for local faults of rolling bearing, by analyzing changes of each rolling element when entering or exiting load zone and falling into a fault, based on Hertz contact theory, the contact deformation retention factor was defined, the equivalent time-varying stiffness function of rolling bearing was proposed, and a single-DOF time-varying stiffness dynamic model for rolling bearing local fault was established. Theoretical analysis and experimental study were conducted. The study results showed that when rolling elements enter or exit load zone, the number of load-bearing rolling elements in load zone increasing or decreasing can cause small increase or decrease in equivalent time-varying stiffness of the system; when a rolling element falls into a fault, its effective contact stiffness decreases to different levels due to different contact deformation retention factors to cause decrease in equivalent time-varying stiffness of the system; variation of the system' s equivalent time-varying stiffness can cause changes to different levels in contact deformation and contact force of other rolling elements in load zone so that external radian load is balanced, rolling elements near load zone center are affected more obviously, but effective contact stiffness of each rolling element is not affected; the system' s equivalent time-varying stiffness having a sudden change can cause system vibration; during outer ring failing, equivalent time-varying stiffness varies constantly; during inner ring failing, variation of equivalent time-varying stiffness is modulated by rotating of inner ring and has different amplitudes; the proposed single-DOF time-varying stiffness dynamic model is more in line with reality. © 2024 Chinese Vibration Engineering Society. All rights reserved.