Dynamic Modeling Of Bearing Defects Under The Influence Of Elastohydrodynamic Lubrication

The stability and reliability of mechanical equipment have become increasingly crucial in modern industrial precision and high-speed development.Bearings,as the primary supporting component of rotating machinery,play a critical role in determining the stability and reliability of mechanical systems.However,bearings frequently operate in harsh environments such as high temperatures and high loads,making them more susceptible to failure.Therefore,establishing an effective bearing dynamics model and studying the vibration mechanism of bearings can aid in bearing condition monitoring and fault diagnosis,which is of significant importance in preventing bearing failure accidents,ensuring personnel and equipment safety,and reducing economic losses.This article focuses on deep groove ball bearings and analyzes the impact of elastohydrodynamic lubrication on Hertz contact.It explores the contact relationship between single-point and multi-point defects and the raceway and establishes a dynamic model of deep groove ball bearings.Additionally,the article investigates the dynamic response characteristics of oil film parameters and different location composite defects under various working conditions.The main research work includes:(1)From a mechanistic perspective,the composition structure,failure forms,and failure types of rolling bearings were analyzed.The characteristics of bearing vibration signals under failure conditions were explored.The article introduces the elastic ring theory to simplify the bearing system and clarify the relationship between internal excitations of the bearing.(2)Calculating the contact force between rolling elements and inner and outer rings under the no-defect condition and constructing the contact model under singlepoint defects of the inner raceway,outer raceway,and rolling elements based on Hertz contact theory.The article also considers the coupling of single-point defects and obtains the contact model under composite defects of inner and outer rings,outer ringrolling elements,and inner ring-rolling elements.Additionally,the article considers the influence of time-varying displacement excitation and random sliding and establishes four-degree-of-freedom dynamic models of bearings with single-point and multi-point defects at different positions.(3)The study aimed to investigate the impact of single-point and multi-point defects located at various positions on bearing vibration and their time and frequency domain characteristics in the presence of defects.Furthermore,the research delved into the dynamic response of elasto-hydrodynamic lubrication concerning diverse speed and radial load conditions,and the vibration response of composite defect bearings at different operating conditions.The findings revealed that the composite defect’s vibration signal was a coupling superposition of the single-point defect’s vibration signal.Moreover,the study demonstrated that the oil film thickness exhibited a positive correlation with speed,whereas it displayed a negative correlation with load.Additionally,the amplitude of bearing vibration increased with the rise in speed,load,and defect size.