Dynamic Modeling And Vibration Characteristics Of Deep Groove Ball Bearings With Single And Multi-point Faults

Rolling bearing is a very important basic element in all kinds of mechanical equipment,which can transmit motion and bearing load.The rolling bearing's working performance will affect the efficiency of the whole machine and even cause catastrophic loss.In order to diagnose and identify the early faults of rolling bearings,it is necessary to solve the basic scientific problem of vibration mechanism and vibration response characteristics of the bearings.However,internal composite rolling bearing faults,sliding roller,shaft and bearing and the bearing coupling between motivation,time-varying displacement excitation,the influence of such factors as well as the actual operation of the rolling bearing in frequently at variable speed and variable load conditions,have a direct and great impact on the response characteristics of bearing vibration excitation mechanism and the acknowledge level.Thus,it makes the real-time performance of the rolling bearing modeling and simulation very difficult.The correlation analysis between the shape and length of the initial local defect fault and the bearing vibration impact response is not thorough,which affects the accuracy and reliability of the early fault judgment of the mechanical system to some extent.Therefore,it is of great practical significance to carry out dynamic behavior experiments and theoretical studies on rolling bearings in order to more accurately monitor the health status of bearings and reduce the loss and casualties caused by sudden failures of bearings.Taking deep groove ball bearing as an example,the contact and motion of rolling body are simulated in this paper.Based on Hertz contact theory,the dynamic behavior of deep groove ball bearings was studied,and the nonlinear contact mechanism between various components of the bearings was explored,and the excitation induced by single or multi-point defects on the bearing surface was analyzed.The paper mainly carried out the following research work:(1)Considering rolling body through contact bearing fault zone and the complexity of the movement,the shaft and bearing and deep groove ball bearings to simplify the model of contact between of rolling element bearing fault zone are analyzed in the whole process,with time-varying displacement and time-varying stiffness to describe the motion state of rolling element,established the time-varying displacement and time-varying stiffness incentives and the mathematical relationship of local defect size,explores the defects induced by the coupling relationship between displacement and force of incentives.(2)The dynamic compound model of single and multi-point fault of 4-DOF deep groove ball bearing was established,and the reliability of the dynamic model was verified.The dynamic characteristics of bearing vibration induced by composite faults,excitation between shaft and bearing,excitation by time-varying displacement,excitation by time-varying stiffness and sliding of rolling body are analyzed.(3)The relationship between single failure of bearing inner ring and single failure of outer ring and single failure of bearing inner ring and outer ring at the same time,that is,multi-point failure,is analyzed.(4)The excitation mechanism of local defects on the bearing surface is investigated,and the influence of the size,speed and load of defects on the vibration characteristics of deep-groove ball bearings is revealed within a certain range.The results show that the increase of the size of the defects,the increase of the speed and the increase of the load will increase the vibration amplitude of the composite fault bearing,affect its running state,and then accelerate the failure of the bearing,reduce the service life of the bearing.