Dynamic Modeling And Size Evolution Of Rolling Bearing With Localized Defects By Finite Element Method

As one of the precision and basic parts in the mechanical system,rolling bearing determines the running condition of the equipment and the machining accuracy of the product.Due to high-speed and cyclic working conditions of the bearing,its raceway surface is prone to localized defects.The defects would cause abnormal vibration of the bearings,and affect the operation and even cause damage and casualties.However,the appearance of the spall in rolling bearing is the end of the useful life.It is the basis of PHM of the bearing to explore the evolution scale and degree of the defect from the response signal.Therefore,based on the finite element?FE?method,a model of rolling bearing with localized defect is established,the response rule in the process of defect size evolution is explored,and a theoretical guidance for bearing fault diagnosis is provided.The investigate contents of this thesis are as following:?1?A dynamic explicit FE model of the bearing with localized defects is established.Taking ER-16k as the research object,utilizing ABAQUS/Explicit,considering the influences of shaft and bearing pedestal,the dynamic explicit FE model of the bearing,shaft and bearing pedestal with localized defects in the outer ring is established by the definition such as material properties,boundary conditions,contact properties and mesh.?2?The results of the FE model are analyzed and verified.The stress of a rolling element at different positions of the defect is analyzed,and the reason why the defect extends along the rolling element movement direction is explained.By changing the depth and width of the defect,the efforts of the size evaluation of the defect on the shaft displacement and the track are investigated.The acceleration of the model is extracted and the correctness of the model is analyzed theoretically.The FE model is further verified by the bearing localized defect experiment,which is a basic guarantee for analyzing defect evolution.?3?The influences of defect depth and defect angle on the vibration response of the model are researched.The vibration acceleration of the system with different defect depth and defect angle is analyzed,and the influence of time-frequency acceleration of defect depth and defect angle is explored.Utilizing the method of spline interpolation and polynomial fitting,the variation trend of the maximum of acceleration in time domain and the maximum of fault characteristic frequency component of acceleration in frequency domain with defect depth and defect angle,as well as its functional relationship are studied.All of these can provide a theoretical guidance for bearing fault diagnosis based on vibration detection.?4?The effects of defect depth,width and angle on contact response are investigated.The contact force between the rolling element and the raceway is extracted under the condition of healthy and different defect sizes bearing.The multi-event process of the rolling element passing the localized defect is described.The change and reason of the contact force of each rolling element are analyzed.Analyzing the contact force of healthy bearing,the angle of bearing load zone is calculated.A description of scf_{defect-health} is proposed to analyzed contact force.The trend of the maximum scf_{defect-health} with the defect depth and width,and the relationship is researched.The stress of the defect edge with different angles is extracted,and the relationship between the defect angle and the maximum stress of the defect edge is analyzed.It proposed a novel idea for judging the scale of bearing defect evolution.