Fault Diagnosis And Identification Of Rolling Bears Based On Dynamics Simulation

Rolling bearing is a key component supporting rotor engine.Once the rolling bearing fails,it may directly lead to serious failure of engine equipment.Therefore,it is of great significance to study the dynamic characteristics of bearings under different conditions and identify typical faults of rolling bearings through simulation,so as to carry out in-depth research on on-line monitoring and fault diagnosis of roller bearings.By establishing the mathematical model of rolling bearing vibration,explicit dynamic simulation model,the rolling bearing dynamic characteristics and typical failure frequency are exteacted.Combined with signal analysis,different fault types of rolling bearing are identified.The main research contents are as follows:(1)The mathematical model based on dynamics and kinematics theory of rolling bearing is studied.Considering oil film,ball slip and non-linearity caused by bearing clearance,the dynamic vibration model of rolling bearing is established.At the same time,the element resonator is introduced to simulate the high frequency vibration induced by the bearing element after the failure of the rolling bearing,and the vibration response of the fault bearing is simulated by numerical method.In this paper,the bearing system is simulated under the condition of bearing outer ring fault,and the simulation analysis results are compared with the theoretical calculation values of fault characteristics.The results show that the fault characteristic frequency is obvious.It is also shown in the time-domain and frequency-domain diagrams,which verifies the correctness of the bearing vibration model established in this chapter.(2)In order to study the dynamic characteristics of multiple point defects rolling bearing,this paper considered the contact stiffness and friction and other factors.ANSYS/LS-DYNA was utilized in the study to build the multiple point defects rolling bearing dynamic model.Considering the outer ring as the main research object,this paper primarily studied the dynamic response and the stress distribution of rolling bearing under the situation that the point defects and defects interval angle are different.The result shows that the more failure point the rolling bearing have,the more contact stress it will receive.It will also make the curve of contact stress become more intensive and the Von Mises stress of rolling bearing unit get heavier.Moreover,the simulation acceleration signal of rolling bearing becomes sparse as the fault interval angle gets bigger.This dynamic simulation software can effectively extract the displacement curve of bearing components,the cloud map of Von Mises Stress and the fault feature frequency under the multiple point defects situation.Therefore,the validity of the model can be verified.Meanwhile,this simulation result provides ideas to the further study of the dynamic characteristics of multiple point defects rolling bearing.(3)In the case of such limited conditions,the fuzzy diagnosis method can be used to determine the probability of generating an abnormality,and different faults can be identified indirectly according to the probability feature step-by-step fuzzy diagnostic method based on frequency domain symptom extraction and trivalent logic fuzzy diagnosis theory(TLFD),which is established by combining the trivalent logic inference theory with the possibility and fuzzy theories,is proposed herein.The features for diagnosing a number of abnormal states are extracted sequentially from the measured signals using statistical tests in the frequency domain.The symptom parameters(SPs)that can sensitively reflect the symptoms of the abnormal states are then selected to provide effective information for the discrimination of each state,and the membership function of each state is generated based on the possibility theory using the probability functions of the SPs.The step-by-step fuzzy diagnoses are performed based on the TLFD.This method can be extensively used to diagnose anomalies in various equipment.According to the structural identification index DI,the sensitive characteristic parameters reflecting abnormal state are selected,which can provide effective information for identifying different abnormal states.Finally,using fuzzy theory and membership degree,different faults can be identified and different types of bearing faults can be distinguished.