Research On Fault Identification Of Rolling Bear In Rotating Fluid Machinery

Rotational fluid mechanics has been spread applied in various fields including municipal water conservancy,petrochemical,agriculture,electric power and national defense.Rolling bearing,as an indispensable internal supporting rotating element,plays an important role in the normal operation of rotating fluid machinery system.Fatigue,wear and corrosion and other failures in different forms and degrees will appear in the complex and changeable mechanical system and working environment,affecting the whole operation.SKF6304 bearing was selected as the research object in this research.Explicit dynamics simulation was applied to analyse the bearing fault;meanwhile,the fault simulation experiment was conducted to verify its similarity with the simulation.The obtained fault database was utilized to establish the fault diagnosis model,analyzing and comparing the model performance.The specific research content and main research results are as follows:(1)The stress characteristics and vibration characteristics were studied when the inner ring and the rolling element of the rolling bearing were broken.The finite element dynamic analysis models of bearing with inner ring fault and rolling element fault were established by utilizing HyperMesh and ABAQUS/explicit.Based on the Fourier transform analysis and close to the calculated frequency.The results show that the obvious failure frequencies can be found in the intermediate frequency domain of the displacement signals of the two kinds of failures,which is 35.3Hz and 25.7Hz,respectively.The errors are only 0.28%and 0.78%compared with the calculated frequencies of 35.2Hz and 25.5Hz,and there is frequency doubling component.The calculation formulas of the fault bearing frequency are verified,which provides a prior condition for the test.However,the failure frequency cannot be obtained in the speed and acceleration signals,which may be caused by the loss in the differential process.According to the analysis of displacement,velocity and acceleration signals in all directions,the failure frequency is more obvious in the axial direction,followed by the Z direction.(2)The fault simulation test was coducted.Different kinds and degrees of destructive processing were carried out for multiple bearings.Vibration acceleration signals are collected in six directions,including the horizontal,vertical and axial of the driving end and the non-driving end respectively at different speeds.The results show that the failure frequencies of the bearing outer ring,inner ring and rolling element in 1000 r/min are 41.99 Hz,71.27 Hz and 59.57 Hz,respectively,and the calculated frequency of 42,8 Hz,73.7 Hz and 58.5 Hz,respectively.The error is 1.9%,1.9%and 1.8%,respectively.The frequency spectrum of axial vibration signal with Fourier transform can clearly show the fault characteristics,verifying the results of finite element simulation.The characteristics of various fault spectrum were not clear if the fault is minor.On the contract,when the fault is serious,the vibration spectrum will show peak value at the fault frequency and its frequency doubling.(3)The fault diagnosis model was established,Three algorithms were utilized to build fault diagnosis models,including SVM,XgBoost and Vote algorithm.The fault samples came from the experiments.The classification prediction accuracy was 94.9%,100%and 100%respectively.Based on the model evaluation,it was found that the Vote model has significant advantages over the other two models in computing time,accuracy and memory consumption,and can accurately classify the existing faults.