The Damage Process Analysis For Bearing Of Commercial Vehicle Transmission Bench Fatigue Test

As the rapid development of the vehicle technology, the transmission as theimportant component of the vehicle powertrain, its reliability of the service lifeis put forward higher requirements; Meanwhile as the deepening of the testingtechnology and signal processing and analysis technology, mechanicalequipment fault diagnosis which based on vibration signal has obtained rapiddevelopment. Above both promote the application of on-line monitoringtechnology in the transmission But because of the complexity and variability ofthe actual working condition, and the empirical of fault diagnosis, the actualapplication effect is poor. So, firstly it should be based on the transmissionsystem, and uses the vibration signal for a certain number of basic research of itskey parts fatigue damage process.In this paper, it uses the related theory of bearing fault diagnosis, andanalyzes the vibration signal of bearing fatigue damage process in thetransmission constant amplitude fatigue test from different aspects. Thus it getsthe failur process of bearing damage and damage reasons, and puts forward theon-line monitoring method of transmission bearing, which provides basic datasupport and effective analysis method for the transmission on-line monitoringThe main research contents and conclusions are as follows:1) The light commercial vehicle transmission bench fatigue test methodsare introduced, which respectively are gearbox fatigue test method, test conditions, the utilization ratio of gear set and the analysis of the fatigue testresults, etc. Through the acceleration sensor respectively in the process offatigue test for the main test box and paternity test box for real-time collecting, itobtains its vibration data in the whole fatigue life, which subsequently providesthe data support for the fatigue failure process analysis based on vibrationsignal.2) The main damage parts are bearings of the main test box and paternitytest box in the process of constant amplitude fatigue test. It mainly aims at thefirst five cycles of fatigue test, and uses the RMS, full band signal envelope andfiltering signal envelope to analyze the fatigue damage process. The analysisresults show that this transmission bearing damages early, mainly caused by thestructure of the third shaft why operating condition of two bearings in outputshaft is relatively poor. Therefore it can make the bearing in a relatively idealworking condition with adjusting the bearing clearance, and strictly controllingthe assembly error, which reduces the impact from the structure and improvesthe fatigue life of bearing.3) For transmission which is relatively complex, its condition monitoringcan make RMS value as one of the main monitoring indicators, as it is sensitiveto bearing fault. If the RMS value increases apparently, it suggests that bearingmay appear a certain degree of damage. Then the bearing fault could be accurateanalysized utilizing the whole band envelope and the filtered signal envelope.