Experimental Research Of Compound Fault Diagnosis Of Rotor SystemBased On EMD

As the main part of most mechanical equipment, rotating machinery often appear allsorts of faults, among which the unbalanced rotor and rotor bending often appear.Machinery and equipments that are presence of axises must be rolling bearing, and rollingbearing is also commonly used and prone to failure. In practice, rotating machinery willoften appear a variety of failures at the same time. This situation is more complex so asthat more and more people pay attention to it.Thus, it is of great significance for the normaloperation of the equipment and the production safety to make the accurate diagnosis of thefaults.In rotating machinery system as the research object, it mainly diagnoses the compositefault of rolling bearings and rotor imbalance, the composite fault of rolling bearings and rotorwinding as well as the failure of inner ring and outer ring of rolling bearing and roller faultdiagnosis meanwhile with the theory of wavelet de-noising, the EMD theory and the shockpulsemethodforconditionmonitoring andfaultdiagnosis.Firstly, Simulate all kinds of single faults and compound faults through a comprehensivemechanical fault simulation-Lite, and speeds are seted to1000RPM,1500RPM,2000RPM,2500RPM and3000RPM, then extract the vibration signal from the mechanical faultsimulation-Lite.Secondly, Decomposite the signal after noise reduction with EMD, and with the EMDissues existing for the end effect the paper use the method of the endpoint mirror extension toimprove, then EMD can successfully applies to the diagnosis of complex faults. Solve thepower spectrum of the IMF of the EMD decomposition of containing fault components, andcompare with normal and single fault so as to diagnose the system that there are two kinds ofcompoundfaultat thesametime.For the rolling bearing fault, the paper carries on the preliminary diagnosis with the shockpulse method (SPM), identifying the presence of rolling bearing fault, but the shock pulsemethod can not be sure what part is bearing fault happens, so it need to continue to useMATLAB to calculate spectrum diagram of program. Study the spectrum diagram, diagnose which parts of the rolling bearing fault happened, and separate two kinds of fault in thecompounding fault, and determine each kind of fault respectively, so that the fault diagnosiswasrealized.In theend, Composite rotorunbalanceand rotorwinding to theinner ring fault respectively,then compare with only the inner ring fault cases, and observe its characteristics and trends ofthe curve.Under high speed another fault has obvious effect on the original fault, yet almost hasno effect under low speed, and the difference of vibration amplitude compositing rotorunbalance and rotor for inner race fault is not big, but the effect of compositing rotor imbalanceis more obvious;Make the same comparison with failure of external ring and rolling body, thenexploretherules.