Applied Research Of Emd In Coupling Faults Of Rotary Machinery Diagnosis

Rotating machinery is the key equipment in industrial fields, and which is usedwidely to electric power, petroleum, metallurgy, aviation and so on. In actual work,rotating machinery often appears a variety of fault at the same time. In this case, vibrationmechanism is more complicated and the diagnosis is more difficult than single fault. Inorder to make the production effectively and worker safe, coupling fault of rotatingmachinery diagnosis is more and more attention by people. The research object of thispaper is rotating machinery system, with considering the complexity of mechanicalcoupling fault, studying on the coupling of rotating machinery fault diagnosis methodbased on EMD, in the meantime, analyzing fault characteristics by application modelingmethod. To overcome the end effects of EMD, A new method is put forward andsuccessfully applied to the coupling fault diagnosis.Based on Similar extreme a extension and Cosine window function Suppressionmethod for end effects was proposed. With the method combining advantages of extensionand window function, the inaccuracy of extension and original signal changed because ofwindow function are optimized, and the precision of EMD is improved.Aiming at coupling faults diagnosis of rotary machinery, Building a rotor-bearingsystem model with coupling faults of crack and rub-impact, meanwhile considering theinfluence of nonlinear oil film force. with Runge-Kutta method Solution of differentialequation is obtained, then IMF containing fault feature is disposed by improved EMD,finally by the Hilbert transformation getting relevant boundary spectrum and Hilbertspectrum. Contrasting with fault feature of single fault, the fault system is diagnosed withboth containing crack and rub-impact,Due to vibration mechanism of system existing three kinds of fault is complex, andnonlinearity of signal is stronger, Only through EMD and the analysis of signal doublingfrequency it is very difficult to make accurate fault diagnosis for system. Aiming at thisthe problem, based on EMD and fractal box dimension method of faults diagnosis isproposed. the method through the first to process fault signal by EMD, than to solve boxdimension of effective IMF, getting coupling fault feature vector, Judging fault state, at last achieve the goal of fault diagnosis.Designing a Coupling of rotating machinery fault diagnosis system based on EMDwith Matlab software. First of all, the system selects signal, then decomposes this signalby EMD, finally analysis signal in time domain, frequency domain, the fractal boxdimension method, getting fault feature and realizing fault diagnosis.