Research On Isolation And Feature Extraction Method Of Bearing And Gear Compound Fault In Gearboxes

Gearbox is a common rotating mechanical component,which plays an important role in the field of engineering.Its healthy operation is inseparable from the bearings and gears which provide structural support and power transmission.Due to the influence of complex factors and harsh environment,these components are also vulnerable parts of rotating machinery.Once the bearing or gear failure,it is likely to cause damage to the entire mechanical equipment,leading to more serious consequences.When a single fault occurs in a component,it can be regarded as a "single fault" scenario.In fact,because of the correlation between fault spread and structure,"compound fault" scenario occurs more frequently in reality.However,the research of diagnosis method for this scenario has always been the difficulty.Therefore,considering the needs of practical engineering technology,this paper takes the typical compound fault form（the compound fault of gear and bearing inner and outer rings）as the research object,and tries to separate and decouple the compound fault in a variety of ways based on the different characteristics of the compound fault.Specifically,the main research work of this paper is as follows:（1）Research on the preprocessing method of noise control and feature enhancement of gearbox signal: gearbox always works under complex working conditions and strong noise background,so an appropriate preprocessing method is necessary.In this paper,from the perspective of diagnosis,a variety of pretreatment methods are studied and their applicability is evaluated.In particular,this paper presents a method of inversion editing by using the conjugate symmetry of Fourier transform to suppress the noise in the whole frequency band.The results of comparison and verification prove its effectiveness.（2）Research on fault isolation and diagnosis method of meshing resonance characteristics in gear box compound fault signal: This paper takes meshing resonance phenomenon of gear as a breakthrough,and describes the index of resonance frequency band distribution as the separation basis,and carries out positioning,filtering,demodulation and diagnosis in turn.The purpose of this method is to provide a method of separation and diagnosis of bearing and gear compound faults in frequency domain.Simulation analysis and experimental test show its effectiveness.（3）Research on fault isolation and diagnosis method for sparse characteristic of gearbox compound fault signal: the sparsity and difference provided by different component faults are also the characteristics of bearing and gear compound fault.In this paper,an adaptive dictionary free orthogonal matching pursuit method is established.By capturing the possible fault impulses,they are separated and screened in the way of 0-1 programming,so as to realize the final diagnosis.From the point of view of time domain,this method presents a novel method of compound fault isolation and diagnosis by using sparse decomposition.Simulation and experimental results show the effectiveness of the method.