Research On Mechanism And Propagation Of Acoustic Emission Signal Of Rolling Bearing With Crack Fault

Acoustic emission signal, as a kind of elastic wave which is released by theinternal energy of materials, has better characterization of the material and theinternal change of the structure compared with vibration signals. Furthermore, it hasits unique advantages for the detection of the early weak fault of rotating machinery,thus acoustic emission technology can be widely used in rotating machinery faultdiagnosis. However, acoustic emission signal, as the basis of acoustic emissiontechnique applied in practice, the study of the generating mechanism and thepropagation characteristics of it is not enough.This paper mainly studies the mechanism of acoustic emission signals, exploresthe generation mechanism of acoustic emission signal in typical faults byestablishing the mathematical model of emission signal in crack fault, puts the finiteelement theory into the propagation simulation of the elastic wave of acousticemission and researches the propagation characteristics of the elastic wave in therolling bearing acoustic emission. Finally, it proves the rationality and the accuracyof fluctuations in the finite element simulation through experiment. The specificwork is as follows:(1) Based on the material mechanics of elasticity and the elastic strain energyrelease theory, this paper studies the rolling bearing outer ring crack extensionenergy of acoustic emission model, gets the rolling bearing crack mathematicalmodel of acoustic emission signal in time domain through the acoustic emissionsignal energy conversion theory and frequency domain transformation theory.(2) Based on the theory of elastic wave, this paper researches the plane wavescattering problem on the outer ring of bearing, puts forward the finite elementtheory applied to elastic wave propagation characteristics of simulation, through thediscretization of the area and the time domain to analyzes the transient wavepropagation characteristics by finite element simulation, studies the same material inthe different structure acoustic emission of elastic wave propagation in different pathattenuation effect and the coupling effect. At the same time, it also proposesdifferent material plate and plate with crack into acoustic emission elastic wavefinite element analysis, using the finite element fluctuations simulation to verify thematerial and the structural properties effect on the propagation characteristics ofacoustic emission signal.(3)Based on the wave theory of elastic wave and the finite element in layeredmedium theory, this paper studies the coupling effect of acoustic emission elasticwave in different medium and the transmission characteristics of interface structure.It uses the finite element fluctuations simulation in layered medium and the sound source localization method to analyze the elastic wave propagation characteristics ofacoustic emission from rolling bearing. It provides theory and simulation foundationfor the efficient collection of acoustic emission signal and its time-frequencyanalysis.(4) Based on the mechanism of acoustic emission signal and the simulation ofelastic wave propagation characteristics, this paper designs testing programs foracoustic emission signal and studies the acoustic emission signal of elastic wavepropagation characteristic through experiments.