Correlation Study Of Tangential And Normal Friction Vibration In The Running-in Process Of Reciprocating Sliding Friction Pairs

The friction vibration is a physical phenomenon occurred in the process of friction pairs running-in wear when surface asperity collides.It is one of the output characteristics of tribology system,containing tribology information and dynamic information in the process of friction pairs running-in wear.However,the friction vibration is a weak signal with low SNR,thus often submerged in strong background noise,which make it difficult to reflect the change of the wear state,so it is of great importance to realize the recognition and extraction of friction vibration signal.Correlation analysis can be used for signal recognition and extraction.In the process of friction and wear,the surface asperity collisions can simultaneously excite tangential and normal frictional vibrations.The two are homologous signals,and there is a certain connection between them.Therefore,the study of correlation between tangential and normal frictional vibration can provide a new idea for friction vibration identification and extraction.In this paper,the friction vibration signal collected in the running-in wear trials is research object.Based on cross-correlation theory,correlation of frictional vibration signal was studied.The main research contents and conclusions are as follows:Firstly,the friction and vibration signals with no noise are analyzed by using the cross correlation theory.The results show that the tangential and normal friction vibration signals with noise have time delay,and the correlation coefficient is small and the correlation degree is low.Thus,the noise-containing signal does not reflect the homology of tangential and normal frictional vibrations.In order to remove the effects of noise,application of harmonic wavelet packet transform theory to noise reduction of the collected frictional vibration signal,and the signal reflecting the change of wear state of friction plate is extracted,the correlation analysis was carried out,the results show:noise reduction after the tangential and normal friction vibration signal without time delay,mutual relationship is large,high correlation.Thus,the signal after noise reduction by harmonic wavelet packet reflects the homology of tangential and normal frictional vibrations.On the basis of the above research,in this paper,the cross-correlation coefficients of the tangential and normal friction vibration signals at different moments during friction and wear are analyzed,the results show:the correlation coefficient and the friction coefficient of the tangential and normal friction vibration signals show a consistent trend,reflecting the friction from the wear and wear to the stability of the changes in wear and tear.