The Research On Ultrasonic Non-destructive Testing Algorithm

Many products made of metal or other materials may have surface and internal defects,to insure products' integrity,people tend to use all kinds of non-destructive testing technique for testing and analyzing the defects of products.Common non-destructive testing methods include ultrasonic testing,penetration testing,radiation testing,magnetic particle testing and eddy current testing,ultrasonic testing is widely used due to its high sensitivity,fast and safe.The research of NDT mainly focuses on de-noise algorithm and parameter estimation.Because of ultrasonic signal is a complex,nonlinear and non-stationary time-varying impulse signal,the traditional Fourier transform is only applicable to processing stationary signal,and wavelet transform and Complementary Ensemble Empirical Mode Decomposition(CEEMD)algorithm are suitable for processing such complex signal and achieving good de-noise effect.On the other hand,in the process of research,the mathematical model of gaussian ultrasonic echo with noise is often used to judge the performance of de-noise algorithm.By using this model to estimate the parameters of the signal after de-noise,the accurate mathematical expression can be obtained,which is of great significance for non-destructive testing.Based on the above research,this paper proposes a de-noise algorithm based on CEEMD and wavelet packet,as well as the parameter estimation method based on this.The simulation analysis shows that the de-noise effect of this algorithm is better than the traditional algorithm,and the S/N and RMSE of the signal are significantly improved.In addition,since the envelope of the signal already contains the main parameter information,it can be extracted by the energy operator for parameter estimation.Finally,MATLAB and LabVIEW are mixed for programming.MATLAB nodes are called in LabVIEW to make full use of their advantages to build a visual system.The denoise algorithm studied in this paper is migrated to this system,which has certain engineering application prospects.