Acoustic Emission testing

Quality monitoring for composite plate bonding

Update time：2010-10-18 17:16　　　 Viewed：次

Using acoustic emission testing technology, based on the acoustic emission wave propagating characteristics and the theory of least squares method to establish the threedimensional braided composite material performance analysis and internal defects locating method. Through the experiment compared the industrial CT scan and acousticemission testing the difference of the two ways to locate damage source show that ae source location accuracy.

For composite materials, different damage forms has its unique signal characteristics and a comprehensive understanding to the characteristics of materials of different forms of signal model is the premise of analyzing the signal wavelet. Different wavelet function has different appropriate levels when decomposing signal, so it is particularly important to choose appropriate wavelet function to conduct multi-resolution analysis.

It is suggested to try to choose wavelet basis function of small frequency in wavelet analysis, so as to ensure good local wavelet transform timefrequency domain analysis ability. The selection of wavelet basis function should be larger similarity with original signals, and it is also one of the hot spot of current research. The choice of scale can be done according to the analysis of the actual signal. The scale is larger, the more precise the frequency division is, but calculation also increases accordingly. Only to choose appropriate wavelet function and wavelet scale, the advantages of wavelet transform signal analysis can be realized. The choice of wavelet function and scale is still a problem needed to be further discussed in wavelet analysis.

Wavelet multiresolution analysis of signal and noise cancellation, often we are not familiar with the timefrequency characteristics of the actual signal . Sometimes can’t completely get rid of the noise in the signal, such as noise signal and AE signal distribution within the scope of the same frequency band can be difficult to noise cancellationMultiresolution decomposition approach to the signals of different frequency components adopt different temporal resolution, but with the increase of the scale parameterthe corresponding spectrum locality of wavelet basis function, so it is difficult to distinguish the wavelet transform close to the frequency components of the signal. A. Velayudham is proposed using wavelet packet transform method for signal filtering. The method can identify and determine the frequency components of signal contains, or don't need to filter out noise frequency components, retain the required signal to achieve the purpose of filtering, to a certain extent, solve the problem of the noise cancellation.

Due to wave reflection and mode change in complex or small structure, the signal is easy to appear mode and speed change in the process of material transmission. For source localization of acoustic emission signal, determining the arrival time of the wave is the key factor of exploring the velocity of wave propagation .
(Editor：admin)

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