Analysis On Electromagnetically Acoustic Emission Signals Using Sample Entropy And Wavelet Packet

As a new nondestructive testing technology, the electromagnetically induced acousticemission technique (EMAE) is through loading electromagnetic field on test specimen togenerate acoustic emission, so as to realize damage detection and evaluation of the conductivesheet. It has syncretic advantages of electromagnetic nondestructive testing technology andacoustic emission nondestructive testing technology. As a new widely used method in biomedicalfield, sample entropy (SampEn) applied into the EMAE signal research is a new attempt, for itsapplication in both deterministic systems and random systems, its short data requirement andgood accuracy and anti-interference ability.First of all, based on the study of generate principle of EMAE and taking signalcharacteristics into consideration, this paper designs the capacitance discharging to stimulateEMAE signal. Acoustic emission produced by standard special acoustic emission signalgenerator is collected as a reference for subsequent theoretical analysis.Secondly, based on mastering the principle of sample entropy algorithm, EMAEexperiments and sample entropy calculation have been done. SampEn parameters’ effect andexternal experiment condition changing effect on the results have been discussed. It is concludedthat characteristics criterion for electromagnetic acoustic emission analysis using sample entropy.At last, this paper puts forward the idea that combines wavelet packet with sample entropy.The optimal wavelet packet base is found to use in the signal decomposition, reconstruction andeliminating interference information. Then the entropy of different specimen before and afterwavelet packet filtering is compared. All have laid a good foundation for the use of sampleentropy in the field of EMAE research.