Wavelet-transform-based method of analysis for lamb-wave ultrasonic NDE signals

A new acoustic nondestructive method using Lamb waves as a probe is present ed. These waves are generated and received by an ElectroMagnetic Acoustic T ransducer (EMAT). The position of flaws in the structure under test is comp uted from the time of arrival of the main peak of the reflected signal, Due to the noisy nature of the received signal, we use a wavelet transform alg orithm to extract the required time information. The main advantage of such a multi-scale method of signal analysis is to be suitable for peak detecti on problems especially in highly noisy environments. We explain how we proc eed to do the feature extraction, and we propose two methods for reconstruc ting the image of the inspected structure. Results of real-world ultrasonic Lamb waves signal analysis are presented, In addition, to test the noise r obustness of the method, the case of synthetic noisy signals is also treate d.