Many structural health monitoring (SHM) applications in use monitor the progress of Lamb waves across a test object in order to detect structural problems, such as cracks and material losses. This study proposes the use of S-transformation techniques to identify the frequency–time domain characteristics and to reduce the noise of the signals at the receiver. Two time domain models, time delay–attenuation (DA) and time delay–attenuation–phase (DAP), are utilized to represent the propagation of Lamb waves in a compact and meaningful model. The parameters of the models are estimated by using genetic algorithm (GA) techniques. The results of the study show that the DA and DAP models work effectively on the simulated and experimental data.
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