The purpose of this paper is to demonstrate experimentally the feasibility of nondestructive damage detection by an array of piezotransducers embedded or bonded to the surface of a monitored structure. This paper shows the results of experiments with transmission of elastic waves among systems of piezotransducers surface-bonded to two aluminum specimens: a beam and a plate, and embedded in a concrete block. Structural damages were simulated by masses of various magnitudes placed at the surface of tested specimens. Experimental results obtained so far indicate that there is a strong correlation between the size and location of a simulated and actual damage and the character of signals transmitted among piezotransducers. Anomalies in those signals are repeatable and have distinct characters when they are caused by damage and when they are due to other causes. Piezotransducers used in this study were able to produce and receive signals well above the noise level both when surface-bonded to aluminum specimens and when embedded in a concrete block. The anomalies caused by simulated damages were significant enough to be used for training a neural network.
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