Measurement of Acoustic Emission Signals: Influence of the Couplant
The acoustic emission (AE) technique, whose modern roots are found in the early 50’s, analyses the elastic waves generated into solid materials in a frequency range usually well above the human ears limit. AE are sound waves emitted when abrupt variations occur in the local distribution of strain in a medium. These variations are generally associated with, for example, the growth of fractures, phase transformations and corrosion under various loading conditions. This is why the AE technique can be applied as a non destructive and passive tool in condition monitoring of structures, a typical application being the pressure vessels and piping field. In this paper, after a short summary on wave propagation, the AE is simulated by a pulse generator, acting on a bar and a plate. The aim is to highlight the effects of the sensors positioning on some of the parameters frequently adopted to describe the AE activity, e.g. its amplitude and strength.
L. Garibaldi, C. Surace, K. Holford and W.M. Ostachowicz
A. Fasana and L. Garibaldi, "Measurement of Acoustic Emission Signals: Influence of the Couplant", Key Engineering Materials, Vol. 347, pp. 375-380, 2007