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Application of acoustic emission to monitoring the course of the alkali-silica reaction

Świt G., Zapała-Sławeta J.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2020

Vol. 68, nr 1

169--178

The study presented research on the possibility of using acoustic emission to detect and analyze the development of the alkali-silica reaction (ASR) in cement mortars. The experiment was conducted under laboratory conditions using mortars with reactive opal aggregate, accelerating the reaction by ensuring high humidity and temperature, in accordance with ASTM C227. The progress of corrosion processes was monitored continuously for 14 days. The tests were complemented with measurements of the expansion of the mortars and observations of microstructures under a scanning electron microscope. The high sensitivity of the acoustic emission method applied to material fracture caused by ASR enabled the detection of corrosion processes already on the first day of the test, much sooner than the first recorded changes in linear elongation of the specimens. Characteristic signal descriptors were analyzed to determine the progress of corrosion processes and indicate the source of the cracks. Analysis of recorded 13 AE parameters (counts total, counts to peak, duration, rise time, energy, signal strength, amplitude, RMS, ASL, relative energy, average frequency, initial frequency and reverberation frequency) indicates that the number of counts, signal strength and average frequency provide most information about the deleterious processes that occur in the reactive aggregate mortars. The values of RA (rise time/amplitude) and AF (average frequency) enabled the classification of detected signals as indicating tensile or shear cracks. The acoustic emission method was found suitable for monitoring the course of alkali-aggregate reaction effects.

Lokalizacja źródeł wyładowań niezupełnych w transformatorach olejowych poprzez analizę sygnałów emisji akustycznej w różnych pasmach częstotliwości

Olszewska A.

Przegląd Elektrotechniczny

2010

R. 86, nr 11b

63-65

W pracy przedstawiono wyniki analizy sygnałów emisji akustycznej (EA) pochodzących od wyładowań niezupełnych (wnz) w transformatorze olejowym w różnych pasmach częstotliwości. Do tego celu wykorzystano deskryptory ADP, ADC i ADNC oraz obliczone mapy tych deskryptorów. Na podstawie analizy dokonano lokalizacji źródeł wyładowań niezupełnych w badanym transformatorze olejowym.

Analysis results of acoustic emission (AE) signals coming from partial discharges in oil transformer in chosen frequency bands are presented in the paper. In this case ADP, ADC, ADNC descriptors and calculated maps of these descriptors have been used. On the basis of analysis localization of sources of partial discharges in investigated oil transformer have been made.