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TOFEL, P. ŠIKULA, J. HÁJEK, K. TROJANOVÁ, Z. BUMBÁLEK, L.
Originální název
Cracks detection in Mg alloy by electro-ultrasonic spectroscopy
Typ
článek v časopise - ostatní, Jost
Jazyk
angličtina
Originální abstrakt
New non-destructive testing (NDT) method is based on the effect of the ultrasonic vibrations on the electron transport in samples with macroscopic defects as cracks or defect centers affecting electrical conductivity. On the frequency given by the subtraction of exciting frequencies new intermodulation signal appears. Its value is given by electric resistance modulation by the defects and un-homogeneities in the sample structure. In our experiment we used the ultrasonic actuator with frequency fU when the period of wave is longer than the dielectric relaxation time in analyzed sample. In this case the effects of electron bunching by ultrasonic wave are negligible. The ultrasonic wave length is much larger than the electrons mean free path and the wave period is much longer than the mean free time among the electrons collision with scattering centers and defects. Then the electron transport is described by the quasi-steady state transport equation in one-electron approximation. Because of the requirement of charge neutrality, no net AC electric current with the ultrasonic wave frequency fU can be carried by the wave. Similar situation exists for samples excited by standing ultrasonic waves. The electrical conductivity varies with time due to that the cracks geometry is changed with frequency of the ultrasonic vibration. The sample conductivity is affected mainly by the presence of cracks and defects boundaries perpendicular to the electric current density vector. In our experiment the amplitude of ultrasonic vibration is so low that no new cracks are generated and then the proposed testing method belongs to NDT.
Klíčová slova
NDT, spectroscopy, resistance change, crack geometry change
Autoři
TOFEL, P.; ŠIKULA, J.; HÁJEK, K.; TROJANOVÁ, Z.; BUMBÁLEK, L.
Rok RIV
2011
Vydáno
18. 1. 2011
Nakladatel
Trans Tech Publications
Místo
Switzerland
ISSN
1013-9826
Periodikum
Key Engineering Materials (print)
Ročník
465
Číslo
1
Stát
Švýcarská konfederace
Strany od
350
Strany do
353
Strany počet
4
BibTex
@article{BUT50237, author="Pavel {Tofel} and Josef {Šikula} and Karel {Hájek} and Zuzanka {Trojanová} and Leoš {Bumbálek}", title="Cracks detection in Mg alloy by electro-ultrasonic spectroscopy", journal="Key Engineering Materials (print)", year="2011", volume="465", number="1", pages="350--353", issn="1013-9826" }