Location

Ithaca, NY

Start Date

1978 12:00 AM

Description

Piezoelectric transducers, long used in the generation and detection of ultrasonic waves, have more recently been the detector of choice for acoustic emission signals. Optical probing methods, however, have several important advantages for acoustic emission studies: (1) they have an inherent broad frequency response, free from mechanical resonances, (2) they do not interfere with the acoustic waves. (3) since the focused optical beam diameters are typically only a few hundredths of a millimeter, optical methods can probe very close to a crack or a twin, (4) they can probe internally in transparent media, and (5) they can be used over a very wide temperature range. In this paper we compare the response of an optical probe with that of a commercial acoustic emission transducer. Since the optical probe permits absolute calibration, we can not only measure acoustic emission amplitudes, but also determine the quantitative response of the piezoelectric transducer to known acoustic disturbances of various kinds over a range of frequencies. We include measurements of real acoustic emission from twinning in two metals and stress corrosion cracking in steel.

Book Title

Proceedings of the ARPA/AFML Review of Progress in Quantitative NDE

Chapter

5. New Techniques and Phenomena

Pages

161-165

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Optical Detection of Acoustic Emission Signals

Ithaca, NY

Piezoelectric transducers, long used in the generation and detection of ultrasonic waves, have more recently been the detector of choice for acoustic emission signals. Optical probing methods, however, have several important advantages for acoustic emission studies: (1) they have an inherent broad frequency response, free from mechanical resonances, (2) they do not interfere with the acoustic waves. (3) since the focused optical beam diameters are typically only a few hundredths of a millimeter, optical methods can probe very close to a crack or a twin, (4) they can probe internally in transparent media, and (5) they can be used over a very wide temperature range. In this paper we compare the response of an optical probe with that of a commercial acoustic emission transducer. Since the optical probe permits absolute calibration, we can not only measure acoustic emission amplitudes, but also determine the quantitative response of the piezoelectric transducer to known acoustic disturbances of various kinds over a range of frequencies. We include measurements of real acoustic emission from twinning in two metals and stress corrosion cracking in steel.