Design of a self-calibrating simulated acoustic emission source

• Published in: Ultrasonics 2000, Vol.37 (8), p.589-594
• Main Authors: Evans, M.J., Webster, J.R., Cawley, P.
• Format: Article
• Language: English
• Subjects: Acoustic emission; Acoustical measurements and instrumentation; Acoustics; Calibration; Conical transducers; Cross-disciplinary physics: materials science; rheology; Equipment Design; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Materials science; Materials testing; Nondestructive testing: ultrasonic testing, photoacoustic testing; Physics; Point acoustic sources; Self-calibration; Transduction; acoustical devices for the generation and reproduction of sound; Ultrasonics; Ultrasonography - instrumentation
• ISSN: 0041-624X; 1874-9968
• DOI: 10.1016/S0041-624X(99)00110-9

The use of conical piezoelectric transducers as point acoustic sources has been investigated. It has been shown that transducers based on a design originally developed at the National Institute for Standards and Technology in the USA can be used as point transmitters over the frequency range of interest in acoustic emission measurements (100 kHz to around 1 MHz). They should, therefore, be suitable for use in experiments to calibrate structures so that acoustic emission source strengths can be determined. It has also been shown that measurements of the response of the transmitting transducer backing can be used to assess the coupling efficiency, and hence to remove concerns about inconsistent coupling affecting the calibration measurements. The results indicate that the variation of the backing response with coupling is due to a shift in the resonance frequencies of the transducer with the mechanical load impedance. If other transducers can be shown to behave in a similar fashion this effect could be used to measure coupling in standard acoustic emission and ultrasonic transducers.