Location

Snowmass Village, CO

Start Date

1-1-1995 12:00 AM

Description

Previous work has compared the relative performance of various wide-band ultrasonic transducers used as receivers [1]. Studies have also been made comparing the merits of various optical sensors [2] and evaluating their applicability to acoustic emission (AE) [3]. In this paper, the calculated and measured sensitivities of such transducers are compared with the sensitivity of transducers capable of detecting low amplitude AE events in steels [4, 5]. While optical sensors appear to provide many practical advantages over contact sensors, particularly at very low frequencies, it is found that they cannot meet the sensitivity requirements for wide-band AE detection in metals. Furthermore, it is found that a new transducer, recently developed at NIST, has sufficient sensitivity for such applications. In particular, this high-fidelity, high-sensitivity (HFHS) sensor is found to exhibit sensitivity which approaches the “thermal rattle” limit in aluminum within 10 dB over the 250 kHz to 1 MHz region. Also, it is shown that the new transducer’s noise floor is well below both the necessary sensitivity level to monitor AE in metals and the sensitivity limits of both optical and airborne-sound transducers. Furthermore, its performance is in good agreement with the computer model used in its design.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

14A

Chapter

Chapter 4: Transducers, Sensors, and Process Control

Section

Ultrasonic Transducers

Pages

967-974

DOI

10.1007/978-1-4615-1987-4_122

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Absolute Sensitivity of Air, Light and Direct-Coupled Wideband Acoustic Emission Transducers

Snowmass Village, CO

Previous work has compared the relative performance of various wide-band ultrasonic transducers used as receivers [1]. Studies have also been made comparing the merits of various optical sensors [2] and evaluating their applicability to acoustic emission (AE) [3]. In this paper, the calculated and measured sensitivities of such transducers are compared with the sensitivity of transducers capable of detecting low amplitude AE events in steels [4, 5]. While optical sensors appear to provide many practical advantages over contact sensors, particularly at very low frequencies, it is found that they cannot meet the sensitivity requirements for wide-band AE detection in metals. Furthermore, it is found that a new transducer, recently developed at NIST, has sufficient sensitivity for such applications. In particular, this high-fidelity, high-sensitivity (HFHS) sensor is found to exhibit sensitivity which approaches the “thermal rattle” limit in aluminum within 10 dB over the 250 kHz to 1 MHz region. Also, it is shown that the new transducer’s noise floor is well below both the necessary sensitivity level to monitor AE in metals and the sensitivity limits of both optical and airborne-sound transducers. Furthermore, its performance is in good agreement with the computer model used in its design.