Location

Ithaca, NY

Start Date

1978 12:00 AM

Description

Acoustic Emission (AE) signals are notorious for their complexity and irreproducibility. Because AE source characteristics are virtually unknown and because the detected AE signals are colored by the propagation media, the sensor response and the instrumentation set tings, interpretations of test results such as spectral analysis or correlation studies are mostly qualitative and sometimes controversial; theories either are empirically derived or cannot be verified by experiments . In this paper, we sketch an approach to the AE signal analysis problem. We first report the development of a theory which allows the computation of the displacement as a function of time at an arbitrary ·point on an infinite plate due to an arbitrary point source force function . The theory is based on a new Fourier inversion technique which yields exact formulas similar to those developed for seismological "ray" theories. We then report experimental results obtained on a 2. 52 em thick aluminum plate using a reproducible step function stress release pulse as a simulated AE signal and a wide band displacement capacitive transducer as a sensor. The measurements are in quantitative agreement with the predictions of theory. We also discuss applications wherein the simulated signal, capacitive transducer and plate theory are used for AE source signature analysis, and sensor calibration problems.

Book Title

Approach to Acoustic Emission Signal Analysis - Theory and Experiment

Chapter

5. New Techniques and Phenomena

Pages

166-169

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Approach to Acoustic Emission Signal Analysis - Theory and Experiment

Ithaca, NY

Acoustic Emission (AE) signals are notorious for their complexity and irreproducibility. Because AE source characteristics are virtually unknown and because the detected AE signals are colored by the propagation media, the sensor response and the instrumentation set tings, interpretations of test results such as spectral analysis or correlation studies are mostly qualitative and sometimes controversial; theories either are empirically derived or cannot be verified by experiments . In this paper, we sketch an approach to the AE signal analysis problem. We first report the development of a theory which allows the computation of the displacement as a function of time at an arbitrary ·point on an infinite plate due to an arbitrary point source force function . The theory is based on a new Fourier inversion technique which yields exact formulas similar to those developed for seismological "ray" theories. We then report experimental results obtained on a 2. 52 em thick aluminum plate using a reproducible step function stress release pulse as a simulated AE signal and a wide band displacement capacitive transducer as a sensor. The measurements are in quantitative agreement with the predictions of theory. We also discuss applications wherein the simulated signal, capacitive transducer and plate theory are used for AE source signature analysis, and sensor calibration problems.