Waveforms and Frequency Spectra of Acoustic Emissions

Stephens, R.W.B.; Pollock, Adrian A.

doi:10.1121/1.1912715

Cited by 57 publications

(19 citation statements)

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“…Viewed in the frequency domain, information is transmitted independently, frequency by frequency, so that filtering and other digital signal techniques can be employed to separate useful signals from noise. The virtues of using a frequency method for source characterization have also been discussed by Stephens and Pollock [13] and by Tatro [14].…”

Section: The Transfer Function Formalism 77mentioning

confidence: 99%

Acoustic Emission: Establishing the Fundamentals

Eitzen¹,

Wadley²

1984

J. RES. NATL. BUR. STAN.

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In the mid-1970's a program of fundamental research was initiated at NBS to improve the scientific understanding of acoustic emission. Many individual results of this research have been reported in the literature and are beginning to be incorporated in a new generation of acoustic emission instrumentation, in improved test methodologies, and in the analysis of data. Here, we summarize the problems faced by acoustic emission <{llidway through the last decade, review the accomplishments of the NBS program and related research programs, and outline the research that will be required in future years.

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Section: The Transfer Function Formalism 77mentioning

confidence: 99%

Acoustic Emission: Establishing the Fundamentals

Eitzen¹,

Wadley²

1984

J. RES. NATL. BUR. STAN.

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“…Stephens and Pollock [15] argued that an oscillatory or double pulse model has a mean value of zero and leads to no change in the static stress level. However, AE are produced during irreversible changes in the material.…”

Section: Ae Sources In Precision Turningmentioning

confidence: 99%

“…During propagation, these waves suffer multiple reflections, mode conversions and attenuation. AE waves will also excite the resonances in small specimens [15], due to the broadband nature of the single pulse stress source. Therefore, a model for the transmission path seems to be necessary in order to equalise the distorted stress waves arriving to the sensor location.…”

Section: Transmission Path and Measurement Systemmentioning

confidence: 99%

“…Mechanisms by which AE are produced by dislocations and those which are related to friction are fundamentally different. Nevertheless, stress waves produced by both, a single moving dislocation and those resulting from friction, have been modelled as very short lifetime stress pulses [12,15,16]. These short life pulses are believed to be uncorrelated [17] and their probability density function (PDF) is unknown [18].…”

Section: Ae Sources In Precision Turningmentioning

confidence: 99%

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Bicepstrum based blind identification of the acoustic emission (AE) signal in precision turning

Iturrospe

Dornfeld

Atxa

et al. 2005

Mechanical Systems and Signal Processing

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It is believed that the acoustic emissions (AE) signal contains potentially valuable information for monitoring precision cutting processes, as well as to be employed as a control feedback signal. However, AE stress waves produced in the cutting zone are distorted by the transmission path and the measurement systems. In this article, a bicepstrum based blind system identification technique is proposed as a valid tool for estimating both, transmission path and sensor impulse response. Assumptions under which application of bicepstrum is valid are discussed and diamond turning experiments are presented, which demonstrate the feasibility of employing bicepstrum for AE blind identification. r

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“…An Acoustic Emission (AE) signal is a fast sequence of low amplitude, high bandwidth bursts in the range of approximately 100 kHz to some MHz [4]. AE has to be separated from the low frequency signals below 50 kHz, which are the results of mechanical noise and machine vibrations, because they do not deliver information about the structural health or overload conditions.…”

Section: Introductionmentioning

confidence: 99%