Modelling of ultrasonic transduction and measurement using finite elements

Forsyth, SA, 2000. Modelling of ultrasonic transduction and measurement using finite elements. PhD, Nottingham Trent University.

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Abstract

The aim of this research was to investigate the behaviour of resonant transducers used for the detection of ultrasound, specifically acoustic emission (AE) in nondestructive evaluation (NDE) of materials. PAFEC-FE Vibroacoustics finite element (FE) software was employed on a computer workstation in order to gain an insight into the best methods of modelling ultrasonic transducers.

Two main methods of modelling were used. The first was a sinusoidal analysis, used to predict transducer frequency response and vibrational behaviour. The second was a transient analysis, in which the transducer response to a simulated AE event was predicted. Within these two broad categories, further variations upon the methods were investigated and evaluated.

Acoustic FE modelling was shown to provide the most realistic results for the sinusoidal analyses. Close agreement between FE predictions and experimental measurements were achieved for two different transducer designs. The software was then used to investigate transducer performance changes due to geometry and mounting conditions. It was also used to optimise the performance of a metal-ceramic composite design. Agreement with theory was also shown where appropriate.

Two methods of modelling an AE event were utilised in order to predict the response of a resonant transducer to a propagating wave in a plate. Both methods showed agreement and open up the possibility for modelling the transducer response to a variety of input sources. Similarities with experimental data showed that future work promises to be extremely useful in understanding the AE source and transducer response relationship. Improved agreement would stem from comparable bandpass filtering.

Resonant transducers appear to be capable of representing the deformation at the transducer surface before going into their resonant mode of vibration. Lamb wave modes which propagate in a plate are shown to influence the shape of the waveform, leading to information about the type and location of the source.

Further work to improve the realism of the modelling, associated with increased computing power, will allow the NDE engineer to obtain a much greater understanding of what the transducers are detecting. The transducer designer will also be able to tailor make transducers for specific applications with improved performance.

Item Type:	Thesis
Creators:	Forsyth, S.A.
Date:	2000
ISBN:	9781369316544
Identifiers:	Number Type PQ10183453 Other
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	30 Sep 2020 10:02
Last Modified:	12 Sep 2023 14:07
URI:	https://irep.ntu.ac.uk/id/eprint/41008

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