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Studies of ultrasound fields generated by non-uniformly loaded piezoelectric discs
2009 (English)Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

Piezoelectric discs are commonly used when generating ultrasonic waves for measurement and investigation purposes. The electronics needed for a complete ultrasonic measurement system can be realized as an integrated circuit. For several reasons, it is advantageous to mount the circuitry physically as close to the piezoelectric disc as possible, thus creating a small and compact unit. One solution is to mount the chip containing the electronics directly on the back-side of the disc. This will however present a non-uniform mechanical load at the rear side of the disc. The purpose of this master's thesis is to investigate the influence of a mechanical load on the radiated sound field generated by the piezoelectric disc. In the presented study, a laboratory setup was designed and built to perform an experimental study on the effect of the radiated field from different mechanical loadings of the disc. Piezoelectric discs of Pz27 material were used in generating an ultrasonic field. The discs were mounted in an elastic frame to provide a setup that, as close as possible, will allow the disc to move freely in the axial direction. The disc and holder were immersed in a temperature controlled water tank. The ultrasonic field was measured using a ultrasonic hydrophone and a 3-D scanning system. The data collection, scanning and processing of the collected data was performed using MatlabTM. Comparisons are presented between unloaded and loaded discs in the far field. A study of loaded discs in the near field is also presented. A comparison shows that the prescence of the load on the disc does not significantly affect the 2-D shape of the radial energy density. However, the resonant frequency of the disc is shifted and an increase of the transmitted acoustic energy is found in the recorded signal. In the near field, an effect from the wraparound connection is distinguished. All measurements are commented and presented. Recommendations for further investigations are given.

Place, publisher, year, edition, pages
Keyword [en]
Technology, ultrasound, intensity, mapping, non-uniform, mechanical load
Keyword [sv]
URN: urn:nbn:se:ltu:diva-43403ISRN: LTU-PB-EX--09/007--SELocal ID: 149d5d80-25cf-4055-bf80-75c1e286cf9dOAI: diva2:1016635
Subject / course
Student thesis, at least 15 credits
Educational program
Electrical Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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