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Open Access research with a European policy impact...

The Strathprints institutional repository is a digital archive of University of Strathclyde's Open Access research outputs. Strathprints provides access to thousands of Open Access research papers by Strathclyde researchers, including by researchers from the European Policies Research Centre (EPRC).

EPRC is a leading institute in Europe for comparative research on public policy, with a particular focus on regional development policies. Spanning 30 European countries, EPRC research programmes have a strong emphasis on applied research and knowledge exchange, including the provision of policy advice to EU institutions and national and sub-national government authorities throughout Europe.

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A new low frequency piezoelectric composite transducer

Robertson, D. and Hayward, G. and Gachagan, A. and Hyslop, J. and Murray, V. (2004) A new low frequency piezoelectric composite transducer. In: 2004 IEEE Ultrasonics Symposium, 2004-08-23 - 2004-08-27.

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Piezoelectric composite transducers have many recognised advantages for medium frequency (0.2 MHz-20 MHz) ultrasound applications. However, the extension to lower frequency bands has not been straightforward, especially with regard to active (i.e. transmission) behaviour. Manufacture from single ceramic blocks is problematic, due to polarisation limitations and inevitably, the low capacitance compromises transmit sensitivity. Alternative configurations, based on multilayered stacks can overcome most of these problems but introduce additional complexities with device manufacture and operational robustness. This paper presents a different method for manufacture of low frequency composites, utilising the fundamental symmetric Lamb mode (S0) in a conventional thickness drive piezoelectric plate. A composite plate, with electrodes positioned on the major faces, is driven at the fundamental frequency corresponding to the plate length dimension. This is shown to correspond with the S0 mode and demonstrates low loss, longitudinal wave propagation, with uniform surface displacement at the end faces that are normal to the direction of wave travel. A combination of experiment and finite element modelling using PZFlex is used to demonstrate the validity of this approach for low frequency (10 kHz-100kHz) 2-2 piezoelectric composite arrays. Measured coupling coefficients of approximately 0.5 for pzt5h ceramic and 0.8 for single crystal pmn-pt are shown to provide good agreement with theory as do laser scans of the radiating surface profile. The simulated TVR is superior to ceramic based tonpilz configurations of a similar frequency