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17 results on '"Markley, Douglas C."'

1. Performance of transducers with segmented piezoelectric stacks using materials with high electromechanical coupling coefficient

Author

Thompson, Stephen C., Meyer, Richard J., and Markley, Douglas C.

Subjects
Physics - Instrumentation and Detectors, Condensed Matter - Materials Science
Abstract

Underwater acoustic transducers often include a stack of thickness polarized piezoelectric material pieces of alternating polarity interspersed with electrodes, bonded together and electrically connected in parallel. The stack is normally much shorter than a quarter wavelength at the fundamental resonance frequency, so that the mechanical behavior of the transducer is not affected by the segmentation. When the transducer bandwidth is less than a half octave, as has conventionally been the case, stack segmentation has no significant effect on the mechanical behavior of the device. However, when a high coupling coefficient material such as PMN-PT is used to achieve a wider bandwidth, the difference between a segmented stack and a similar piezoelectric section with electrodes only at the two ends can be significant. This paper investigates the effects of stack segmentation on the performance of wideband underwater acoustic transducers, particularly tonpilz transducer elements. Included is discussion of transducer designs using single crystal piezoelectric material with high coupling coefficient compared with more traditional PZT ceramics., Comment: 26 pages including 14 figures, one table and one appendix

Published
2013
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2. Miniature multimode monolithic flextensional transducers

Author

Hladky-Hennion, Anne-Christine, Uzgur, A. Erman, Markley, Douglas C., Safari, Ahmad, Cochran, Joe K., Jr., and Newnham, Robert E.

Subjects
Finite element method -- Usage, Ultrasound imaging -- Usage, Miniature craft -- Acoustic properties, Miniature craft -- Research, Miniature objects -- Acoustic properties, Miniature objects -- Research, Business, Electronics, Electronics and electrical industries
Abstract

The symmetry and design of small, multimode flextensional transducers with active shells are studied. They combine the advantages of small size and low-cost manufacturing with control of the shape of the acoustic radiation/receive pattern.

Published
2007

7. Performance of Transducers with Segmented Piezoelectric Stacks using Materials with High Electromechanical Coupling Coefficient

Author

PENNSYLVANIA STATE UNIV STATE COLLEGE APPLIED RESEARCH LAB, Thompson, Stephen C, Meyer, Richard J, Markley, Douglas C, PENNSYLVANIA STATE UNIV STATE COLLEGE APPLIED RESEARCH LAB, Thompson, Stephen C, Meyer, Richard J, and Markley, Douglas C

Abstract

Underwater acoustic transducers often include a stack of thickness polarized piezoelectric material pieces of alternating polarity interspersed with electrodes, bonded together and electrically connected in parallel. The stack is normally much shorter than a quarter wavelength at the fundamental resonance frequency, so that the mechanical behavior of the transducer is not affected by the segmentation. When the transducer bandwidth is less than a half octave, as has conventionally been the case, stack segmentation has no significant effect on the mechanical behavior of the device. However, when a high coupling coefficient material such as PMN-PT is used to achieve a wider bandwidth, the difference between a segmented stack and a similar piezoelectric section with electrodes only at the two ends can be significant. This paper investigates the effects of stack segmentation on the performance of wideband underwater acoustic transducers, particularly tonpilz transducer elements. Included is discussion of transducer designs using single crystal piezoelectric material with high coupling coefficient compared with more traditional PZT ceramics., The original document contains color images.

Published
2012

14. Pressure Dependence of Cymbal Transducers

Author

Uzgur, Erman, primary, Markley, Douglas C., additional, Guo, Monica, additional, Snyder, Benjamin, additional, Meyer, Richard J., additional, Dogan, Aydin, additional, and Newnham, Robert E., additional

Published
2007
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17. Comparison of the properties of tonpilz transducers fabricated with <001> fiber-textured lead magnesium niobate-lead titanate ceramic and single crystals.

Author

Brosnan, Kristen H., Messing, Gary L., Markley, Douglas C., and Meyer, Richard J.

Subjects
TRANSDUCERS, FIBER-reinforced ceramics, METAL crystal growth, NIOBATES, CRYSTAL whiskers, METALS, CRYSTAL texture, PIEZOELECTRIC devices
Abstract

Tonpilz transducers are fabricated from <001> fiber-textured 0.72Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 (PMN-28PT) ceramics, obtained by the templated grain growth process, and PMN-28PT ceramic and Bridgman grown single crystals of the same composition. In-water characterization of single element transducers shows higher source levels, higher in-water coupling, and more usable bandwidth for the 81 vol % textured PMN-28PT device than for the ceramic PMN-28PT element. The 81 vol % textured PMN-28PT tonpilz element measured under large signals shows linearity in sound pressure levels up to 0.23 MV/m drive field but undergoes a phase transition due to a lowered transition temperature from the SrTiO3 template particles. Although the textured ceramic performs well in this application, it could be further improved with compositional tailoring to raise the transition temperature and better processing to improve the texture quality. With these improvements textured piezoelectric ceramics will be viable options for medical ultrasound, actuators, and sonar applications because of their ease of processing, compositional homogeneity, and potentially lower cost than single crystal. [ABSTRACT FROM AUTHOR]

Published
2009
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