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Descripción
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| The shear mode and other natural modes of resonance of the standard, in-plane polarized, piezoceramic plate, are coupled [1]. To overcome this problems, a thickness polarized shear plate, excited in length [2], was consider for determination of shear properties by the automatic iterative analysis of the complex impedance spectra at resonance [3]. Both easier ceramic polarization and easy decoupling of the fundamental shear mode and other undesired natural resonance modes of the plate were accomplished by fine tunning of the thickness of the sample. In this work, a plate of Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramic was studied. Its initial thickness for polarization was t=1.09 mm, and lateral dimensions were L=8.18 mm and w (distance between electrodes for electrical excitation of the resonance)=6.20 mm. Thickness was reduced in steps of 0.01 mm to a final value of t=0.5mm. An study of the periodic evolution of the material coefficients as the coupling of modes evolves with the change in the aspect ratio (w/t) of the plate is here presented. A number of uncoupled shear resonances of the plate, amenable for material characterization, can be obtained in the range of aspect ratios between 5.5 and 12.5. Noticeably, the standard measurement methods requires values higher than 20 to minimize, though not eliminate, the effect of the undesired modes. The automatic iterative method was modified by expert selection of the required frequencies at the resonance for monitoring the material properties when coupling of modes takes place. On the one hand, the results show that the precise determination of the characteristic frequencies of an electromechanical resonance is not enough to obtain precise and accurate properties of piezoceramics, including all losses (piezoelectric, elastic and dielectric), from complex impedance measurements [4]. Besides, precise values of the complex impedance around resonance and antiresonance frequencies are also required to properly determine the material losses. On the other hand, the obtained results shed light for the understanding of the coupling phenomena in thickness poled shear plates. | |
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Internacional
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No |
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Nombre congreso
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XIV REUNIÓN NACIONAL DE ELECTROCERÁMICA |
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Tipo de participación
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960 |
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Lugar del congreso
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Castellón |
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Revisores
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Si |
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ISBN o ISSN
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DOI
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Fecha inicio congreso
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26/06/2019 |
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Fecha fin congreso
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28/06/2019 |
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