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Proceedings Paper

Finite element analysis of hysteresis effects in piezoelectric transducers
Author(s): Reinhard Simkovics; Hermann Landes; Manfred Kaltenbacher; Johann Hoffelner; Reinhard Lerch
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Paper Abstract

The design of ultrasonic transducers for high power applications, e.g. in medical therapy or production engineering, asks for effective computer aided design tools to analyze the occurring nonlinear effects. In this paper the finite-element-boundary-element package CAPA is presented that allows to model different types of electromechanical sensors and actuators. These transducers are based on various physical coupling effects, such as piezoelectricity or magneto- mechanical interactions. Their computer modeling requires the numerical solution of a multifield problem, such as coupled electric-mechanical fields or magnetic-mechanical fields as well as coupled mechanical-acoustic fields. With the reported software environment we are able to compute the dynamic behavior of electromechanical sensors and actuators by taking into account geometric nonlinearities, nonlinear wave propagation and ferroelectric as well as magnetic material nonlinearities. After a short introduction to the basic theory of the numerical calculation schemes, two practical examples will demonstrate the applicability of the numerical simulation tool. As a first example an ultrasonic thickness mode transducer consisting of a piezoceramic material used for high power ultrasound production is examined. Due to ferroelectric hysteresis, higher order harmonics can be detected in the actuators input current. Also in case of electrical and mechanical prestressing a resonance frequency shift occurs, caused by ferroelectric hysteresis and nonlinear dependencies of the material coefficients on electric field and mechanical stresses. As a second example, a power ultrasound transducer used in HIFU-therapy (high intensity focused ultrasound) is presented. Due to the compressibility and losses in the propagating fluid a nonlinear shock wave generation can be observed. For both examples a good agreement between numerical simulation and experimental data has been achieved.

Paper Details

Date Published: 19 June 2000
PDF: 12 pages
Proc. SPIE 3984, Smart Structures and Materials 2000: Mathematics and Control in Smart Structures, (19 June 2000); doi: 10.1117/12.388777
Show Author Affiliations
Reinhard Simkovics, Univ. of Erlangen-Nuremburg (Germany)
Hermann Landes, Univ. of Erlangen-Nuremburg (Germany)
Manfred Kaltenbacher, Univ. of Erlangen-Nuremburg (Germany)
Johann Hoffelner, Univ. of Linz (Austria)
Reinhard Lerch, Univ. of Erlangen-Nuremburg (Germany)

Published in SPIE Proceedings Vol. 3984:
Smart Structures and Materials 2000: Mathematics and Control in Smart Structures
Vasundara V. Varadan, Editor(s)

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