and acoustic wave resonators and sensors

报告人：Professor Jiashi Yang
Department of Mechanical and Materials Engineering, University of

Nebraska-Lincoln, USA
时  间：2013年5月21日下午4:00-5:30 
地  点：力学系三楼会议室（南一楼东北角E320） 
邀请人：胡元太教授

Professor Jiashi Yang：美国Nebraska大学教授，1993年获得Princeton大学博士

学位。一直从事压电理论和压电声波器件研究，受到美国陆军部资助。他自2004年起

一直担任IEEE Transactions on Ultrasoncis, Ferroelectrics, and Frequency

Control编委(Associate Editor)，已发表论文270余篇，出版专著4本，获美国专利

4项，是压电结构理论和压电器件分析方面的国际权威专家。

Abstract: 
Piezoelectric crystals have been widely used to make acoustic wave

resonators as frequency standards for time-keeping and frequency

operations in electronic equipment. Many acoustic wave resonators are

based on thickness-shear modes in crystal plates. Exact analysis of

thickness-shear vibrations of crystal plates using the theory of

anisotropic elasticity or piezoelectricity are complicated and can only

produce limited theoretical results useful in the design of crystal

resonators. Beginning in the 1950s, R.D. Mindlin and his students

developed two-dimensional equations for vibrations of piezoelectric

plates. Mindlin’s equations are mainly for the fundamental thickness-

shear mode. For overtone thickness-shear modes, in the 1970s and 1980s,

H.F. Tiersten and his coworkers derived approximate two-dimensional

scalar differential equations for piezoelectric plates. These two-

dimensional equations have been widely used in the analysis of plate

acoustic wave resonators. 
Relatively more recently, the applications of acoustic wave resonators

for sensing applications are rapidly growing. In these applications,

plate crystal resonators are under various surface loads including mass

layers, liquids and gases, etc. Conventional equations for crystal

plates are not directly useful for these applications. We generalize

existing plate equations to include surface loads through surface

acoustic impedance in a general manner. The equations obtained can be

conveniently used for the study of acoustic wave sensors. A few

problems are analyzed as examples.

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