Biography
Prof. Ji Wang
Prof. Ji Wang
Ningbo University, China
Title: A Nonlinear Formulation and Analysis of Surface Acoustic Waves in Elastic Solids with the Extended Galerkin Method
Abstract: 
The nonlinear acoustic waves in piezoelectric resonators are getting attention in product development due to the continuous shrinkage of sizes to a critical limit which causes the effect of electric field is no longer neglectable. Consequently, nonlinear formulation and analysis of wave propagation in such smaller resonators are important in the inception and development future generation of resonators with good properties.  By formulating wave propagation and vibrations with a complete set of nonlinear variables and constitutive relations, both kinematic and constitutive nonlinearities are included along with boundary conditions.  These differential equations have to be simplified with the newly proposed extended Galerkin method for a simple and efficient solution procedure.  Specifically, the weighted integration over both physical domain and the full period of time, in case of a periodic motion, is employed to both equations of motion and boundary conditions, then nonlinear variables including amplitudes and frequency, among others, appear in a set of algebraic equations as a typical nonlinear eigenvalue problem.  If it is a static problem, then it is a problem involving the solution of a system of nonlinear equations.  In principle, this is equivalent to the utilization of harmonic balance method for the approximation of trigonometric functions, as it is explained in earlier introduction of the extended Galerkin and Rayleigh-Ritz methods.  The nonlinear formulation and solution of the Rayleigh wave problem is straightforward with the extended Galerkin method, and numerical results of wave velocity versus deformation for both isotropic and anisotropic materials are obtained and also validated with the finite element analysis.  The nonlinear formulation will be applied to the analysis of surface acoustic wave resonators to address the nonlinear effect related to the development of miniaturized products with good properties as a novel technique.
Biography: 
Professor Ji Wang has been a Qianjiang Fellow Professor of Zhejiang Province at Ningbo University since 2002.  He also served as Associate Dean for Research and Graduate, School of Mechanical Engineering and Mechanics, Ningbo University, from 2013 to 2019.  Professor Ji Wang is the founding director of the Piezoelectric Device Laboratory, which is a designated Key Laboratory of City of Ningbo.  Professor Ji Wang was employed at SaRonix, Menlo Park, CA, as a senior engineer from 2001 to 2002; NetFront Communications, Sunnyvale, CA, as senior engineer and manager from 1999 to 2001; Epson Palo Alto Laboratory, Palo Alto, CA, as Senior Member of Technical Staff from 1995 to 1999.  Professor Ji Wang also held visiting positions at Chiba University, University of Nebraska-Lincoln, and Argonne National Laboratory.  He received his PhD and Master degrees from Princeton University in 1996 and 1993 and bachelor from Gansu University of Technology in 1983.  
Professor Wang has been working on acoustic waves and high frequency vibrations of elastic and piezoelectric solids for resonator design and analysis with several US and Chinese patents, over 200 journal papers, and frequent invited, keynote, and plenary presentations in major conferences around world.  He has been board members, advisors, and consultants to many leading companies in acoustic wave device industry.  Professor Wang has been a member of many international conference committees and currently serving the IEEE UFFC Technical Program Committees of the Frequency Control and Ultrasonics Symposia, the IEEE MTT-S, and the IEC TC-49.  He is also the funding chair of Committee on Mechanics of Electronic and Magnetic Devices, CSTAM, and the SPAWDA.  From 2015, Profess Wang is the editor-in-chief of Structural Longevity and members of the editorial boards of several international journals.