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Mechanics is hard to explain because many people do not realize the underline principles of today's cars, aircrafts, bridges, buildings, and so on are from Mechanics with its variations like Solid Mechanics for solid structures by steel, lumber, and concrete, and Fluid Mechanics for fluid-structure interactions, and other branches.  Mechanics have been practiced by engineers in all fields through design manuals, tables, and software so usually they do not deal with the complicated differential equations and solutions.  The history of mechanics has been very long and many great mathematicians have contributed to it through derive and solve many equations related to the familiar subject like plates, beams, and other elements.

One great advancement of mechanics in last century is the sophistication of the finite element method for many practical engineering problems.  Actually, most products we see and use today are designed based on the analysis of finite element method.  The method has quickly evolved to a general method for differential equations in many disciplines.

I have been working on building structures, nuclear reactor structures, and others with the finite element method and some general purpose software package like ANSYS.  But lately, I have been concentrating on the analysis of piezoelectric structures, which require special attention due to its coupling of mechanical fields and electric fields and high frequency.  Since there is no commercial codes for the problem, I developed a special software with Professor Yook-Kong Yong for the high frequency vibration analysis of quartz crystal resonators.  The program has been successfully utilized by design engineers to identify the coupling of vibration modes, find the best design parameters, and calculate the electrical output.  The program is based on a special plate theory for crystal resonators.

For electronic components and devices, mechanics are also being employed to solve problems related to packaging and design, because most of time the device performance will be changed due to the mechanical effects related to packaging and installation.  As a results, special branches of mechanics have been created lately for semiconductor and optical industries.  Usually in these applications the mechanical effects have to be considered along with electrical and thermal effects.  All these combinations made the precise analysis very difficult to carry out, but it has been proven that the experimental work will compensate the analytical results to make good products. 

Also lately the MEMS research and production also add new topics to mechanics research.  As usual, the interaction of electrical, optical, and mechanical fields are considered.  For most applications, it will be clear that special software has to be developed on the top of the commercial software for better analysis.

PUBLICATIONS 

Journals 

1. Ji Wang: Vibration of stepped beams on elastic foundations, Journal of Sound and Vibration, 149(2), 1990. 
2. Ji Wang: Free vibration of stepped circular plates on elastic foundations, Journal of Sound and Vibration, 159(1), 1992. 
3. P. C. Y. Lee and Ji Wang: Vibrations of AT-cut quartz strips of narrow rectangular cross-section and finite length, Journal of Applied Physics, 75(12), pp. 7681-7695, 1994. 
4. Ji Wang, P. C. Y. Lee, and D. H. Bailey: Thickness-shear and flexural vibrations of linearly contoured crystal plates, Computer & Structures, 70(4), pp. 437-445, 1999. 
5. Ji Wang: Generalized power series solutions of classical circular plates with variable thickness, Journal of Sound and Vibration, 202(4):593-599, 1997. 
6. Ji Wang: Comments on A direct solution for the transverse vibration of Euler-Bernoulli wedge and cone beams, Journal of Sound and Vibration, 185(1), pp. 190-191, 1995. 
7. P. C. Y. Lee and Ji Wang: Thickness-shear and flexural vibrations of contoured crystal strip resonators, Journal of Applied Physics, 79(7), pp. 3403-3410, 1996. 
8. P. C. Y. Lee and Ji Wang: Piezoelectrically forced thickness-shear and flexural vibrations of contoured strip resonators of quartz, Journal of Applied Physics, 79(7), pp. 3411-3422, 1996. 9. P. C. Y. Lee and Ji Wang: Frequency-temperature relations of thickness-shear and flexural vibrations of contoured quartz resonators, Journal of Applied Physics, 80(6), pp. 3457-3465, 1996. 
10.Ji Wang and E. Momosaki: The piezoelectrically forced vibrations of AT-cut quartz strip resonators, J. Applied Physics, 81(4), pp. 1868-76, 1997. 
11.Ji Wang, Y.-K. Yong, and T. Imai: Finite element analysis of the piezoelectric vibrations of quartz plate resonators with higher-order plate theory, Intl. J. Solids Struct., 36(15), pp. 2303-2319, 1999. 
12.Y.-K. Yong, Ji Wang, and T. Imai: On the accuracy of Mindlin plate predictions for the frequency-temperature behavior of resonant modes in AT- and SC-cut quartz plates, IEEE Trans. Ultrason., Ferroelect, and Freq. Contr., 46(1), pp. 1-13, 1999. 
13. Ji Wang, J-D Yu, Y-K Yong, and T. Imai: A new theory for electroded piezoelectric plates and its finite element application for the forced vibrations of quartz crystal resonators, Intl. J. Solids Struct., 37, pp. 5653-5673, 2000.
14. Ji Wang and J. S. Yang: Higher-order theories of piezoelectric plates and applications, Applied Mechanics Review, 53(4), pp. 87-99, 2000.

Conferences