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| The winner is Ishai Rinat of the Department of Mechanical Engineering, Technion - Israel Institute of Technology. The award-winning presentation was given at the Seventh Israel Symposium on Computational Mechanics (ISCM-7) on 14 April, 1999, at the Ben-Gurion University of the Negev, Beer-Sheva, Israel. Mr. Rinat presented his paper at the European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2000), with IACMM support for expenses in attending the meeting. In addition to the award, Mr. Rinat received a certificate from IACMM at the Ninth Israel Symposium on Computational Mechanics (ISCM-9) on Thursday, 26 October, 2000 at the Technion in Haifa. |
 Professor Pinhas Bar-Yoseph (left), president of IACMM, presenting the certificate to Mr. Ishai Rinat, the award winner, at the Ninth Israel Symposium on Computational Mechanics. |
Second prize goes to Tanya Matskewich of the School of Computer Science and Engineering, The Hebrew University of Jerusalem. Ms. Matskewich received complimentary IACMM membership for three years and a certificate from IACMM.
Y. Rinat* and P. Bar-Yoseph
Department of Mechanical Engineering
Technion - Israel Institute of Technology, Haifa, Israel.
e-mail: merbygr@cmlp.technion.ac.il
ABSTRACT
It is very natural to incorporate the piezoelectric effect into a flexible
structure and create a "smart" structure. However, very little work which
takes into account the nonlinear deformation has been done. This research
work tries to fulfill this gap by offering a relative simple theory, but
yet accurate enough, which solves the nonlinear dynamic response of thin
composite laminated plates with piezoelectric layers.
The approximate nonlinear Euler-Lagrange governing equations of motion
and the associated boundary conditions were derived from Hamilton
principle which was modified to include the piezoelectric effect [1]. The
Reissner-Mindlin (FSDT) thin plate theory was used for the assumed
equivalent single-layer displacement field, whereas the potential
function for the piezoelectric laminas was modeled using a layerwise
discretization theory in the thickness direction. The nonlinearity is due
to the assumption that the structure undergoes large rotations (small
strains), hence, the strains were taken in the Von-Karman sense. High
order spectral elements were chosen for the implicit FEM model. For
purposes of accuracy and stability, the initial conditions were fulfilled
in an average or weak form [2], [3]. The proposed novel model is a good
compromise between simplicity, accuracy and computational efficiency.
An analysis of an anti-symmetric simply supported square piezoelectric
plate loaded electrically and mechanically was carried out. It was shown
that the linear model, unlike the new nonlinear one, was non satisfactory
in predicting global responses and local effects. Significant
differences, between the two theories were observed in both the
elastostatic and the elastodynamic cases. The piezoelectric effect was
shown to have a significant influence on the plate's shape and stresses,
and that it can serve as an efficient mean to control the plate. The
results emphasize the different nature of the electrical load compared to
the mechanical one. A parameter study was also carried out. Finally, the
scheme convergence and stable characteristics were shown.
REFERENCES
[1] H. F. Tiersten, Linear Piezoelectric Plate Vibrations, Plenum,
New-York, (1969).
[2] D. Fisher, Spectral Element Methods for Nonlinear Dynamical Systems,
M.Sc. thesis, Mechanical Engineering, Technion - Israel Institute of
Technology, Haifa, (1996).
[3] D. Aharoni and P. Bar-Yoseph, "Mixed Finite Element Formulations in
the Time Domain for Solution of Dynamic Problems", Computational
Mechanics, Vol. 9, pp. 359-374, (1992).
