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First IACMM Paper Competition

Sponsored by the
Israel Association for Computational Methods in Mechanics


Guidelines

IACMM established a paper competition for the best lecture among the papers presented at the association meetings ISCM-7 and ISCM-8. The competition was open to all current IACMM members, except for work performed in collaboration with one of the judges.

Judges 

Awards 

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. award picture

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.

Winning Paper 

SPECTRAL FINITE ELEMENTS MODEL FOR THE INVESTIGATION OF THE NON-LINEAR DYNAMICS OF COMPOSITE LAMINATED PLATE WITH PIEZOELECTRIC LAYERS

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).



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