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1

An equivalent single layer shear deformation plate theory with superposed shape functions for laminated composite plates

Aydogdu M.

Archives of Mechanics

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2019

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Vol. 71, nr 3

239--262

EN

A single layer shear deformation plate theory with superposed shape functions for laminated composite plates has been proposed. Some of the previously developed, five degrees of freedom shear deformation theories, including parabolic [1], hyperbolic [2], exponential [3] and trigonometric [4] plate theories have been superposed by applying different theories in the different in- plane directions of the composite plate. Statics and dynamics of composite plate problems have been investigated. It was obtained that using different shape functions in the different in-plane directions may decrease the percentage error of stress and deflection. Present hyperbolic-exponential and parabolic-exponential theories predict stiffer properties (give lower bending and stress values, and higher frequency, and buckling loads when compared to the 3-D elasticity). Some improvements were determined for y-z component of the transverse shear stress using hyperbolic-exponential and parabolic-exponential theories for symmetric cross-ply composite plates when compared to available single shape function plate models. Global behaviours (vibration frequency and critical buckling loads) are predicted within %5 accuracy similar to plate theories with single shape functions.

2

Wave propagation characteristics in functionally graded double-beams

Karacam F., Aydogdu M.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 3

143--149

EN

The wave propagation characteristics of functionally graded (FG) double-beams are investigated by use of Euler-Bernoulli beam theory. Two beams are connected by a Winkler foundation. The wave propagation characteristics like frequency, phase and group velocities are obtained for different wave numbers and material properties. Four frequencies are obtained for functionally graded double-beam system. It is obtained that flexural and axial waves are coupled for FG double-beams.

3

Analysis of free torsional vibration in carbon nanotubes embedded in a viscoelastic medium

Arda M, Aydogdu M.

Advances in Science and Technology. Research Journal

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2015

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Vol. 9, nr 26

28--33

EN

Carbon Nanotubes (CNTs) have a great potential in many areas like electromechanical systems, medical application, pharmaceutical industry etc. The surrounding physical environment of CNT is very important on torsional vibration behavior of CNT. Damp¬ing and elastic effect of medium to the torsional vibration of CNTs are investigated in the present study. Governing equation of motion of nanotube is obtained using Eringen’s Nonlocal Elasticty Theory. The effects of some parameters like nonlocal parameter, stiffness parameter and nanotube length are studied in detail.

4

The effect of the electron sound speed on wave propagation in the ionospheric plasma

Yesil A., Aydogdu M.

Acta Geophysica

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2011

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Vol. 59, no. 2

398-406

EN

In this study, the effect of the electron sound speed on the extraordinary wave propagation is calculated without an approximation for either collisional or collisionless cases in the ionospheric plasma by using the real geometry of the Earth’s magnetic field for the Northern Hemisphere. It is observed that there is no remarkable effect on the propagation of the extraordinary wave, especially at reflection altitudes. But it is also observed that the magnitudes of k2 (the square of the wave number) have changed every season, and the phase velocity of wave in warm ionospheric plasma has increased.