جستجوی مقالات مرتبط با کلیدواژه « FGPM » در نشریات گروه « مکانیک »

In the current study, the modified shear deformation theories are used for analyzing the electro-mechanical vibration of inhomogeneous piezoelectric nanoplates in conjunction with the nonlocal elasticity theory. These theories not only satisfy transverse shear traction-free conditions on the top and bottom surfaces of the plate but also consider exponential and trigonometric distributions for the transverse shear deformations. Heterogeneity of the structure is supposed to be in the thickness direction of the nanoplate and it is assumed that the simply supported functionally graded piezoelectric nanoplate is subjected to a biaxial force and an external electric voltage. The governing equations of the vibrating functionally graded piezoelectric nanoplate are obtained by using Hamilton’s principle, which are then solved by using Navier’s method to achieve the vibrational behavior of the structure. The detailed discussion is presented to explain the influences of the various parameters on the natural frequencies of functionally graded piezoelectric nanoplates. It is concluded that increasing gradient index parameter, nonlocal parameter, thickness ratio and compressive forces lead to a decrease in natural frequencies while rising tensile forces and aspect ratio increase the natural frequencies.

The mechanical behavior of a fluid-saturated functionally graded porous piezoelectric material (FGPPM) rotating disc with variable angular velocity and thickness placed in a constant magnetic field was investigated. Due to variable angular velocity, the disc was subjected to Lorentz force in two directions: radial and circumferential. It was assumed the disc is power-law functionally graded in the radial direction. The disc is uniformly porous and its thickness varies as a function of radius. First, three coupled governing partial differential equations were converted to ordinary differential equations using the separation of variable technique. Then, equations were solved using Runge-Kutta and shooting methods for the case of fixed-free boundary condition. The effect of variable angular velocity, thickness profile, inhomogeneity index, porosity and magnetic field was investigated. The results demonstrate that considering angular acceleration for the disc has a considerable effect on the Lorentz force resulted by the magnetic field. Besides, the angular velocity constant has a significant effect on the stresses and displacements in the presence of the magnetic field.

In this paper, the static response of functionally graded piezoelectric plates under mechanical, electrical, and thermal loads is studied using a meshless method. The Radial Point Interpolation Method (RPIM) is used to create the shape function to approximate field variables. Given that RPIM shape functions pass Kronecker delta condition, boundary conditions can be applied directly. The First-order Shear Deformation Plate Theory (FSDT) is used to model the behavior of the plate. Power law distribution through the thickness is considered for all of mechanical, thermal, and piezoelectric properties. Effective parameters on deflection and stresses of Functionally Graded PiezoelectricMaterial (FGPM), including different electrical and mechanical loads, thermal loads, thickness, and different boundary conditions are studied. In this paper, the effect of power law index on the deflection and stresses of the functionally graded piezoelectric plate under external loads is investigated and different results are obtained in each case of mechanical, electrical, and thermal loading. By analyzing the results of this paper, the effective structure design and sensor/actuator behavior of the plate subjected to thermal and electrical loading could be obtained.

The present study aims to investigate the analysis of stress, strain, displacement, and electrical potential of a thick hollow cylinder made of FGPM under mechanical and thermal loads. Distribution of mechanical property of material is considered along the shell stick through the power distribution function. Thermal loads have been taken to signify the difference of temperature between outer and inner surfaces for each type of mechanical property. After extracting and solving the differential equations in transient state and the observation of mechanical and thermal boundary conditions, governing functions are obtained through the following parameters: thermal conduction non-homogeneous parameters, thermal linear distribution coefficient, elastic stiffness constant, piezo-electric coefficient, and dielectric constants.

In this study, we consider the propagation of the Love-type wave in piezoelectric gradient covering layer on an elastic half-space having an imperfect interface between them. Dispersion relation has been obtained in the form of determinant for both electrically open and short cases. The effects of different material gradient coefficients of functionally graded piezoelectric material (FGPM) and imperfect boundary on the phase velocity of Love-type waves are discussed. Also, the influence of mechanically and electrically imperfect interface on the surface wave phase velocity is obtained and shown graphically. The dispersion curves are plotted and the effects of material properties of both FGPM and orthotropic material are studied. Moreover, dispersion relation of the considered microstructure depends substantially on the material gradient coefficients and width of the guiding plate. Numerical results are highlighted graphically and are validated with existing literature. The present study is the prior attempt to show the interfacial imperfection influence with the considered structure on wave phase velocity. The outcomes are widely applicable and useful for the development and characterization of Love-type mechanical waves in FGPM-layered media, SAW devices and other piezoelectric devices.

In this paper, the influence of the elastic foundation on the free vibration and buckling of thin-walled piezoelectric-based functionally graded materials (FGM) cylindrical shells under combined loadings is investigated. The equations of motion are obtained by using the principle of Hamilton and Maxwell''s equations and the Navier''s type solution used to solve these equations. Material properties are changed according to power law in the direction of thickness. In this study, the effects of Pasternak elastic foundation coefficients and also the effects of material distribution, geometrical ratios and loading conditions on the natural frequencies are studied. It is observed that by increasing Pasternak elastic medium coefficients, the natural frequencies of functionally graded piezoelectric materials (FGPM) cylindrical shell always increases. The mode shapes of FGPM cylindrical shell has been shown in this research and the results show that the distribution of the radial displacements is more significant than circumferential and longitudinal displacements.

This article presents an exact solution for an axisymmetric functionally graded piezoelectric (FGP) rotating disk with constant thickness subjected to an electric field and thermal gradient. All mechanical, thermal and piezoelectric properties except for Poisson’s ratio are taken in the form of power functions in radial direction. After solving the heat transfer equation, first a symmetric distribution of temperature is produced. The gradient of displacement in axial direction is then obtained by assuming stress equation in axial direction to be zero. The electric potential gradient is attained by charge and electric displacement equations. Substituting these terms in the equations for the dimensionless stresses in the radial and circumferential directions yield these stresses and using them in the mechanical equilibrium equation a nonhomogeneous second order differential equation is produced that by solving it, the dimensionless displacement in radial direction can be achieved. The study results for a FGP rotating hollow disk are presented graphically in the form of distributions for displacement, stresses and electrical potential.