Electro-magneto-thermo-mechanical Behaviors of a Radially Polarized FGPM Thick Hollow Sphere

ABSTRACT In this study an analytical method is developed to obtain the response of electro-magneto-thermoelastic stress and perturbation of a magnetic field vector for a thick-walled spherical functionally graded piezoelectric material (FGPM). The hollow sphere, which is placed in a uniform magnetic field, is subjected to a temperature gradient, inner and outer pressures and a constant electric potential difference between its inner and outer surfaces. The thermal, piezoelectric and mechanical properties except the Poisson's ratio are assumed to vary with the power law functions through the thickness of the hollow sphere. By solving the heat transfer equation, in the first step, a symmetric distribution of temperature is obtained. Using the infinitesimal electro-magnetothermo-elasticity theory, then, the Navier's equation is solved and exact solutions for stresses, electric displacement, electric potential and perturbation of magnetic field vector in the FGPM hollow sphere are obtained. Moreover, the effects of magnetic field vector, electric potential and material in-homogeneity on the stresses and displacements distributions are investigated. The presented results indicate that the material in-homogeneity has a significant influence on the electro-magneto-thermo-mechanical behaviors of the FGPM hollow sphere and should therefore be considered in its optimum design

Flexural Behavior of Functionally Graded-Graphene Reinforced Composite Plates

A first order shear deformation theory based finite element numerical investigation on flexure behaviour of functionally graded thin, moderately thick and thick composite plates reinforced with graphene platelets (GPLs) is presented in this paper. The maximum deflection plays a major role in the design of composite structures. Therefore, maximum deflection and percentage maximum deflection ratio of reinforced to unreinforced composite plate are investigated for a range of GPL distribution patterns along plan and thickness directions of the composite plate. Modified Halpin-Tsai equation is used to determine the effective Young’s modulus for each layer in thickness direction for different distribution patterns. The rule of mixture is used to calculate effective mass density and Poisson’s ratio for each layer. Initially, the results from this study are verified by comparing with the reported results from the literature. Thereafter, validated methodology is used to conduct case study for a simply supported plate, focusing on the effect of thickness, GPL distribution patterns along plan and thickness directions, percentage weight fraction of GPL on the maximum deflection and percentage maximum deflection ratio of reinforced to unreinforced composite plate. It is found that by adding just 1% weight fraction of GPL, the maximum deflection can be reduced by almost 65% to 90% for all thicknesses and distribution patterns considered

Bending, buckling, and forced vibration analyses of nonlocal nanocomposite microplate using TSDT considering MEE properties dependent to various volume fractions of CoFe₂O₄-BaTiO₃

In this article, the bending, buckling, free and forced vibration behavior of a nonlocal nanocomposite microplate using the third order shear deformation theory (TSDT) is presented. The magneto-electro-elastic (MEE) properties are dependent on various volume fractions of CoFe₂O₄-BaTiO₃. According to Maxwell’s equations and Hamilton’s principle, the governing differential equations are derived. These equations are discretized by using Navier’s method for an MEE nanocomposite Reddy plate. The numerical results show the influences of elastic foundation parameters such as aspect ratio, length to thickness ratio, electric and magnetic fields and various volume fractions of CoFe₂O₄-BaTiO₃ on deflection, critical buckling load and natural frequency. The natural frequency and critical buckling load increases with the increasing volume fraction of CoFe₂O₄-BaTiO₃, also the amplitude vibration decreases with an increase in the volume fraction. This model can be used for various nanocomposite structures. Also, a series of new experiments are recommended for future work

Nonlinear Buckling Analysis of Nano-composite Beam with Initial Geometrical Imperfection using Finite Element Method

In this research, the nonlinear buckling analysis of Functionally Graded (FG) nano-composite beam reinforced by various distributions of Boron Nitrid Nanotube (BNNT) is investigated under electro-thermodynamical loading with considering initial geometrical imperfection. The analysis is performed based on nonlocal elasticity theory and using the Finite Element Method (FEM). Various distributions of BNNT along the beam’s thickness are considered as uniform and decreasing-increasing functionally graded; and the extended mixture model is used to estimate the properties of nano-composite beam. The elastic medium around the smart nano-composite beam is modeled as elastic foundation. The governing equations of equilibrium are derived using energy method and nonlocal elasticity theory; and the critical buckling load is obtained for various boundary conditions such as simply-simply supported (S-S) and clamped-clamped (C-C) using the FEM. The results indicate that with an increase in the geometrical imperfection parameter, the stiffness of nano-composite beam increases and consequently the stability of the system increases. The effect of FG-X distribution type is more than uniform distributions. Also, the critical buckling load of nano-composite beam increases with an increase in the electric field and elastic foundation

Bending, buckling, and forced vibration analyses of nonlocal nanocomposite microplate using TSDT considering MEE properties dependent to various volume fractions of CoFe2O4-BaTiO3

In this article, the bending, buckling, free and forced vibration behavior of a nonlocal nanocomposite microplate using the third order shear deformation theory (TSDT) is presented. The magneto-electro-elastic (MEE) properties are dependent on various volume fractions of CoFe₂O₄-BaTiO₃. According to Maxwell’s equations and Hamilton’s principle, the governing differential equations are derived. These equations are discretized by using Navier’s method for an MEE nanocomposite Reddy plate. The numerical results show the influences of elastic foundation parameters such as aspect ratio, length to thickness ratio, electric and magnetic fields and various volume fractions of CoFe₂O₄-BaTiO₃ on deflection, critical buckling load and natural frequency. The natural frequency and critical buckling load increases with the increasing volume fraction of CoFe₂O₄-BaTiO₃, also the amplitude vibration decreases with an increase in the volume fraction. This model can be used for various nanocomposite structures. Also, a series of new experiments are recommended for future work