Mechanical buckling of functionally graded plates using a refined higher-order shear and normal deformation plate theory

Zenkour, A.M.,Aljadani, M.H. Techno-Press 2018 Advances in aircraft and spacecraft science Vol.5 No.6

Mechanical buckling of a rectangular functionally graded plate is obtained in the current paper using a refined higher-order shear and normal deformation theory. The impact of transverse normal strain is considered. The material properties are microscopically inhomogeneous and vary continuously based on a power law form in spatial direction. Navier's procedure is applied to examine the mechanical buckling behavior of a simply supported FG plate. The mechanical critical buckling subjected to uniaxial and biaxial compression loads are determined. The numerical investigation are compared with the numerical results in the literature. The influences of geometric parameters, power law index and different loading conditions on the critical buckling are studied.

State space approach for the vibration of nanobeams based on the nonlocal thermoelasticity theory without energy dissipation

A. M. Zenkour,A. E. Abouelregal,K. A. Alnefaie,N. H. Abu-Hamdeh,A. A. Aljinaidi,E. C. Aifantis 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.7

In this article, an Euler-Bernoulli beam model based upon nonlocal thermoelasticity theory without energy dissipation is used to studythe vibration of a nanobeam subjected to ramp-type heating. Classical continuum theory is inherently size independent, while nonlocalelasticity exhibits size dependence. Among other things, this leads to a new expression for the effective nonlocal bending moment ascontrasted to its classical counterpart. The thermal problem is addressed in the context of the Green-Naghdi (GN) theory of heat transportwithout energy dissipation. The governing partial differential equations are solved in the Laplace transform domain by the state spaceapproach of modern control theory. Inverse of Laplace transforms are computed numerically using Fourier expansion techniques. Theeffects of nonlocality and ramping time parameters on the lateral vibration, temperature, displacement and bending moment are discussed.

Viscoelastic analysis of an exponentially graded sandwich plate

A. M. Zenkour 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.3

Bending response of an exponentially graded fiber-reinforced viscoelastic (EGFV) sandwich plate is investigated using various plate theories. The plate consists of viscoelastic material faces and an elastic material core. The effective moduli and Illyushin’s approximation methods are used to solve the equations governing the bending of simply-support EGFV sandwich plates. Numerical results for deflections and stresses are presented and some of them are compared. The effects due to aspect ratio, side-to-thickness ratio and constitutive parameter as well as time parameter are all investigated. Concluding remarks are made.

Effects of variable harmonic heat and photothermal elasticity on an infinitely long solid semiconductor cylinder

Zenkour A. M.,Abouelregal A. E. 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.8

In this research, photo-thermoelasticity theory with phase lags was introduced and applied to an infinite semiconductor body in the form of a solid cylinder. The body is constricted and exposed to harmonic shifting heat. The essential equations overseeing the problem are unraveled utilizing the Laplace transform. To locate the analytical formulae of the physical amounts and to discover inverse Laplace transforms, we utilized a numerical technique. The detailed examination of the impacts of phase lags and the angular frequency of the thermal vibration on the absolute temperature, stresses, absolute carrier density, and displacement is considered.

Effect of Temperature-dependent Physical Properties on Nanobeam Structures Induced by Ramp-type Heating

A. M. Zenkour 대한토목학회 2017 KSCE Journal of Civil Engineering Vol.21 No.5

The classical Euler-Bernoulli beam theory based upon the nonlocal theory of thermoelasticity is constructed and employed to investigate the vibrating nanobeam due to a ramp-type heating. The thermal conductivity and modulus of elasticity are taken as temperature-dependent functions. The generalized theory of thermoelasticity with Dual-Phase-Lags (DPLs) model is also employed to solve the problem. Analytical and numerical techniques based on Laplace transforms and their inversions are used to calculate the vibrational deflection and temperature of the nanobeam. The effects of the PLs and ramping-time parameters on the lateral vibration, the temperature, the displacement and the flexure moment of the nanobeam are investigated. Some plots have been presented for comparison purposes to estimate the effects of the nonlocal parameter on the field quantities. For the sake of completeness a comparison is also made between the present results and those obtained in the case of temperature-independent thermal and mechanical properties

Generalized thermodiffusion for an unbounded body with a spherical cavity subjected to periodic loading

A. M. Zenkour,D. S. Mashat,A. E. Abouelregal 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.3

In this paper, a general solution to the field equations of generalized thermodiffusion in an infinite thermoelastic body with a spherical cavity has been obtained in the context of the theory of generalized thermoelastic diffusion. The bounding surface of the sphere is subjected to periodic loading and the temperature and chemical potential are assumed to be zero on the curved surface. The generalized theory of thermoelasticity is applied to account for finite velocity of heat propagation. The closed form solutions for distributions of displacement, temperature and stresses are obtained. The solutions valid in the case of small frequency are deduced and the results are compared with the corresponding results obtained in other generalized thermoelasticity theories. Numerical results applicable to a copper-like material are also presented graphically and the nature of variations of the physical quantities with radial coordinate and with frequency of vibration is analyzed.

Semi-empirical and Efficient Solutions for FGPM Hollow Spheres in Hygrothermal Environment

M. N. M. Allam,R. Tantawy,A. M. Zenkour 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.5

This paper presents semi-analytical solutions for functionally graded piezoelectric hollow spheres. The hollow sphere is subjected to pressure on the boundary surface, electric potentials difference between the outer and inner surfaces, and uniform distribution of hygrothermal effect. It is assumed that the material properties of the sphere are graded in the radial direction according to a power law distribution of the volume fraction of the constituents. Some cases of boundary conditions are presented for stresses, electric potentials and displacement. Finally, numerical results for radial displacement, electric potential and stresses are carried out and discussed. The effects of different parameters are investigated. It can be concluded that the gradient of the material properties have particular influence in modern engineering design.

Photo-thermo-elastic interaction in a semiconductor material with two relaxation times by a focused laser beam

Jahangir, A.,Tanvir, F.,Zenkour, A.M. Techno-Press 2020 Advances in aircraft and spacecraft science Vol.7 No.1

The effect of relaxation times is studied on plane waves propagating through semiconductor half-space medium by using the eigen value approach. The bounding surface of the half-space is subjected to a heat flux with an exponentially decaying pulse and taken to be traction free. Solution of the field variables are obtained in the form of series for a general semiconductor medium. For numerical values, Silicon is considered as a semiconducting material. The results are represented graphically to assess the influences of the thermal relaxations times on the plasma, thermal, and elastic waves.

Magneto-thermo-elastic response of exponentially graded piezoelectric hollow spheres

Allam, M.N.M.,Tantawy, R.,Zenkour, A.M. Techno-Press 2018 Advances in computational design Vol.3 No.3

This article presents a semi-analytical solution for an exponentially graded piezoelectric hollow sphere. The sphere interacts with electric displacement, elastic deformations, electric potentials, magneto-thermo-elasticity, and hygrothermal influences. The hollow sphere may be standing under both mechanical and electric potentials. Electro-magneto-elastic behavior of magnetic field vector can be described in the hollow sphere. All material, thermal and magnetic properties of hollow sphere are supposed to be graded in radial direction. A semi-analytical technique is improved to deduce all fields in which different boundary conditions for radial stress and electric potential are presented. Numerical examples for radial displacement, radial and hoop stresses, and electric potential are investigated. The influence of many parameters is studied. It is seen that the gradation of all material, thermal and magnetic properties has particular effectiveness in many applications of modern technology.

Variability of thermal properties for a thermoelastic loaded nanobeam excited by harmonically varying heat

Abouelregal, A.E.,Zenkour, A.M. Techno-Press 2017 Smart Structures and Systems, An International Jou Vol.20 No.4

This work produces a new model of nonlocal thermoelastic nanobeams of temperature-dependent physical properties. A nanobeam is excited by harmonically varying heat and subjected to an exponential decaying time varying load. The analytical solution is obtained by means of Laplace transform method in time domain. Inversions of transformed solutions have been preceded by using calculus of residues. Effects of nonlocal parameter, variability thermal conductivity, varying load and angular frequency of thermal vibration on studied fields of nanobeam are investigated and discussed.