Gort Engovation Propulsion

Bradford, United Kingdom

Gort Engovation Propulsion

Bradford, United Kingdom
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Zidi M.,University Djilali Liabes | Tounsi A.,University Djilali Liabes | Houari M.S.A.,University Djilali Liabes | Adda Bedia E.A.,University Djilali Liabes | Anwar Beg O.,Gort Engovation Propulsion
Aerospace Science and Technology | Year: 2014

The bending response of functionally graded material (FGM) plate resting on elastic foundation and subjected to hygro-thermo-mechanical loading is studied. Using a four variable refined plate theory, both a quadratic variation of the transverse shear strains across the thickness and the zero traction boundary conditions on the top and bottom surfaces of the plate are satisfied without using shear correction factors. The number of independent unknowns of present theory is four, as against five in other shear deformation theories. The elastic coefficients, thermal coefficient and moisture expansion coefficient of the plate are assumed to be graded in the thickness direction. The elastic foundation is modelled as two-parameter Pasternak foundation. Numerical results are presented to verify the accuracy of present theory and the influences played by many parameters are investigated. The study is relevant to the simulation of rocket launch pad structures subjected to intense thermal loading. © 2014 Elsevier Masson SAS.


Belabed Z.,University Djilali Liabes | Ahmed Houari M.S.,University Djilali Liabes | Tounsi A.,University Djilali Liabes | Mahmoud S.R.,King Abdulaziz University | And 2 more authors.
Composites Part B: Engineering | Year: 2014

In this paper, an efficient and simple higher order shear and normal deformation theory is presented for functionally graded material (FGM) plates. By dividing the transverse displacement into bending, shear and thickness stretching parts, the number of unknowns and governing equations for the present theory is reduced, significantly facilitating engineering analysis. Indeed, the number of unknown functions involved in the present theory is only five, as opposed to six or even greater numbers in the case of other shear and normal deformation theories. The present theory accounts for both shear deformation and thickness stretching effects by a hyperbolic variation of all displacements across the thickness, and satisfies the stress-free boundary conditions on the upper and lower surfaces of the plate without requiring any shear correction factor. Equations of motion are derived from Hamilton's principle. Analytical solutions for the bending and free vibration analysis are obtained for simply supported plates. The obtained results are compared with 3-dimensional and quasi-3-dimensional solutions and those predicted by other plate theories. It can be concluded that the present theory is not only accurate but also simple in predicting the bending and free vibration responses of functionally graded plates. © 2013 Elsevier Ltd. All rights reserved.


Sid Ahmed Houari M.,University Djilali Liabes | Tounsi A.,University Djilali Liabes | Anwar Beg O.,Gort Engovation Propulsion
International Journal of Mechanical Sciences | Year: 2013

A new higher order shear and normal deformation theory is developed to simulate the thermoelastic bending of functionally graded material (FGM) sandwich plates. By dividing the transverse displacement into bending, shear and thickness stretching parts, the number of unknowns and governing equations for the present theory is reduced, significantly facilitating engineering analysis. Indeed, the number of unknown functions involved in the present theory is only five, as opposed to six or even greater numbers in the case of other shear and normal deformation theories. The present theory accounts for both shear deformation and thickness stretching effects by a sinusoidal variation of all displacements across the thickness, and satisfies the stress-free boundary conditions on the upper and lower surfaces of the plate without requiring any shear correction factor. The sandwich plate faces are assumed to have isotropic, two-constituent material distribution through the thickness, and the material properties are assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and composed of an isotropic ceramic material. The influences of thickness stretching, shear deformation, thermal load, plate aspect ratio, side-to-thickness ratio, and volume fraction distribution on plate bending characteristics are studied in detail. Numerical examples are presented to verify the accuracy of the present theory. The present study is relevant to aerospace, chemical process and nuclear engineering structures which may be subjected to intense thermal loads. © 2013 Elsevier Ltd.


Chaht F.L.,University Djilali Liabes | Kaci A.,University Djilali Liabes | Houari M.S.A.,University Djilali Liabes | Tounsi A.,University Djilali Liabes | And 3 more authors.
Steel and Composite Structures | Year: 2015

This paper addresses theoretically the bending and buckling behaviors of size-dependent nanobeams made of functionally graded materials (FGMs) including the thickness stretching effect. The size-dependent FGM nanobeam is investigated on the basis of the nonlocal continuum model. The nonlocal elastic behavior is described by the differential constitutive model of Eringen, which enables the present model to become effective in the analysis and design of nanostructures. The present model incorporates the length scale parameter (nonlocal parameter) which can capture the small scale effect, and furthermore accounts for both shear deformation and thickness stretching effects by virtue of a sinusoidal variation of all displacements through the thickness without using shear correction factor. The material properties of FGM nanobeams are assumed to vary through the thickness according to a power law. The governing equations and the related boundary conditions are derived using the principal of minimum total potential energy. A Navier-type solution is developed for simply-supported boundary conditions, and exact expressions are proposed for the deflections and the buckling load. The effects of nonlocal parameter, aspect ratio and various material compositions on the static and stability responses of the FGM nanobeam are discussed in detail. The study is relevant to nanotechnology deployment in for example aircraft structures. Copyright © 2015 Techno-Press, Ltd.


Beg O.A.,Gort Engovation Propulsion | Prasad V.R.,Madanapalle Institute of Technology and Science | Vasu B.,Madanapalle Institute of Technology and Science
Journal of Mechanics in Medicine and Biology | Year: 2013

A mathematical model has been developed for steady-state boundary layer flow of a nanofluid past an impermeable vertical flat wall in a porous medium saturated with a water-based dilute nanofluid containing oxytactic microorganisms. The nanoparticles were distributed sufficiently to permit bioconvection. The product of chemotaxis constant and maximum cell swimming speed was assumed invariant. Using appropriate transformations, the partial differential conservation equations were non-dimensionalised to yield a quartet of coupled, non-linear ordinary differential equations for momentum, energy, nanoparticle concentration and dimensionless motile microorganism density, with appropriate boundary conditions. The dominant parameters emerging in the normalised model included the bioconvection Lewis number, bioconvection Peclet number, Lewis number, buoyancy ratio parameter, Brownian motion parameter, thermophoresis parameter, local Darcy-Rayleigh number and the local Peclet number. An implicit numerical solution to the well-posed two-point non-linear boundary value problem is developed using the well-tested and highly efficient Keller box method. Computations are validated with the Nakamura tridiagonal implicit finite difference method, demonstrating excellent agreement. Nanoparticle concentration and temperature were found to be generally enhanced through the boundary layer with increasing bioconvection Lewis number, whereas dimensionless motile microorganism density was only increased closer to the wall. Temperature, nanoparticle concentration and dimensionless motile microorganism density were all greatly increased with a rise in Peclet number. Temperature and dimensionless motile microorganism density were reduced with increasing buoyancy parameter, whereas nanoparticle concentration was increased. The present study found applications in the fluid mechanical design of microbial fuel cell and bioconvection nanotechnological devices. © World Scientific Publishing Company.

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