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    Asymmetric wave propagation in a transversely isotropic half-space in displacement potentials

    , Article International Journal of Engineering Science ; Volume 46, Issue 7 , 2008 , Pages 690-710 ; 00207225 (ISSN) Khojasteh, A ; Rahimian, M ; Eskandari, M ; Pak, R. Y. S ; Sharif University of Technology
    2008
    Abstract
    With the aid of a complete representation using two displacement potentials, an efficient and accurate analytical derivation of the fundamental Green's functions for a transversely isotropic elastic half-space subjected to an arbitrary, time-harmonic, finite, buried source is presented. The formulation includes a complete set of transformed stress-potential and displacement-potential relations that can be useful in a variety of elastodynamic as well as elastostatic problems. The present solutions are analytically in exact agreement with the existing solutions for a half-space with isotropic material properties. For the numerical evaluation of the inversion integrals, a quadrature scheme... 

    Elastic Analysis of Brazilian Test of Transversely Isotropic Material

    , M.Sc. Thesis Sharif University of Technology Farajpour Niri, Farid (Author) ; Eskandari, Morteza (Supervisor)
    Abstract
    In Former research we determinate elastic response of Brazilian Test of transversely Isotropic material . In Bio-mechanic science surveying mechanical properties and modeling biological organ such as bone , tooth and bio-material such as titanium, zirconium with application in joint replacement is very important . One of method to determine properties of bio-material which mostly has transversely Isotropic behavior is Brazilian Test. Also most rocks has transversely Isotropic behavior, so choosing efficient test is so important. In current issue , load apply in limited area and it is also considered friction in area of jaw loading area .By use of displacement potential function ... 

    Axisymmetric time-harmonic response of a transversely isotropic substrate-coating system

    , Article International Journal of Engineering Science ; Volume 45, Issue 2-8 , 2007 , Pages 272-287 ; 00207225 (ISSN) Shodja, H. M ; Eskandari, M ; Sharif University of Technology
    2007
    Abstract
    By virtue of a method of displacement potentials, an analytical treatment of the response of a transversely isotropic substrate-coating system subjected to axisymmetric time-harmonic excitations is presented. In determination of the corresponding elastic fields, infinite line integrals with singular complex kernels are encountered. Branch points, cuts, and poles along the path of integration are accounted for exactly, and the physical phenomena pertinent to wave propagation in the medium are also highlighted. For evaluation of the integrals at the singular points, an accurate analytical residual theory is presented. Comparisons with the existing numerical solutions for a two-layered... 

    Elastic Responses of a Transversely Isotropic Half-Space Reinforced by a Buried Extensible Membrane under Internal Loading

    , M.Sc. Thesis Sharif University of Technology Shahsavarian, Ali (Author) ; Eskandari, Morteza (Supervisor)
    Abstract
    In this research, a homogeneous elastic half-space with transversely isotropic behavior, reinforced by an isotropic thin membrane is investigated under static loading with an analytical approach. The membrane is considered as an infinite plane with a thickness of negligible and buried at the arbitrary depth from the surface of the half-space, also its flexural strength is neglected and only the in-plane stiffness is considered for it. The reinforced half-space is investigated under several concentrated and distributed static loads, which are applied to the surface of the half-space or buried at the depth of the membrane. The membrane is first modeled as a three-dimensional elastic layer and... 

    3D Elasticity Buckling Solution for Transversely Isotropic Functionally Graded Rectangular Plates by Displacement Potential Function

    , M.Sc. Thesis Sharif University of Technology Jafari, Ali (Author) ; Khaloo, Alireza (Supervisor) ; Navayi Neya, Bahram (Co-Supervisor)
    Abstract
    The importance of transversely isotropic and functionally graded materials and also plates in industry necessitates studies on these kinds of structures. This study works on the buckling of simply supported rectangular transversely isotropic FGM plates subjected to in-plane uniaxial or biaxial static loads. For this purpose, discretization method is applied and the aforesaid inhomogeneous plate is divided into arbitrary number of sublayers parametrically (N). With the help of displacement potential functions, coupled different equations for each sublayer are simplified to two uncoupled different equations in terms of the potential functions. These governing equations for transversely... 

    Surface waves on a half-space due to a time-harmonic loading on an inertial strip foundation

    , Article Journal of Vibration and Acoustics, Transactions of the ASME ; Volume 135, Issue 5 , 2013 ; 10489002 (ISSN) Dehestani, M ; Vafai, A ; Choobbasti, A. J ; Malidarreh, N. R ; Szidarovszky, F ; Sharif University of Technology
    2013
    Abstract
    An analytical approach has been applied to obtain the solution of Navier's equation for a homogeneous, isotropic half-space under an inertial foundation subjected to a timeharmonic loading. Displacement potentials were used to change the Navier's equation to a system of wave-type equations. Calculus of variation was employed to demonstrate the contribution of the foundation's inertial effects as boundary conditions. Use of the Fourier transformation method for the system of Poisson-type equations and applying the boundary conditions yielded the transformed surface displacement field. Direct contour integration has been employed to achieve the surface waves. In order to clarify the... 

    Three-dimensional dynamic Green's functions in transversely isotropic tri-materials

    , Article Applied Mathematical Modelling ; Volume 37, Issue 5 , March , 2013 , Pages 3164-3180 ; 0307904X (ISSN) Khojasteh, A ; Rahimian, M ; Eskandari, M ; Sharif University of Technology
    2013
    Abstract
    An analytical derivation of the elastodynamic fundamental solutions for a transversely isotropic tri-material full-space is presented by means of a complete representation using two displacement potentials. The complete set of three-dimensional point-load, patch-load, and ring-load Green's functions for stresses and displacements are given, for the first time, in the complex-plane line-integral representations. The formulation includes a complete set of transformed stress-potential and displacement-potential relations in the framework of Fourier expansions and Hankel integral transforms, that is useful in a variety of elastodynamic as well as elastostatic problems. For the numerical... 

    Three-dimensional dynamic Green's functions for a multilayered transversely isotropic half-space

    , Article International Journal of Solids and Structures ; Volume 48, Issue 9 , 2011 , Pages 1349-1361 ; 00207683 (ISSN) Khojasteh, A ; Rahimian, M ; Eskandari, M ; Pak, R. Y. S ; Sharif University of Technology
    2011
    Abstract
    With the aid of a method of displacement potentials, an efficient and accurate analytical derivation of the three-dimensional dynamic Green's functions for a transversely isotropic multilayered half-space is presented. Constituted by proper algebraic factorizations, a set of generalized transmission-reflection matrices and internal source fields that are free of any numerically unstable exponential terms are proposed for effective computations of the potential solution. Three-dimensional point-load Green's functions for stresses and displacements are given, for the first time, in the complex-plane line-integral representations. The present formulations and solutions are analytically in exact... 

    Displacement potentials for functionally graded piezoelectric solids

    , Article Applied Mathematical Modelling ; Volume 52 , 2017 , Pages 458-469 ; 0307904X (ISSN) Samea, P ; Eskandari, M ; Ahmadi, S. F ; Sharif University of Technology
    Abstract
    Two new displacement potential functions are introduced for the general solution of a three-dimensional piezoelasticity problem for functionally graded transversely isotropic piezoelectric solids. The material properties vary continuously along the axis of symmetry of the medium. The four coupled equilibrium equations in terms of displacements and electric potential are reduced to two decoupled sixth- and second-order linear partial differential equations for the potential functions. The obtained results are verified with two limiting cases: (i) a functionally graded transversely isotropic medium, and (ii) a homogeneous transversely isotropic piezoelectric solid. The simplified relations... 

    Axisymmetric time-harmonic response of a surface-stiffened transversely isotropic half-space

    , Article Meccanica ; Volume 52, Issue 1-2 , 2017 , Pages 183-196 ; 00256455 (ISSN) Eskandari, M ; Samea, P ; Ahmadi, S. F ; Sharif University of Technology
    Abstract
    This study deals with the elastodynamic response of a surface-stiffened transversely isotropic half-space subjected to a buried time-harmonic normal load. The half-space is reinforced by a Kirchhoff thin plate on its surface. By virtue of a displacement potential function and appropriate time-harmonic Green’s functions of transversely isotropic half-spaces, a robust solution corresponding to two plate-medium bonding assumptions, namely (a) frictionless interface, and (b) perfectly bonded interface is obtained for the first time. All elastic fields of the problem are expressed explicitly in the form of semi-infinite line integrals. Results of some limiting cases including isotropic materials,... 

    On thermoelastic fields of a multi-phase inhomogeneity system with perfectly/imperfectly bonded interfaces

    , Article International Journal of Solids and Structures ; Volume 45, Issue 22-23 , 2008 , Pages 5831-5843 ; 00207683 (ISSN) Hatami Marbini, H ; Mohammadi Shodja, H ; Sharif University of Technology
    2008
    Abstract
    The stress fields of cylindrical and spherical multi-phase inhomogeneity systems with perfect or imperfect interfaces under uniform thermal and far-field mechanical loading conditions are investigated by use of the Boussinesq displacement potentials. The radius of the core inhomogeneity and the thickness of its surrounding coatings are arbitrary. The discontinuities in the tangential and normal components of the displacement at the imperfect interfaces are assumed to be proportional to the associated tractions. In this work, for the problems where the phases of the inhomogeneity system are homogeneous, the exact closed-form thermo-elastic solutions are presented. These solutions along with a... 

    Axisymmetric circular indentation of a half-space reinforced by a buried elastic thin film

    , Article Mathematics and Mechanics of Solids ; Vol. 19, issue. 6 , 2014 , p. 703-712 Ahmadi, S. F ; Eskandari, M ; Sharif University of Technology
    Abstract
    The analytical treatment of an axisymmetric rigid punch indentation of an isotropic half-space reinforced by a buried extensible thin film is addressed. With the aid of appropriate displacement potential functions, Hankel transforms, and some mathematical techniques, the mixed boundary value problem under consideration is reduced to a Fredholm integral equation of the second kind. The most interesting results of the problem, including the equivalent normal stiffness of the system and the contact stress distribution beneath the rigid punch, are expressed in terms of the solution of the obtained Fredholm integral equation. Some limiting cases corresponding to inextensible and extremely... 

    Green's functions of a surface-stiffened transversely isotropic half-space

    , Article International Journal of Solids and Structures ; Volume 49, Issue 23-24 , 2012 , Pages 3282-3290 ; 00207683 (ISSN) Eskandari, M ; Ahmadi, S. F ; Sharif University of Technology
    2012
    Abstract
    Green's functions of a transversely isotropic half-space overlaid by a thin coating layer are analytically obtained. The surface coating is modeled by a Kirchhoff thin plate perfectly bonded to the half-space. With the aid of superposition technique and employing appropriate displacement potential functions, the Green's functions are expressed in two parts; (i) a closed-form part corresponding to the transversely isotropic half-space with surface kinematic constraints, and (ii) a numerically evaluated part reflecting the interaction between the half-space and the plate in the form of semi-infinite integrals. Some limiting cases of the problem such as surface-stiffened isotropic half-space,... 

    Green's functions of an exponentially graded transversely isotropic half-space

    , Article International Journal of Solids and Structures ; Volume 47, Issue 11-12 , June , 2010 , Pages 1537-1545 ; 00207683 (ISSN) Eskandari, M ; Shodja, H. M ; Sharif University of Technology
    2010
    Abstract
    By virtue of a complete set of displacement potential functions and Hankel transform, the analytical expressions of Green's function of an exponentially graded elastic transversely isotropic half-space is presented. The given solution is analytically in exact agreement with the existing solution for a homogeneous transversely isotropic half-space. Employing a robust asymptotic decomposition technique, the Green's function is decomposed to the closed-form Green's function corresponding to the homogeneous transversely isotropic half-space and grading term with strong decaying integrands. This representation is very useful for numerical methods which are based on boundary-integral formulations...