The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Mohammad Reza Eslami - One of the best experts on this subject based on the ideXlab platform.
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buckling analysis of a functionally graded thin circular plate made of saturated porous materials
Journal of Engineering Mechanics-asce, 2014Co-Authors: M. Jabbari, A. Mojahedin, A R Khorshidvand, Mohammad Reza EslamiAbstract:AbstractThis study presents the buckling analysis of a radially loaded, solid, circular plate made of porous material. Properties of the plate vary across the thickness. The edge of the plate is either simply supported or clamped and the plate is assumed to be geometrically perfect. The geometrical nonlinearities are considered in the Love-Kirchhoff Hypothesis sense. The equilibrium and stability equations, derived through the variational formulation, are used to determine the prebuckling forces and critical buckling loads. The equations are based on the Sanders nonlinear strain-displacement relation. The porous plate is assumed to be of the form where pores are saturated with fluid. The results obtained for porous plates are compared with the homogeneous and porous/nonlinear, symmetric distribution, circular plates.
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Thermal Buckling Analysis of Functionally Graded Thin Circular Plate Made of Saturated Porous Materials
Journal of Thermal Stresses, 2013Co-Authors: M. Jabbari, A. Mojahedin, M. Hashemitaheri, Mohammad Reza EslamiAbstract:This study presents the buckling analysis of thermal loaded solid circular plate made of porous material. It is assumed that the material properties of the porous plate vary across the thickness. The edge of the plate is clamped and the plate is assumed to be geometrically perfect. The geometrical nonlinearities are considered in the Love–Kirchhoff Hypothesis sense. Equilibrium and stability equations, derived through the variational formulation, are used to determine the prebuckling temperatures and critical buckling temperatures. The equations are based on the Sanders non-linear strain-displacement relation.The porous plate is assumed of the form where pores are saturated with fluid. Also, the effect of pores distribution and thermal distribution on the critical buckling temperature is investigated.
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THERMOELASTIC STABILITY OF ORTHOTROPIC CIRCULAR PLATES
Journal of Thermal Stresses, 2002Co-Authors: Mohammad Mahdi Najafizadeh, Mohammad Reza EslamiAbstract:In this article the thermoelastic buckling of a circular orthotropic composite plate is discussed. The plate is assumed to be geometrically perfect. The equilibrium and stability equations, derived via variational formulations, are used to determine the prebuckling forces and the buckling temperatures. The equations are based on the Love-Kirchhoff Hypothesis and Sanders' nonlinear strain-displacement relation. Critical buckling temperatures associated with the uniform temperature rise, gradient through-the-thickness temperature, and linear temperature variation along the radius are obtained. The results are validated for the first type of loading with the known data in literature.
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Buckling analysis of circular plates of functionally graded materials under uniform radial compression
International Journal of Mechanical Sciences, 2002Co-Authors: Mohammad Mahdi Najafizadeh, Mohammad Reza EslamiAbstract:This study presents the buckling analysis of radially loaded solid circular plate made of functionally graded material. The edge of the plate is either simply supported or clamped and the plate is assumed to be geometrically perfect. The equilibrium and stability equations, derived through variational formulation, are used to determine the prebuckling forces and critical buckling loads. The equations are based on Love–Kirchhoff Hypothesis and the Sander's non-linear strain-displacement relation. The results are verified with the known results in the literature.
P Areias - One of the best experts on this subject based on the ideXlab platform.
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development of shear locking free shell elements using an enhanced assumed strain formulation
International Journal for Numerical Methods in Engineering, 2002Co-Authors: Renato Natal Jorge, R. A. Fontes Valente, P AreiasAbstract:The degenerated approach for shell elements of Ahmad and co-workers is revisited in this paper. To avoid transverse shear locking effects in four-node bilinear elements, an alternative formulation based on the enhanced assumed strain (EAS) method of Simo and Rifai is proposed directed towards the transverse shear terms of the strain field. In the first part of the work the analysis of the null transverse shear strain subspace for the degenerated element and also for the selective reduced integration (SRI) and assumed natural strain (ANS) formulations is carried out. Locking effects are then justified by the inability of the null transverse shear strain subspace, implicitly defined by a given finite element, to properly reproduce the required displacement patterns. Illustrating the proposed approach, a remarkably simple single-element test is described where ANS formulation fails to converge to the correct results, being characterized by the same performance as the degenerated shell element. The adequate enhancement of the null transverse shear strain subspace is provided by the EAS method, enforcing Kirchhoff Hypothesis for low thickness values and leading to a framework for the development of shear-locking-free shell elements. Numerical linear elastic tests show improved results obtained with the proposed formulation. Copyright © 2001 John Wiley & Sons, Ltd.
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Development of shear locking‐free shell elements using an enhanced assumed strain formulation
International Journal for Numerical Methods in Engineering, 2001Co-Authors: Renato Natal Jorge, R. A. Fontes Valente, P AreiasAbstract:The degenerated approach for shell elements of Ahmad and co-workers is revisited in this paper. To avoid transverse shear locking effects in four-node bilinear elements, an alternative formulation based on the enhanced assumed strain (EAS) method of Simo and Rifai is proposed directed towards the transverse shear terms of the strain field. In the first part of the work the analysis of the null transverse shear strain subspace for the degenerated element and also for the selective reduced integration (SRI) and assumed natural strain (ANS) formulations is carried out. Locking effects are then justified by the inability of the null transverse shear strain subspace, implicitly defined by a given finite element, to properly reproduce the required displacement patterns. Illustrating the proposed approach, a remarkably simple single-element test is described where ANS formulation fails to converge to the correct results, being characterized by the same performance as the degenerated shell element. The adequate enhancement of the null transverse shear strain subspace is provided by the EAS method, enforcing Kirchhoff Hypothesis for low thickness values and leading to a framework for the development of shear-locking-free shell elements. Numerical linear elastic tests show improved results obtained with the proposed formulation. Copyright © 2001 John Wiley & Sons, Ltd.
J G Simmonds - One of the best experts on this subject based on the ideXlab platform.
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A Simple Nonlinear Thermodynamic Theory of Arbitrary Elastic Beams
Journal of Elasticity, 2005Co-Authors: J G SimmondsAbstract:A ‘classical’ theory of beams (i.e., a theory in which the basic kinetic variables are a stress resultant and a stress couple) undergoing elastic, thermodynamic processes is developed by first deriving exact beamlike (one-dimensional) equations of motion and a beamlike Second Law (Clausius–Duhem inequality) by descent from three-dimensions. Then what may be considered as the three basic assumptions of a classical theory are introduced: an assumed form of the First Law (conservation of energy), a relaxed form of the Second Law, and a general form of the constitutive relations. Throughout, detailed specification of geometry, kinematics, or constitution is minimized. It is shown how the kinematic Kirchhoff Hypothesis may be avoided by first introducing a mixed-energy density and then imposing a logically more satisfying constitutive Kirchhoff Hypothesis.
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rotary inertia in the classical nonlinear theory of shells and the constitutive non kinematic Kirchhoff Hypothesis
Journal of Applied Mechanics, 2001Co-Authors: J G SimmondsAbstract:A general nonlinear theory of isothermal shells is presented in which the only approximations occur in the conservation of energy and in the consequent constitutive relations, which include expressions for the shell velocity and spin. No thickness expansions or kinematic hypotheses are made. The introduction of a dynamic mixed-energy density avoids ill-conditioning associated with near inextensional bending or negligible rotational momentum. It is shown that a variable scalar rotary inertia coefficient exists that minimizes the difference between the exact kinetic-energy density and that delivered by shell theory. Finally, it is shown how specialization of the dynamic mixed-energy density provides a simple and logical way to introduce a constitutive form of the Kirchhoff Hypothesis, thus avoiding certain unnecessary constraints (such as no thickness changes) imposed by the classical kinematic Kirchhoff Hypothesis.
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simplifications under the Kirchhoff Hypothesis of taber s nonlinear theory for the axisymmetric bending and torsion of elastic shells of revolution
International Journal of Solids and Structures, 1991Co-Authors: R England, J G SimmondsAbstract:Abstract We show that, under the Kirchhoff Hypothesis, Taber's recent theory for the simultaneous axisymmetric bending and torsion of shells of revolution undergoing large strains can be simplified considerably. In general, his 33 equations can be reduced to four first-order ordinary differential equations and two algebraic equations for six unknowns. For small strains, the equations can be reduced further to two coupled nonlinear equations for the meridional angle of rotation and a stress function, as in Reissner's theory of torsionless, axisymmetric deformation.
Renato Natal Jorge - One of the best experts on this subject based on the ideXlab platform.
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development of shear locking free shell elements using an enhanced assumed strain formulation
International Journal for Numerical Methods in Engineering, 2002Co-Authors: Renato Natal Jorge, R. A. Fontes Valente, P AreiasAbstract:The degenerated approach for shell elements of Ahmad and co-workers is revisited in this paper. To avoid transverse shear locking effects in four-node bilinear elements, an alternative formulation based on the enhanced assumed strain (EAS) method of Simo and Rifai is proposed directed towards the transverse shear terms of the strain field. In the first part of the work the analysis of the null transverse shear strain subspace for the degenerated element and also for the selective reduced integration (SRI) and assumed natural strain (ANS) formulations is carried out. Locking effects are then justified by the inability of the null transverse shear strain subspace, implicitly defined by a given finite element, to properly reproduce the required displacement patterns. Illustrating the proposed approach, a remarkably simple single-element test is described where ANS formulation fails to converge to the correct results, being characterized by the same performance as the degenerated shell element. The adequate enhancement of the null transverse shear strain subspace is provided by the EAS method, enforcing Kirchhoff Hypothesis for low thickness values and leading to a framework for the development of shear-locking-free shell elements. Numerical linear elastic tests show improved results obtained with the proposed formulation. Copyright © 2001 John Wiley & Sons, Ltd.
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Development of shear locking‐free shell elements using an enhanced assumed strain formulation
International Journal for Numerical Methods in Engineering, 2001Co-Authors: Renato Natal Jorge, R. A. Fontes Valente, P AreiasAbstract:The degenerated approach for shell elements of Ahmad and co-workers is revisited in this paper. To avoid transverse shear locking effects in four-node bilinear elements, an alternative formulation based on the enhanced assumed strain (EAS) method of Simo and Rifai is proposed directed towards the transverse shear terms of the strain field. In the first part of the work the analysis of the null transverse shear strain subspace for the degenerated element and also for the selective reduced integration (SRI) and assumed natural strain (ANS) formulations is carried out. Locking effects are then justified by the inability of the null transverse shear strain subspace, implicitly defined by a given finite element, to properly reproduce the required displacement patterns. Illustrating the proposed approach, a remarkably simple single-element test is described where ANS formulation fails to converge to the correct results, being characterized by the same performance as the degenerated shell element. The adequate enhancement of the null transverse shear strain subspace is provided by the EAS method, enforcing Kirchhoff Hypothesis for low thickness values and leading to a framework for the development of shear-locking-free shell elements. Numerical linear elastic tests show improved results obtained with the proposed formulation. Copyright © 2001 John Wiley & Sons, Ltd.
M. Jabbari - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Stability of Functionally Graded Soft Ferromagnetic Porous Rectangular Plate
Journal of Solid Mechanics, 2015Co-Authors: M. Jabbari, A. Mojahedin, M Haghi Choobar, E. Farzaneh JoubanehAbstract:This study presents critical buckling of functionally graded soft ferromagnetic porous (FGFP) rectangular plates, under magnetic field with simply supported boundary condition. Equilibrium and stability equations of a porous rectangular plate in transverse magnetic field are derived. The geometrical nonlinearities are considered in the Love-Kirchhoff Hypothesis sense. The formulations are compared to those of homogeneous isotropic plates were given in the literature. In this paper the effect of pore pressure on critical magnetic field of plate and the effect of important parameters of poroelastic material on buckling capacity are investigated. Also the compressibility of fluid and porosity on the buckling strength are studied.
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Buckling analysis of thin circular FG plates made of saturated porous-soft ferromagnetic materials in transverse magnetic field
Thin-walled Structures, 2014Co-Authors: M. Jabbari, A. Mojahedin, M. HaghiAbstract:Abstract This study presents the buckling analysis of soft ferromagnetic FG circular plates made of poro material. Equilibrium and stability equations of a poro circular plate in transverse magnetic field are derived. This study analyzes the poroelastic instability of clamped edge ferromagnetic plates subjected to magnetic loadings. The geometrical nonlinearities are considered in the Love–Kirchhoff Hypothesis sense. In this paper the effect of pore pressure on critical magnetic field of plate and the effect of important parameters of poroelastic material on buckling capacity are investigated. Also the compressibility of fluid and porosity on the buckling strength are being investigated.
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buckling analysis of a functionally graded thin circular plate made of saturated porous materials
Journal of Engineering Mechanics-asce, 2014Co-Authors: M. Jabbari, A. Mojahedin, A R Khorshidvand, Mohammad Reza EslamiAbstract:AbstractThis study presents the buckling analysis of a radially loaded, solid, circular plate made of porous material. Properties of the plate vary across the thickness. The edge of the plate is either simply supported or clamped and the plate is assumed to be geometrically perfect. The geometrical nonlinearities are considered in the Love-Kirchhoff Hypothesis sense. The equilibrium and stability equations, derived through the variational formulation, are used to determine the prebuckling forces and critical buckling loads. The equations are based on the Sanders nonlinear strain-displacement relation. The porous plate is assumed to be of the form where pores are saturated with fluid. The results obtained for porous plates are compared with the homogeneous and porous/nonlinear, symmetric distribution, circular plates.
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Thermal Buckling Analysis of Functionally Graded Thin Circular Plate Made of Saturated Porous Materials
Journal of Thermal Stresses, 2013Co-Authors: M. Jabbari, A. Mojahedin, M. Hashemitaheri, Mohammad Reza EslamiAbstract:This study presents the buckling analysis of thermal loaded solid circular plate made of porous material. It is assumed that the material properties of the porous plate vary across the thickness. The edge of the plate is clamped and the plate is assumed to be geometrically perfect. The geometrical nonlinearities are considered in the Love–Kirchhoff Hypothesis sense. Equilibrium and stability equations, derived through the variational formulation, are used to determine the prebuckling temperatures and critical buckling temperatures. The equations are based on the Sanders non-linear strain-displacement relation.The porous plate is assumed of the form where pores are saturated with fluid. Also, the effect of pores distribution and thermal distribution on the critical buckling temperature is investigated.
