Author
Hassan Haddadpour
Bio: Hassan Haddadpour is an academic researcher from Sharif University of Technology. The author has contributed to research in topics: Aeroelasticity & Galerkin method. The author has an hindex of 28, co-authored 125 publications receiving 2823 citations.
Papers published on a yearly basis
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01 Jan 2008
TL;DR: In this article, a beam theory different from the traditional first-order shear deformation beam theory is used to analyze free vibration of functionally graded beams, where the beam properties are varied through the thickness following a simple power law distribution in terms of volume fraction of material constituents.
Abstract: Abstract A new beam theory different from the traditional first-order shear deformation beam theory is used to analyze free vibration of functionally graded beams. The beam properties are assumed to be varied through the thickness following a simple power law distribution in terms of volume fraction of material constituents. It is assumed that the lateral normal stress of the beam is zero and the governing equations of motion are derived using Hamilton’s principle. Resulting system of ordinary differential equations of free vibration analysis is solved using an analytical method. Different boundary conditions are considered and comparisons are made among different beam theories. Also, the effects of boundary conditions, volume fraction and shear deformation on natural frequencies and mode shapes are investigated.
347 citations
TL;DR: In this paper, a beam theory different from the traditional first-order shear deformation beam theory is used to analyze free vibration of functionally graded beams, where the beam properties are varied through the thickness following a simple power law distribution in terms of volume fraction of material constituents.
312 citations
TL;DR: In this article, free vibration analysis of simply supported FG cylindrical shells for four sets of in-plane boundary conditions is performed, where the material properties are assumed to be temperature-dependant and gradually changed in the thickness direction of the shell.
Abstract: Free vibration analysis of simply supported FG cylindrical shells for four sets of in-plane boundary conditions is performed. The material properties are assumed to be temperature-dependant and gradually changed in the thickness direction of the shell. The effects of temperature rise are investigated by specifying arbitrary high temperature on the outer surface and the ambient temperature on the inner surface of the cylinder. Distribution of temperature across the shell thickness is found from steady state heat conduction only in the thickness direction. The equations of motion are based on Love's shell theory and the von Karman–Donnell-type of kinematic nonlinearity. The static analysis is first performed to determine the prestressed state induced by the thermal loadings, using the exact solution of the governing equations and then the equations of motion are solved by Galerkin's method. The results are obtained to indicate the effects of power law index on the natural frequencies and corresponding mode shapes in the thermal environment.
144 citations
TL;DR: In this article, the authors investigated the effect of van der Waals and Casimir forces on the pull-in instability of cantilever nano-actuators by considering their range of application.
Abstract: This paper investigates the effect of dispersion (van der Waals and Casimir) forces on the pull-in instability of cantilever nano-actuators by considering their range of application. Adomian decomposition is introduced to obtain an analytical solution of the distributed parameter model. Dispersion forces decrease the pull-in deflection and voltage of a nano-actuator. However, the fringing field increases the pull-in deflection while decreasing the pull-in voltage of the actuator. The minimum initial gap and the detachment length of the actuator that does not stick to the substrate due to van der Waals and Casimir attractions were determined. Furthermore, the proposed approach is capable of determining the stress distribution of the actuator at the onset of instability. It is seen that Casimir and van der Waals attractions effectively reduce the maximum value of stress resultants at the onset of instability. The results indicate that Adomian decomposition is a reliable method for simulating nano-structures at submicrometer ranges.
122 citations
TL;DR: In this article, the problem of nonlinear aeroelasticity of a general laminated composite plate in supersonic air flow is examined, where the classical plate theory along with the von-Karman nonlinear strains are used for structural modeling, and linear piston theory is used for aerodynamic modeling.
88 citations
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TL;DR: A review of the reported studies in the area of thermo-elastic and vibration analyses of functionally graded (FG) plates with an emphasis on the recent works published since 1998 is presented in this paper.
695 citations
TL;DR: In this article, the material properties of carbon nanotube-reinforced composites (FG-CNTRCs) are modeled through a micromechanical model based on the multi-scale approach.
465 citations
TL;DR: In this paper, the dynamic characteristics of functionally graded beam with material graduation in axially or transversally through the thickness based on the power law are presented. But the model is more effective for replacing the non-uniform geometrical beam with axially and transversely uniform geometrically graded beam.
458 citations
TL;DR: In this article, a non-classical microbeam model incorporating the material length scale parameter was proposed to capture the size effect of the FG microbeams and the governing equations and the related boundary conditions were derived using Hamilton's principle.
424 citations
TL;DR: In this article, the effect of thickness stretching in plate/shell structures made by materials which are functionally graded (FGM) in the thickness directions was evaluated by removing or retaining the transverse normal strain in the kinematics assumptions of various refined plate and shell theories.
Abstract: The present work evaluates the effect of thickness stretching in plate/shell structures made by materials which are functionally graded (FGM) in the thickness directions. That is done by removing or retaining the transverse normal strain in the kinematics assumptions of various refined plate/shell theories. Variable plate/shell models are implemented according to Carrera’s Unified Formulation. Plate/shell theories with constant transverse displacement are compared with the corresponding linear to fourth order of expansion in the thickness direction ones. Single-layered and multilayered FGM structures have been analyzed. A large numerical investigation, encompassing various plate/shell geometries as well as various grading rates for FGMs, has been conducted. It is mainly concluded that a refinements of classical theories that include additional in-plane variables could results meaningless unless transverse normal strain effects are taken into account.
373 citations