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Q Wang - One of the best experts on this subject based on the ideXlab platform.

  • buckling and vibration analysis of a pressurized cnt reinforced Functionally graded truncated conical shell under an axial compression using hdq method
    Computer Methods in Applied Mechanics and Engineering, 2016
    Co-Authors: M Mehri, Hamed Asadi, Q Wang
    Abstract:

    Abstract The present research deals with bifurcation and vibration responses of a composite truncated conical shell with embedded single-walled carbon nanotubes (SWCNTs) subjected to an external pressure and axial compression simultaneously. The distribution of reinforcements through the thickness of the shell is assumed to be either uniform or Functionally graded. The equations of motion are established using Green–Lagrange type nonlinear kinematics within the framework of Novozhilov nonlinear shell theory. Linear membrane prebuckling analysis is conducted to extract the prebuckling deformations. The stability equations are derived by applying the adjacent equilibrium criterion to the prebuckling state of the conical shell. A semi-analytical solution on the basis of the trigonometric expansion through the circumferential direction along with the harmonic differential quadrature (HDQ) discretization in the meridional direction is developed. A series of comparison studies are carried out to assure the accuracy and the convergence of the HDQ method. The research indicates that the superb accuracy and efficiency of solutions with few grid points are attributed to the higher-order harmonic Approximation Function in the HDQ method. Parametric studies are also presented to investigate the influence of boundary conditions, semi-vertex angle of the cone, volume fraction and distribution of CNTs on stability and vibration characteristics of the truncated conical shell. The results show that both volume fraction and distribution of CNTs play a pivotal role in the natural frequencies, buckling mode and buckling loads of the FG-CNTRC truncated conical shell.

M Mehri - One of the best experts on this subject based on the ideXlab platform.

  • Computationally efficient model for flow-induced instability of CNT reinforced Functionally graded truncated conical curved panels subjected to axial compression
    Computer Methods in Applied Mechanics and Engineering, 2017
    Co-Authors: M Mehri, Hamed Asadi, M.a. Kouchakzadeh
    Abstract:

    Abstract As a first endeavor, the aeroelastic responses of Functionally graded carbon nanotube reinforced composite (FG-CNTRC) truncated conical curved panels subjected to aerodynamic load and axial compression are investigated. The nonlinear dynamic equations of FG-CNTRC conical curved panels are derived according to Green’s strains and the Novozhilov nonlinear shell theory. The aerodynamic load is estimated in accordance with the quasi-steady Krumhaar’s modified supersonic piston theory by taking into account the effect of the panel curvature. Matrix transform method along with the harmonic differential quadrature method (HDQM) are employed to solve the nonlinear equations of motion of the FG-CNTRC truncated conical curved panel. The advantage of the matrix transform method is that we only need to discretize the meridional direction. Effects of semi-vertex angle of the cone, subtended angle of the panel, boundary conditions, geometrical parameters, volume fraction and distribution of CNT, and Mach number on the aeroelastic characteristics of the FG-CNTRC conical curved panel are put into evidence via a set of parametric studies and pertinent conclusions are outlined. The results prove that the panels with different FG distributions have different critical dynamic pressure. It is found that the semi-vertex and subtended angles play a pivotal role in changing the critical circumferential mode number of the flutter instability. Besides, the research shows that the superb efficiency of proposed method with few grid points, which requires less CPU time, are attributed to the matrix transform method and the higher-order harmonic Approximation Function in the HDQM.

  • buckling and vibration analysis of a pressurized cnt reinforced Functionally graded truncated conical shell under an axial compression using hdq method
    Computer Methods in Applied Mechanics and Engineering, 2016
    Co-Authors: M Mehri, Hamed Asadi, Q Wang
    Abstract:

    Abstract The present research deals with bifurcation and vibration responses of a composite truncated conical shell with embedded single-walled carbon nanotubes (SWCNTs) subjected to an external pressure and axial compression simultaneously. The distribution of reinforcements through the thickness of the shell is assumed to be either uniform or Functionally graded. The equations of motion are established using Green–Lagrange type nonlinear kinematics within the framework of Novozhilov nonlinear shell theory. Linear membrane prebuckling analysis is conducted to extract the prebuckling deformations. The stability equations are derived by applying the adjacent equilibrium criterion to the prebuckling state of the conical shell. A semi-analytical solution on the basis of the trigonometric expansion through the circumferential direction along with the harmonic differential quadrature (HDQ) discretization in the meridional direction is developed. A series of comparison studies are carried out to assure the accuracy and the convergence of the HDQ method. The research indicates that the superb accuracy and efficiency of solutions with few grid points are attributed to the higher-order harmonic Approximation Function in the HDQ method. Parametric studies are also presented to investigate the influence of boundary conditions, semi-vertex angle of the cone, volume fraction and distribution of CNTs on stability and vibration characteristics of the truncated conical shell. The results show that both volume fraction and distribution of CNTs play a pivotal role in the natural frequencies, buckling mode and buckling loads of the FG-CNTRC truncated conical shell.

Hamed Asadi - One of the best experts on this subject based on the ideXlab platform.

  • Computationally efficient model for flow-induced instability of CNT reinforced Functionally graded truncated conical curved panels subjected to axial compression
    Computer Methods in Applied Mechanics and Engineering, 2017
    Co-Authors: M Mehri, Hamed Asadi, M.a. Kouchakzadeh
    Abstract:

    Abstract As a first endeavor, the aeroelastic responses of Functionally graded carbon nanotube reinforced composite (FG-CNTRC) truncated conical curved panels subjected to aerodynamic load and axial compression are investigated. The nonlinear dynamic equations of FG-CNTRC conical curved panels are derived according to Green’s strains and the Novozhilov nonlinear shell theory. The aerodynamic load is estimated in accordance with the quasi-steady Krumhaar’s modified supersonic piston theory by taking into account the effect of the panel curvature. Matrix transform method along with the harmonic differential quadrature method (HDQM) are employed to solve the nonlinear equations of motion of the FG-CNTRC truncated conical curved panel. The advantage of the matrix transform method is that we only need to discretize the meridional direction. Effects of semi-vertex angle of the cone, subtended angle of the panel, boundary conditions, geometrical parameters, volume fraction and distribution of CNT, and Mach number on the aeroelastic characteristics of the FG-CNTRC conical curved panel are put into evidence via a set of parametric studies and pertinent conclusions are outlined. The results prove that the panels with different FG distributions have different critical dynamic pressure. It is found that the semi-vertex and subtended angles play a pivotal role in changing the critical circumferential mode number of the flutter instability. Besides, the research shows that the superb efficiency of proposed method with few grid points, which requires less CPU time, are attributed to the matrix transform method and the higher-order harmonic Approximation Function in the HDQM.

  • buckling and vibration analysis of a pressurized cnt reinforced Functionally graded truncated conical shell under an axial compression using hdq method
    Computer Methods in Applied Mechanics and Engineering, 2016
    Co-Authors: M Mehri, Hamed Asadi, Q Wang
    Abstract:

    Abstract The present research deals with bifurcation and vibration responses of a composite truncated conical shell with embedded single-walled carbon nanotubes (SWCNTs) subjected to an external pressure and axial compression simultaneously. The distribution of reinforcements through the thickness of the shell is assumed to be either uniform or Functionally graded. The equations of motion are established using Green–Lagrange type nonlinear kinematics within the framework of Novozhilov nonlinear shell theory. Linear membrane prebuckling analysis is conducted to extract the prebuckling deformations. The stability equations are derived by applying the adjacent equilibrium criterion to the prebuckling state of the conical shell. A semi-analytical solution on the basis of the trigonometric expansion through the circumferential direction along with the harmonic differential quadrature (HDQ) discretization in the meridional direction is developed. A series of comparison studies are carried out to assure the accuracy and the convergence of the HDQ method. The research indicates that the superb accuracy and efficiency of solutions with few grid points are attributed to the higher-order harmonic Approximation Function in the HDQ method. Parametric studies are also presented to investigate the influence of boundary conditions, semi-vertex angle of the cone, volume fraction and distribution of CNTs on stability and vibration characteristics of the truncated conical shell. The results show that both volume fraction and distribution of CNTs play a pivotal role in the natural frequencies, buckling mode and buckling loads of the FG-CNTRC truncated conical shell.

M.a. Kouchakzadeh - One of the best experts on this subject based on the ideXlab platform.

  • Computationally efficient model for flow-induced instability of CNT reinforced Functionally graded truncated conical curved panels subjected to axial compression
    Computer Methods in Applied Mechanics and Engineering, 2017
    Co-Authors: M Mehri, Hamed Asadi, M.a. Kouchakzadeh
    Abstract:

    Abstract As a first endeavor, the aeroelastic responses of Functionally graded carbon nanotube reinforced composite (FG-CNTRC) truncated conical curved panels subjected to aerodynamic load and axial compression are investigated. The nonlinear dynamic equations of FG-CNTRC conical curved panels are derived according to Green’s strains and the Novozhilov nonlinear shell theory. The aerodynamic load is estimated in accordance with the quasi-steady Krumhaar’s modified supersonic piston theory by taking into account the effect of the panel curvature. Matrix transform method along with the harmonic differential quadrature method (HDQM) are employed to solve the nonlinear equations of motion of the FG-CNTRC truncated conical curved panel. The advantage of the matrix transform method is that we only need to discretize the meridional direction. Effects of semi-vertex angle of the cone, subtended angle of the panel, boundary conditions, geometrical parameters, volume fraction and distribution of CNT, and Mach number on the aeroelastic characteristics of the FG-CNTRC conical curved panel are put into evidence via a set of parametric studies and pertinent conclusions are outlined. The results prove that the panels with different FG distributions have different critical dynamic pressure. It is found that the semi-vertex and subtended angles play a pivotal role in changing the critical circumferential mode number of the flutter instability. Besides, the research shows that the superb efficiency of proposed method with few grid points, which requires less CPU time, are attributed to the matrix transform method and the higher-order harmonic Approximation Function in the HDQM.

Cyriel M A Pennartz - One of the best experts on this subject based on the ideXlab platform.

  • estimation of the entropy on the basis of its polynomial representation
    International Symposium on Information Theory, 2012
    Co-Authors: Martin Vinck, Francesco P Battaglia, V B Balakirsky, A Han J Vinck, Cyriel M A Pennartz
    Abstract:

    An algorithm for estimating the entropy, which is based on the representation of the entropy Function as the sum of two polynomial terms, called the polynomial Approximation Function and the remainder, is proposed. We construct an accurate and unbiased estimate of the value of the polynomial Approximation Function and use the known Bayesian approach to estimate the remainder. The combined estimator essentially reduces the bias of the constructed estimate as compared to the known estimators. Simulation results that confirm the claim are presented.

  • estimation of the entropy based on its polynomial representation
    Physical Review E, 2012
    Co-Authors: Martin Vinck, Francesco P Battaglia, V B Balakirsky, A J H Vinck, Cyriel M A Pennartz
    Abstract:

    Estimating entropy from empirical samples of finite size is of central importance for information theory as well as the analysis of complex statistical systems. Yet, this delicate task is marred by intrinsic statistical bias. Here we decompose the entropy Function into a polynomial Approximation Function and a remainder Function. The Approximation Function is based on a Taylor expansion of the logarithm. Given n observations, we give an unbiased, linear estimate of the first n power series terms based on counting sets of k coincidences. For the remainder Function we use nonlinear Bayesian estimation with a nearly flat prior distribution on the entropy that was developed by Nemenman, Shafee, and Bialek. Our simulations show that the combined entropy estimator has reduced bias in comparison to other available estimators.