The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform

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.

Y Kiani - One of the best experts on this subject based on the ideXlab platform.

  • buckling of functionally graded graphene reinforced conical shells under external pressure in thermal environment
    Composites Part B-engineering, 2019
    Co-Authors: Y Kiani
    Abstract:

    Abstract In the present research, buckling analysis of composite laminated conical shells reinforced with graphene sheets is investigated. Graphene sheets as reinforcements are distributed in each lamina. Volume fraction of graphene in each layer may be different which results in a piecewise functionally graded conical shell. First order shear deformation shell theory, Donnell kinematic assumptions and von Karman type of geometrical non-linearity are used to establish the governing equations of the conical shell and the associated boundary conditions. The pre-buckling forces of the shell are obtained employing a membrane analysis. The linear stability equations are developed using the adjacent Equilibrium Criterion. These equations are discreted by means of the generalised differential quadratures across the shell length and Fourier expansion through the circumferential direction. An eigenvalue problem is obtained which yields the critical buckling pressure of the conical shell in thermal environment and the circumferential mode number at the onset of buckling. Comparison studies are provided for graphene reinforced and conventional composite laminated cylindrical shells and also isotropic conical shells with and without thermal environment. Afterwards parametric studies are given for buckling of functionally graded graphene reinforced composite laminated conical shells in thermal environment with different boundary conditions. It is shown that, temperature elevation decreases the critical buckling pressures of the conical shell significantly. Also buckling pressure of the shell may be enhanced through a piecewise functionally graded distribution of volume fraction of reinforcements.

  • enhanced thermal buckling of laminated composite cylindrical shells with shape memory alloy
    Journal of Composite Materials, 2016
    Co-Authors: Hamed Asadi, Y Kiani, M M Aghdam, M Shakeri
    Abstract:

    Thermal bifurcation behavior of cross-ply laminated composite cylindrical shells embedded with shape memory alloy fibers is investigated. Properties of the constituents are assumed to be temperature-dependent. Donnell's kinematic assumptions accompanied with the von-Karman type of geometrical non-linearity are used to derive the governing equations of the shell. Furthermore, the one-dimensional constitutive law of Brinson is used to predict the behavior of shape memory alloy fibers through the heating process. Governing Equilibrium equations are established by employing the static version of virtual displacements principle. Linear membrane pre-buckling analysis is performed to extract the pre-buckling deformations of the shell. Applying the well-known adjacent Equilibrium Criterion to the pre-buckling state of the shell, stability equations are derived. The governing equations are solved via a semi-analytical solution employing the exact trigonometric function in circumferential direction and the harmonic...

Donald Mackay - One of the best experts on this subject based on the ideXlab platform.

  • uncertainty analysis using a fugacity based multimedia mass balance model application of the updated eqc model to decamethylcyclopentasiloxane d5
    Chemosphere, 2013
    Co-Authors: David E Powell, Lauren Hughes, Donald Mackay
    Abstract:

    Abstract The Equilibrium Criterion (EQC) model developed and published in 1996 was recently revised to include improved treatment of input partitioning and reactivity data, temperature dependence and an easier sensitivity and uncertainty analysis. This New EQC model was used to evaluate the multimedia, fugacity-based fate of decamethylcyclopentasiloxane (D5; CAS No. 541-02-6) in the environment over a temperature range of 1–25 °C. In addition, Monte Carlo uncertainty analysis was used to quantitatively determine the influence of temperature and input partitioning and reactivity data on the behavior of D5 under various emission scenarios. Results indicated that emission mode was the most influential factor determining the fate and distribution of D5 in the model environment. When emitted to air and soil, D5 partitioned to and remained in the air compartment where rates of removal from degradation and advection processes were relatively rapid. In contrast, D5 emitted to water resulted in a substantial mass fraction of D5 being accumulated in the sediment compartment, where rates of removal from degradation and advection processes were slow. The mass distributions and fate of D5 in the model environment were strongly influenced by multiple input parameters, including temperature, the mode of emission (especially emission rate to water), K OC and half-life in air. As temperature decreased from 25 °C to 1 °C, K OC and half-life in air became increasingly more influential such that the mass distribution of D5 increased in air and decreased in sediment, resulting in decreased overall persistence.

  • assessment of chemical fate in the environment using evaluative regional and local scale models illustrative application to chlorobenzene and linear alkylbenzene sulfonates
    Environmental Toxicology and Chemistry, 1996
    Co-Authors: Donald Mackay, Antonio Di Guardo, Sally Paterson, Gabriel Kicsi, Christina E Cowan, David M Kane
    Abstract:

    Evaluation of chemical fate in the environment has been suggested to be best accomplished using a five-stage process in which a sequence of increasing site-specific multimedia mass balance models is applied. This approach is illustrated for chlorobenzene and linear alkylbenzene sulfonates (LAS). The first two stages involve classifying the chemical and quantifying the emissions into each environmental compartment. In the third stage, the characteristics of the chemical are determined using the evaluative Equilibrium Criterion model, which is capable of treating a variety of chemicals including those that are involatile and insoluble in water. This evaluation is conducted in three steps using levels I, II, and III versions of the model, which introduce increasing complexity and more realistic representations of the environment. In the fourth stage, ChemCAN, which is a level III model for specific regions of Canada, is used to predict the chemical's fate in southern Ontario. The final stage is to apply local environmental models to predict environmental exposure concentrations. For chlorobenzene, the local model was the SoilFug model, which predicts the fate of agro-chemicals, and for LAS the WW-TREAT, GRiDS, and ROUT models were used to predict the fate of LAS in a sewage treatment plant and in riverine receiving waters. It is concluded that this systematic approach provides a comprehensive assessment of chemical fate, revealing the broad characteristics of chemical behavior and quantifying the likely local and regional exposure levels.

Hamed Asadi - 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.

  • enhanced thermal buckling of laminated composite cylindrical shells with shape memory alloy
    Journal of Composite Materials, 2016
    Co-Authors: Hamed Asadi, Y Kiani, M M Aghdam, M Shakeri
    Abstract:

    Thermal bifurcation behavior of cross-ply laminated composite cylindrical shells embedded with shape memory alloy fibers is investigated. Properties of the constituents are assumed to be temperature-dependent. Donnell's kinematic assumptions accompanied with the von-Karman type of geometrical non-linearity are used to derive the governing equations of the shell. Furthermore, the one-dimensional constitutive law of Brinson is used to predict the behavior of shape memory alloy fibers through the heating process. Governing Equilibrium equations are established by employing the static version of virtual displacements principle. Linear membrane pre-buckling analysis is performed to extract the pre-buckling deformations of the shell. Applying the well-known adjacent Equilibrium Criterion to the pre-buckling state of the shell, stability equations are derived. The governing equations are solved via a semi-analytical solution employing the exact trigonometric function in circumferential direction and the harmonic...

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

  • on the buckling of functionally graded cylindrical shells under combined external pressure and axial compression
    Journal of Pressure Vessel Technology-transactions of The Asme, 2010
    Co-Authors: P Khazaeinejad, Mohammad Mahdi Najafizadeh, J Jenabi, M R Isvandzibaei
    Abstract:

    The stability problem of a circular cylindrical shell composed of functionally graded materials with elasticity modulus varying continuously in the thickness direction under combined external pressure and axial compression loads is studied in this paper. The formulation is based on the first-order shear deformation theory. A load interaction parameter is defined to express the combination of applied axial compression and external pressure. The stability equations are derived by the adjacent Equilibrium Criterion method. These equations are employed to analyze the buckling behavior and obtain the critical buckling loads. A detailed numerical study is carried out to bring out the effects of the power law index of functionally graded material, load interaction parameter, thickness ratio, and aspect ratio on the critical buckling loads. The validity of the present analysis was checked by comparing the present results with those results available in literature.

  • on the buckling of functionally graded cylindrical shells under combined external pressure and axial compression
    ASME 2009 Pressure Vessels and Piping Conference, 2009
    Co-Authors: P Khazaeinejad, Mohammad Mahdi Najafizadeh, J Jenabi, M R Isvandzibaei
    Abstract:

    The stability problem of a circular cylindrical shell composed of functionally graded materials with Young’s modulus varying continuously in the thickness direction under combined lateral pressure and axial compression loads is studied in this paper. The formulation is based on the first order shear deformation theory. A load interaction parameter is defined to express the combination of applied axial compression and external pressure. The stability equations are derived by the adjacent Equilibrium Criterion method. These equations are employed to analyze the buckling behavior and obtain the critical buckling loads. A detailed numerical study is carried out to bring out the effects of the power law index of functionally graded material, load interaction parameter, thickness ratio, and aspect ratio on the critical buckling loads. Validity of the present analysis was checked by comparing the results with those are available in the literature.© 2009 ASME