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Hui-shen Shen - One of the best experts on this subject based on the ideXlab platform.

  • Nonlinear vibration of FGM doubly curved panels resting on elastic foundations in thermal environments
    Aerospace Science and Technology, 2015
    Co-Authors: Hui-shen Shen, Xiuhua Chen, Linzhi Wu, Xiao-lin Huang
    Abstract:

    Abstract A large amplitude vibration analysis is presented for a shear deformable doubly curved panel made of functionally graded materials (FGMs) resting on elastic foundations in thermal environments. The effective material properties are evaluated using the Mori–Tanaka micromechanics Model. The formulations are based on a higher order shear deformation theory and von Karman strain–displacement relationships. The panel–foundation interaction and thermal effects are also included. The temperature-dependent material properties of FGMs are assumed to be graded in the thickness direction according to a simple power law distribution. The motion equations are solved by a two-step perturbation approach to determine the nonlinear frequencies of the FGM doubly curved panel. The numerical illustrations cover small- and large-amplitude vibration characteristics of FGM doubly curved panels resting on elastic foundations of Pasternak-type. The results obtained from the Mori–Tanaka Model are compared with those obtained from the Voigt Model. The results confirm that in most cases Voigt Model and Mori–Tanaka Model have the same accuracy for predicting the vibration characteristics of FGM doubly curved panels. The effects of volume fraction index, temperature variation, foundation stiffness and panel curvature ratio on the nonlinear free vibration behaviors of FGM doubly curved panels are also discussed in detail.

  • postbuckling of fgm cylindrical panels resting on elastic foundations subjected to axial compression under heat conduction
    Journal of Aerospace Engineering, 2015
    Co-Authors: Hui-shen Shen, Hai Wang
    Abstract:

    AbstractA postbuckling analysis is presented for functionally graded material (FGM) cylindrical panels resting on elastic foundations subjected to axial compression under heat conduction. Two kinds of micromechanics Models, namely, Voigt Model and Mori-Tanaka Model, are considered. The material properties of FGMs are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents and are assumed to be temperature-dependent. The formulations are based on a higher-order shear deformation theory with a von Karman-type of kinematic nonlinearity. The panel-foundation interaction and thermal effects are also included. The nonlinear prebuckling deformations and initial geometric imperfections of the panel are both taken into account. A singular perturbation technique along with a two-step perturbation approach is employed to determine the buckling loads and postbuckling equilibrium paths. The effects of volume fraction index, tempe...

  • Nonlinear vibration of shear deformable FGM cylindrical panels resting on elastic foundations in thermal environments
    Composites Part B-engineering, 2014
    Co-Authors: Hui-shen Shen, Hai Wang
    Abstract:

    Abstract This paper investigates the large amplitude vibration behavior of a shear deformable FGM cylindrical panel resting on elastic foundations in thermal environments. Two kinds of micromechanics Models, namely, Voigt Model and Mori–Tanaka Model, are considered. The motion equations are based on a higher order shear deformation shell theory that includes shell panel-foundation interaction. The thermal effects are also included and the material properties of FGMs are assumed to be temperature-dependent. The equations of motion are solved by a two step perturbation technique to determine the nonlinear frequencies of the FGM cylindrical panel. Detailed parametric studies are carried out to investigate effects of volume fraction index, temperature variation, panel curvature ratio, foundation stiffness and in-plane boundary conditions on nonlinear vibration behaviors of FGM cylindrical panels. The results confirm that in most cases Voigt Model and Mori–Tanaka Model have the same accuracy for predicting the vibration characteristics of FGM cylindrical panels.

  • Nonlinear analysis of shear deformable FGM beams resting on elastic foundations in thermal environments
    International Journal of Mechanical Sciences, 2014
    Co-Authors: Hui-shen Shen, Zhen-xin Wang
    Abstract:

    Abstract This paper deals with the large amplitude vibration, nonlinear bending and thermal postbuckling of functionally graded material (FGM) beams resting on an elastic foundation in thermal environments. Two kinds of micromechanics Models, namely, Voigt Model and Mori-Tanaka Model, are considered. The motion equations are based on a higher order shear deformation beam theory that includes beam–foundation interaction. The thermal effects are also included and the material properties of FGMs are assumed to be temperature-dependent. The numerical illustrations concern the nonlinear vibration, nonlinear bending and thermal postbuckling of FGM beams resting on Pasternak elastic foundations under different thermal environmental conditions. It is found that the FGM beam with intermediate material properties does not necessarily have intermediate nonlinear frequencies. The thermal postbuckling path of simply supported FGM beams is no longer of the bifurcation type for both uniform and non-uniform temperature fields.

  • Thermal Postbuckling of Shear Deformable FGM Cylindrical Shells Surrounded by an Elastic Medium
    Journal of Engineering Mechanics-asce, 2013
    Co-Authors: Hui-shen Shen
    Abstract:

    AbstractThis paper presents a study on the thermal postbuckling response of a shear deformable functionally graded cylindrical shell of finite length embedded in a large outer elastic medium. The surrounding elastic medium is Modeled as a Pasternak foundation. Two kinds of micromechanics Models, namely the Voigt Model and Mori-Tanaka Model, are considered. The governing equations are based on a higher-order shear deformation shell theory that includes shell-foundation interaction. The thermal effects are also included and the material properties of functionally graded materials (FGMs) are assumed to be temperature dependent. The governing equations are solved by a singular perturbation technique. The numerical results show that in some cases the FGM cylindrical shell with intermediate volume fraction index does not have intermediate buckling temperature and thermal postbuckling strength. The results reveal that Voigt Model and Mori-Tanaka Model have the same accuracy for predicting the thermal buckling an...

A Chakraborty - One of the best experts on this subject based on the ideXlab platform.

  • A stochastic micromechanical Model for elastic properties of functionally graded materials
    Mechanics of Materials, 2007
    Co-Authors: S Rahman, A Chakraborty
    Abstract:

    A stochastic micromechanical Model is presented for predicting probabilistic characteristics of elastic mechanical properties of an isotropic functionally graded material (FGM) subject to statistical uncertainties in material properties of constituents and their respective volume fractions. The Model involves non-homogeneous, non-Gaussian random field representation of phase volume fractions and random variable description of constituent material properties, a three-phase Mori–Tanaka Model for underlying micromechanics and homogenization, and a novel dimensional decomposition method for obtaining probabilistic descriptors of effective FGM properties. Four numerical examples involving statistical properties of input random fields, limited experimental validation, and the second-moment characteristics and probability density functions of effective mechanical properties of FGM illustrate the proposed stochastic Model. The results indicate that the Model provides both accurate and computationally efficient estimates of probabilistic characteristics of effective FGM properties.

  • A stochastic micromechanical Model for elastic properties of functionally graded materials
    Mechanics of Materials, 2007
    Co-Authors: S Rahman, A Chakraborty
    Abstract:

    A stochastic micromechanical Model is presented for predicting probabilistic characteristics of elastic mechanical properties of an isotropic functionally graded material (FGM) subject to statistical uncertainties in material properties of constituents and their respective volume fractions. The Model involves non-homogeneous, non-Gaussian random field representation of phase volume fractions and random variable description of constituent material properties, a three-phase Mori-Tanaka Model for underlying micromechanics and homogenization, and a novel dimensional decomposition method for obtaining probabilistic descriptors of effective FGM properties. Four numerical examples involving statistical properties of input random fields, limited experimental validation, and the second-moment characteristics and probability density functions of effective mechanical properties of FGM illustrate the proposed stochastic Model. The results indicate that the Model provides both accurate and computationally efficient estimates of probabilistic characteristics of effective FGM properties. © 2006 Elsevier Ltd. All rights reserved.

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

  • A micromechanical approach for semi-analytical low-velocity impact analysis of a bidirectional functionally graded circular plate resting on an elastic foundation
    Meccanica, 2013
    Co-Authors: M. Shariyat, R. Jafari
    Abstract:

    All the rare investigations made on low velocity impact analysis of the functionally graded plates have employed the simple rule of mixture that may lead to inconsistent results in some circumstances, e.g., when the Poisson ratios of the constituent materials are quite different. On the other hand, these researches have been performed either by purely using a commercial finite element software or employing the conventional Hertz-type contact laws that are valid only if the overall plate flexibility is ignored. In the present paper, it is mainly focused on four novelties: (i) description of the apparent stiffness of the contact region of the plate based on the micromechanical Mori-Tanaka Model for two-directional variations of the material properties of the functionally graded plates, (ii) employing an enhanced contact Model, considering the micromechanics-based material Model and plate and foundation compliances, (iii) evaluation effects of the foundation stiffness on the apparent impact stiffness and the plate responses, and (iv) using a weighted residual semi-analytical solution procedure and an iterative updating scheme to solve the nonlinear governing equations. Presence of the elastic foundation has caused very interesting, unexpected but reasonable behaviors to be observed.

S Rahman - One of the best experts on this subject based on the ideXlab platform.

  • A stochastic micromechanical Model for elastic properties of functionally graded materials
    Mechanics of Materials, 2007
    Co-Authors: S Rahman, A Chakraborty
    Abstract:

    A stochastic micromechanical Model is presented for predicting probabilistic characteristics of elastic mechanical properties of an isotropic functionally graded material (FGM) subject to statistical uncertainties in material properties of constituents and their respective volume fractions. The Model involves non-homogeneous, non-Gaussian random field representation of phase volume fractions and random variable description of constituent material properties, a three-phase Mori–Tanaka Model for underlying micromechanics and homogenization, and a novel dimensional decomposition method for obtaining probabilistic descriptors of effective FGM properties. Four numerical examples involving statistical properties of input random fields, limited experimental validation, and the second-moment characteristics and probability density functions of effective mechanical properties of FGM illustrate the proposed stochastic Model. The results indicate that the Model provides both accurate and computationally efficient estimates of probabilistic characteristics of effective FGM properties.

  • A stochastic micromechanical Model for elastic properties of functionally graded materials
    Mechanics of Materials, 2007
    Co-Authors: S Rahman, A Chakraborty
    Abstract:

    A stochastic micromechanical Model is presented for predicting probabilistic characteristics of elastic mechanical properties of an isotropic functionally graded material (FGM) subject to statistical uncertainties in material properties of constituents and their respective volume fractions. The Model involves non-homogeneous, non-Gaussian random field representation of phase volume fractions and random variable description of constituent material properties, a three-phase Mori-Tanaka Model for underlying micromechanics and homogenization, and a novel dimensional decomposition method for obtaining probabilistic descriptors of effective FGM properties. Four numerical examples involving statistical properties of input random fields, limited experimental validation, and the second-moment characteristics and probability density functions of effective mechanical properties of FGM illustrate the proposed stochastic Model. The results indicate that the Model provides both accurate and computationally efficient estimates of probabilistic characteristics of effective FGM properties. © 2006 Elsevier Ltd. All rights reserved.

Christian N. Della - One of the best experts on this subject based on the ideXlab platform.

  • Micromechanics Model for predicting effective elastic moduli of porous ceramic matrices with randomly oriented carbon nanotube reinforcements
    AIP Advances, 2015
    Co-Authors: Christian N. Della, Shengjie Ying, Yun Li
    Abstract:

    Multi-step micromechanics-based Models are developed to predict the overall effective elastic moduli of porous ceramic with randomly oriented carbon nanotube (CNT) reinforcements. The presence of porosity in the ceramic matrix that has been previously neglected in the literature is considered in present analysis. The ceramic matrix with porosity is first homogenized using a classical Mori-Tanaka Model. Then, the homogenized porous ceramic matrix with randomly oriented CNTs is analysed using two micromechanics Models. The results predicted by the present Models are compared with experimental and analytical results that have been reported in literature. The comparison shows that the discrepancies between the present analytical results and experimental data are about 10% for 4 wt% of CNTs and about 0.5% for 8 wt% CNTs, both substantially lower than the discrepancies currently reported in the literature.

  • Effective Electromechanical Properties and Performances of 1-3 Piezoelectric Composites with a Porous Matrix
    2015
    Co-Authors: Christian N. Della
    Abstract:

    Piezoelectric composites with 1-3 connectivity have been widely studied due to their practical applications to biomedical imaging, ultrasound therapy and bone tissue engineering. They are flexible to conform to curved surfaces and their electromechanical properties and performance can be tailored for specific applications. In this research work, a multi-step micromechanics based Mori-Tanaka Model for piezoelectric composite is developed to study the effective performances of 1-3 piezoelectric composites with piezoceramic fibers embedded in porous piezoelectric and non-piezoelectric matrices. The porous matrix is first homogenized using the Mori-Tanaka Model, and then the porous matrix with piezoelectric fibers is homogenized using the Mori-Tanaka method for piezoelectric. The present work focuses on the performances of composites using various types of piezoelectric and non-piezoelectric materials for bone tissue engineering applications. Results of the studies show that the piezoelectric composite performances are largely dependent on the fiber volume fraction and that the presence of porosity further improved the performance of the composites.

  • Mechanical Properties of Carbon Nanotubes Reinforced Ultra High Molecular Weight Polyethylene
    Solid State Phenomena, 2009
    Co-Authors: Christian N. Della, Dong Wei Shu
    Abstract:

    Carbon nanotubes (CNT) have been shown to enhance the engineering properties of plastic fibers in ballistic-resistant garments enabling the garments to withstand very high impact forces while remaining to be lightweight. Previous study shows that by reinforcing ultra high molecular weight polyethylene (UHMWPE) fibers with a small amount of carbon nanotubes, the fibers are simultaneously toughened and strengthened. In this paper, we study the mechanical properties of carbon nanotube reinforced ultra high molecular weight polyethylene (UHMWPE) by using micromechanics-based Mori-Tanaka Model. Results show that the addition of small amount of carbon nanotubes as reinforcement can substantially improve the mechanical properties of the UHMWPE fibers.

  • A Comparative Study of the Hydrostatic Performances of 1-3 Piezoelectric Composites with a Porous Matrix
    Advanced Materials Research, 2008
    Co-Authors: Christian N. Della
    Abstract:

    In this research, a comparative study of the hydrostatic performances of 1-3 piezoelectric composites with a porous matrix is presented. The piezoelectric fibers PZT-5H and PZT-7A are considered in the present study. The micromechanics based Mori-Tanaka Model is used. Results of the study show that PZT-5H/Aradite D composite have better hydrostatic performance than PZT- 7A/Aradite D composite, and this advantage of PZT-5H/Aradite D composite over PZT-7A/Aradite D composite increases with the increase of porosity in the matrix.

  • On the performance of 1–3 piezoelectric composites with a passive and active matrix
    Sensors and Actuators A-physical, 2007
    Co-Authors: Christian N. Della
    Abstract:

    Piezoelectric composites with 1–3 connectivity are an important class of materials for underwater acoustics and biomedical imaging. Their dependence on the electromechanical properties and geometry of the piezoelectric fibers creates an opportunity for tailoring its performance according to the design requirements. In this research, the performance of 1–3 piezoelectric composite with an active and passive matrix is studied. The micromechanics based Mori-Tanaka Model for piezoelectric composite is used to determine the electromechanical moduli of the composites. In comparison with a passive polymer matrix, the use of active polymer matrix can significantly enhance the hydrostatic performance of the piezoelectric composite. However, no significant improvement on the electromechanical coupling and acoustic impedance is observed. Further results reveal that the use of piezoelectric ceramic matrix does not improve the performance of the composite.