The Experts below are selected from a list of 5646 Experts worldwide ranked by ideXlab platform

Xue Fu - One of the best experts on this subject based on the ideXlab platform.

  • a Micromechanics Model for turgor pressure of arabidopsis thaliana protoplast
    2014
    Co-Authors: Bochu Wang, Xingyan Yang, Yichuan Wang, Xue Fu
    Abstract:

    Understanding the key role of turgor pressure in plant growth and development is important for recognizing the mechanical behavior of plant cell wall material deposition. In this study, we developed a Micromechanics Model to demonstrate how uniaxial strain influences turgor pressure of isolated Arabidopsis thaliana protoplasts, and their deformation and morphogenesis. In this Model, the protoplast is treated as an elastic inclusion in a surrounding agarose gel, allowing the turgor pressure in response to the 20 % uniaxial strain exerted on the protoplast–agarose gel composite material system. Based on the Eshelby method and the Mori–Tanaka’s theory (Eshelby in Proc R Soc Lond A 241(1226):376–396, 1957; Mori and Tanaka in Acta Metall 21(5):571–574, 1973), turgor pressure can be taken into account as a uniform strain acting on protoplasts. By using this Model, the relationship between the plant cell morphology changes, and their effective properties are derived with a theoretical basis.

  • a Micromechanics Model for turgor pressure of arabidopsis thaliana protoplast
    2014
    Co-Authors: Bochu Wang, Xingyan Yang, Yichuan Wang, Xue Fu
    Abstract:

    Understanding the key role of turgor pressure in plant growth and development is important for recognizing the mechanical behavior of plant cell wall material deposition. In this study, we developed a Micromechanics Model to demonstrate how uniaxial strain influences turgor pressure of isolated Arabidopsis thaliana protoplasts, and their deformation and morphogenesis. In this Model, the protoplast is treated as an elastic inclusion in a surrounding agarose gel, allowing the turgor pressure in response to the 20 % uniaxial strain exerted on the protoplast–agarose gel composite material system. Based on the Eshelby method and the Mori–Tanaka’s theory (Eshelby in Proc R Soc Lond A 241(1226):376–396, 1957; Mori and Tanaka in Acta Metall 21(5):571–574, 1973), turgor pressure can be taken into account as a uniform strain acting on protoplasts. By using this Model, the relationship between the plant cell morphology changes, and their effective properties are derived with a theoretical basis.

Gunther Meschke - One of the best experts on this subject based on the ideXlab platform.

  • expansion and deterioration of concrete due to asr micromechanical Modeling and analysis
    2019
    Co-Authors: Tagir Iskhakov, Jithender J. Timothy, Gunther Meschke
    Abstract:

    Abstract A multi-scale Micromechanics Model is proposed to describe the expansion and deterioration of concrete due to Alkali-Silica Reaction (ASR). The mechanics of ASR induced deterioration of a Representative Elementary Volume (REV) of concrete is Modeled through a synthesis of distributed microcracking and mean-field homogenization. At the microscale, ASR-gel-pressure induced microcrack growth in and around the reactive aggregates is Modeled using the framework of linear elastic fracture mechanics. Mean-field homogenization across multiple scales is used to obtain the overall expansion and degradation of the material. By specifying the spatial distribution of the pressurizing gel, two different ASR mechanisms associated with “slowly” and “rapidly” reactive aggregates can be Modeled. Experimental data for concrete degradation as a function of the macroscopic expansion is found to lie within the theoretical upper and lower bounds that characterize the distribution of the gel in the aggregate or the cement paste.

  • Effective Diffusivity of Porous Materials with Microcracks: Self-Similar Mean-Field Homogenization and Pixel Finite Element Simulations
    2018
    Co-Authors: Jithender J. Timothy, Gunther Meschke
    Abstract:

    We investigate the influence of distributed microcracks on the overall diffusion properties of a porous material using the self-similar cascade continuum Micromechanics Model within the framework of mean-field homogenization and computational homogenization of diffusion simulations using a high-resolution pixel finite element method. In addition to isotropic, also anisotropic crack distributions are considered. The comparison of the results from the cascade continuum Micromechanics Model and the numerical simulations provides a deeper insight into the qualitative transport characteristics such as the influence of the crack density on the complexity and connectivity of crack networks. The analysis shows that the effective diffusivity for a disordered microcrack distribution is independent of the absolute length scale of the cracks. It is observed that the overall effective diffusivity of a microcracked material with the microcracks oriented in the direction of transport is not necessarily higher than that of a material with a random orientation of microcracks, independent of the microcrack density.

  • cascade continuum Micromechanics Model for the effective permeability of solids with distributed microcracks self similar mean field homogenization and image analysis
    2017
    Co-Authors: Jithender J. Timothy, Gunther Meschke
    Abstract:

    Abstract The transport and fluid flow in heterogeneous materials such as rocks, ceramics and concrete with a distributed random microcrack network is strongly influenced by the density and the topology (distribution and connectivity) of microcracks. The overall fluid flow characteristics of such microcracked solids can be quantified in terms of an effective permeability. In the paper, a semi-analytical formulation for the effective permeability is proposed within the framework of the mean-field homogenization method using the cascade continuum Micromechanics Model considering long range and short range interactions. We compare Model predictions of the percolation threshold i.e. critical volume fraction of microcracks beyond which a solid with distributed microcracks becomes permeable, using results from numerical simulations. The Model reveals a new perspective into the self-similar characteristics of the microcrack morphology near the threshold volume fraction of microcracks at which the microcrack structure changes from multiple disconnected microcracks to a connected self-similar microcracked structure.

  • a cascade continuum Micromechanics Model for the effective elastic properties of porous materials
    2016
    Co-Authors: Jithender J. Timothy, Gunther Meschke
    Abstract:

    Abstract The elastic properties of porous materials with a disordered pore structure are estimated using the mean-field Eshelby homogenization scheme together with the principle of recurrence to generate a cascade of effective microstructures as a function of the porosity and the cascade level n . Starting with the Hashin–Shtrikman upper bound for porous materials, the proposed cascade Micromechanics Model generates a hierarchy of micro-structures which evolve from an initial configuration of a porous material with spherical pores embedded within an elastic solid phase consistent with the Mori–Tanaka matrix inclusion morphology to a porous material characterized by a hierarchic distribution of spherical elastic grains. The Model is explicit and allows for an easy computational implementation. It predicts physically consistent threshold porosities, characteristic for the specific morphology of the porous material under consideration, beyond which the material loses its stiffness. The validity of the cascade Micromechanics Model is evaluated against experimental data for various materials ranging from foam to ceramics with different pore structures.

  • Cascade Lattice Micromechanics Model for the Effective Permeability of Materials with Microcracks
    2016
    Co-Authors: Jithender J. Timothy, Gunther Meschke
    Abstract:

    AbstractWithin the framework of mean-field homogenization methods, a lattice version of the cascade Micromechanics Model for the estimation of the effective permeability of microcracked materials w...

Jithender J. Timothy - One of the best experts on this subject based on the ideXlab platform.

  • expansion and deterioration of concrete due to asr micromechanical Modeling and analysis
    2019
    Co-Authors: Tagir Iskhakov, Jithender J. Timothy, Gunther Meschke
    Abstract:

    Abstract A multi-scale Micromechanics Model is proposed to describe the expansion and deterioration of concrete due to Alkali-Silica Reaction (ASR). The mechanics of ASR induced deterioration of a Representative Elementary Volume (REV) of concrete is Modeled through a synthesis of distributed microcracking and mean-field homogenization. At the microscale, ASR-gel-pressure induced microcrack growth in and around the reactive aggregates is Modeled using the framework of linear elastic fracture mechanics. Mean-field homogenization across multiple scales is used to obtain the overall expansion and degradation of the material. By specifying the spatial distribution of the pressurizing gel, two different ASR mechanisms associated with “slowly” and “rapidly” reactive aggregates can be Modeled. Experimental data for concrete degradation as a function of the macroscopic expansion is found to lie within the theoretical upper and lower bounds that characterize the distribution of the gel in the aggregate or the cement paste.

  • Effective Diffusivity of Porous Materials with Microcracks: Self-Similar Mean-Field Homogenization and Pixel Finite Element Simulations
    2018
    Co-Authors: Jithender J. Timothy, Gunther Meschke
    Abstract:

    We investigate the influence of distributed microcracks on the overall diffusion properties of a porous material using the self-similar cascade continuum Micromechanics Model within the framework of mean-field homogenization and computational homogenization of diffusion simulations using a high-resolution pixel finite element method. In addition to isotropic, also anisotropic crack distributions are considered. The comparison of the results from the cascade continuum Micromechanics Model and the numerical simulations provides a deeper insight into the qualitative transport characteristics such as the influence of the crack density on the complexity and connectivity of crack networks. The analysis shows that the effective diffusivity for a disordered microcrack distribution is independent of the absolute length scale of the cracks. It is observed that the overall effective diffusivity of a microcracked material with the microcracks oriented in the direction of transport is not necessarily higher than that of a material with a random orientation of microcracks, independent of the microcrack density.

  • cascade continuum Micromechanics Model for the effective permeability of solids with distributed microcracks self similar mean field homogenization and image analysis
    2017
    Co-Authors: Jithender J. Timothy, Gunther Meschke
    Abstract:

    Abstract The transport and fluid flow in heterogeneous materials such as rocks, ceramics and concrete with a distributed random microcrack network is strongly influenced by the density and the topology (distribution and connectivity) of microcracks. The overall fluid flow characteristics of such microcracked solids can be quantified in terms of an effective permeability. In the paper, a semi-analytical formulation for the effective permeability is proposed within the framework of the mean-field homogenization method using the cascade continuum Micromechanics Model considering long range and short range interactions. We compare Model predictions of the percolation threshold i.e. critical volume fraction of microcracks beyond which a solid with distributed microcracks becomes permeable, using results from numerical simulations. The Model reveals a new perspective into the self-similar characteristics of the microcrack morphology near the threshold volume fraction of microcracks at which the microcrack structure changes from multiple disconnected microcracks to a connected self-similar microcracked structure.

  • a cascade continuum Micromechanics Model for the effective elastic properties of porous materials
    2016
    Co-Authors: Jithender J. Timothy, Gunther Meschke
    Abstract:

    Abstract The elastic properties of porous materials with a disordered pore structure are estimated using the mean-field Eshelby homogenization scheme together with the principle of recurrence to generate a cascade of effective microstructures as a function of the porosity and the cascade level n . Starting with the Hashin–Shtrikman upper bound for porous materials, the proposed cascade Micromechanics Model generates a hierarchy of micro-structures which evolve from an initial configuration of a porous material with spherical pores embedded within an elastic solid phase consistent with the Mori–Tanaka matrix inclusion morphology to a porous material characterized by a hierarchic distribution of spherical elastic grains. The Model is explicit and allows for an easy computational implementation. It predicts physically consistent threshold porosities, characteristic for the specific morphology of the porous material under consideration, beyond which the material loses its stiffness. The validity of the cascade Micromechanics Model is evaluated against experimental data for various materials ranging from foam to ceramics with different pore structures.

  • Cascade Lattice Micromechanics Model for the Effective Permeability of Materials with Microcracks
    2016
    Co-Authors: Jithender J. Timothy, Gunther Meschke
    Abstract:

    AbstractWithin the framework of mean-field homogenization methods, a lattice version of the cascade Micromechanics Model for the estimation of the effective permeability of microcracked materials w...

Tian Tang - One of the best experts on this subject based on the ideXlab platform.

  • a variational asymptotic Micromechanics Model for predicting thermoelastic properties of heterogeneous materials
    2007
    Co-Authors: Tian Tang
    Abstract:

    A variational asymptotic Micromechanics Model has been developed for predicting effective thermoelastic properties of composite materials, and recover the local fields within the unit cell. This theory adopts essential assumptions within the concept of Micromechanics, achieves an excellent accuracy, and provides a unified treatment for 1D, 2D, and 3D unit cells. This theory is implemented using the finite element method into the computer program, VAMUCH, a general-purpose Micromechanics analysis code. Several examples are used to validate the theory and the code. The results are compared with those available in the literature and those produced by a commercial finite element package.

  • variational asymptotic method for unit cell homogenization of periodically heterogeneous materials
    2007
    Co-Authors: Wenbin Yu, Tian Tang
    Abstract:

    A new Micromechanics Model, namely, the variational asymptotic method for unit cell homogenization (VAMUCH), is developed to predict the effective properties of periodically heterogeneous materials and recover the local fields. Considering the periodicity as a small parameter, we can formulate a variational statement of the unit cell through an asymptotic expansion of the energy functional. It is shown that the governing differential equations and periodic boundary conditions of mathematical homogenization theories (MHT) can be reproduced from this variational statement. In comparison to other approaches, VAMUCH does not rely on ad hoc assumptions, has the same rigor as MHT, has a straightforward numerical implementation, and can calculate the complete set of properties simultaneously without using multiple loadings. This theory is implemented using the finite element method and an engineering program, VAMUCH, is developed for micromechanical analysis of unit cells. Many examples of binary composites, fiber reinforced composites, and particle reinforced composites are used to demonstrate the application, power, and accuracy of the theory and the code of VAMUCH.

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

  • a Micromechanics Model for turgor pressure of arabidopsis thaliana protoplast
    2014
    Co-Authors: Bochu Wang, Xingyan Yang, Yichuan Wang, Xue Fu
    Abstract:

    Understanding the key role of turgor pressure in plant growth and development is important for recognizing the mechanical behavior of plant cell wall material deposition. In this study, we developed a Micromechanics Model to demonstrate how uniaxial strain influences turgor pressure of isolated Arabidopsis thaliana protoplasts, and their deformation and morphogenesis. In this Model, the protoplast is treated as an elastic inclusion in a surrounding agarose gel, allowing the turgor pressure in response to the 20 % uniaxial strain exerted on the protoplast–agarose gel composite material system. Based on the Eshelby method and the Mori–Tanaka’s theory (Eshelby in Proc R Soc Lond A 241(1226):376–396, 1957; Mori and Tanaka in Acta Metall 21(5):571–574, 1973), turgor pressure can be taken into account as a uniform strain acting on protoplasts. By using this Model, the relationship between the plant cell morphology changes, and their effective properties are derived with a theoretical basis.

  • a Micromechanics Model for turgor pressure of arabidopsis thaliana protoplast
    2014
    Co-Authors: Bochu Wang, Xingyan Yang, Yichuan Wang, Xue Fu
    Abstract:

    Understanding the key role of turgor pressure in plant growth and development is important for recognizing the mechanical behavior of plant cell wall material deposition. In this study, we developed a Micromechanics Model to demonstrate how uniaxial strain influences turgor pressure of isolated Arabidopsis thaliana protoplasts, and their deformation and morphogenesis. In this Model, the protoplast is treated as an elastic inclusion in a surrounding agarose gel, allowing the turgor pressure in response to the 20 % uniaxial strain exerted on the protoplast–agarose gel composite material system. Based on the Eshelby method and the Mori–Tanaka’s theory (Eshelby in Proc R Soc Lond A 241(1226):376–396, 1957; Mori and Tanaka in Acta Metall 21(5):571–574, 1973), turgor pressure can be taken into account as a uniform strain acting on protoplasts. By using this Model, the relationship between the plant cell morphology changes, and their effective properties are derived with a theoretical basis.