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

  • a three invariant cap model with isotropic kinematic hardening rule and associated Plasticity for granular materials
    International Journal of Solids and Structures, 2008
    Co-Authors: H Dormohammadi, A R Khoei
    Abstract:

    Abstract In this paper, a three-invariant cap model is developed for the isotropic–kinematic hardening and associated Plasticity of granular materials. The model is based on the concepts of elasticity and Plasticity theories together with an associated flow rule and a work hardening law for Plastic deformations of granulars. The hardening rule is defined by its decomposition into the isotropic and kinematic material functions. The constitutive elasto-Plastic Matrix and its components are derived by using the definition of yield surface, material functions and non-linear elastic behavior, as function of hardening parameters. The model assessment and procedure for determination of material parameters are described. Finally, the applicability of proposed Plasticity model is demonstrated in numerical simulation of several triaxial and confining pressure tests on different granular materials, including: wheat, rape, synthetic granulate and sand.

  • a three invariant cap Plasticity with isotropic kinematic hardening rule for powder materials model assessment and parameter calibration
    Computational Materials Science, 2007
    Co-Authors: A R Khoei, H Dormohammadi
    Abstract:

    Abstract The constitutive modeling of powder is clearly a keystone of successful quantitative solution possibilities. Without a reasonable constitutive model, which can reproduce complicated powder behavior under loading conditions, the computations are worthless. In this paper, a three-invariant cap Plasticity model with isotropic–kinematic hardening rule is presented for powder materials. A generalized single-cap Plasticity is developed which can be compared with some common double-surface Plasticity models proposed for powders in literature. The hardening rule is defined based on the isotropic and kinematic material functions. The constitutive elasto-Plastic Matrix and its components are derived by using the definition of yield surface, material functions and nonlinear elastic behavior, as function of hardening parameters. The procedure for determination of material parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.

  • a three invariant cap Plasticity model with kinematic hardening rule for powder materials
    Journal of Materials Processing Technology, 2007
    Co-Authors: A R Khoei, H Dormohammadi, A R Azami
    Abstract:

    Abstract In this paper, a three-invariant cap Plasticity with a kinematic hardening rule is presented for powder materials. A general form is developed for the cap Plasticity which can be compared with some common double-surface Plasticity models proposed for powders in literature. The constitutive elasto-Plastic Matrix and its components are derived based on the definition of yield surface, hardening parameter and non-linear elastic behavior, as function of relative density of powder. The procedure for determination of powder parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.

  • a single cone cap Plasticity with an isotropic hardening rule for powder materials
    International Journal of Mechanical Sciences, 2005
    Co-Authors: A R Khoei, A R Azami
    Abstract:

    Abstract In this paper, a new single cone-cap Plasticity with an isotropic hardening rule is presented for powder materials. A general form is developed for the cap Plasticity, which can be compared with some common double-surface Plasticity models proposed for powders in literature. The constitutive elasto-Plastic Matrix and its components are derived based on the definition of yield surface, hardening parameter and nonlinear elastic behavior, as a function of relative density of powder. Different aspects of the model are illustrated and the procedure for determination of powder parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.

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

  • a three invariant cap Plasticity model with kinematic hardening rule for powder materials
    Journal of Materials Processing Technology, 2007
    Co-Authors: A R Khoei, H Dormohammadi, A R Azami
    Abstract:

    Abstract In this paper, a three-invariant cap Plasticity with a kinematic hardening rule is presented for powder materials. A general form is developed for the cap Plasticity which can be compared with some common double-surface Plasticity models proposed for powders in literature. The constitutive elasto-Plastic Matrix and its components are derived based on the definition of yield surface, hardening parameter and non-linear elastic behavior, as function of relative density of powder. The procedure for determination of powder parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.

  • 3d computational modeling of powder compaction processes using a three invariant hardening cap Plasticity model
    Finite Elements in Analysis and Design, 2006
    Co-Authors: A R Azami
    Abstract:

    In this paper, a three-invariant cap Plasticity is developed for description of powder behavior under cold compaction process. The constitutive elasto-Plastic Matrix and its components are derived as the nonlinear functions of powder relative density. Different aspects of 2D and 3D cap Plasticity models are illustrated and the procedure for determination of powder parameters is described. It is shown how the proposed model could generate the elliptical yield surface, double-surface cap Plasticity and the irregular hexagonal pyramid of the Mohr-Coulomb and cone-cap yield surface, as special cases. The single-cap Plasticity is performed within the framework of large finite element deformation, in order to predict the nonuniform relative density distribution during powder die pressing. Finally, the applicability of the proposed model for description of powder behavior is demonstrated in numerical simulation of triaxial and confining pressure tests. The numerical schemes are examined for efficiency in the modeling of an automotive component, a conical shaped-charge liner and a connecting-rod.

  • a single cone cap Plasticity with an isotropic hardening rule for powder materials
    International Journal of Mechanical Sciences, 2005
    Co-Authors: A R Khoei, A R Azami
    Abstract:

    Abstract In this paper, a new single cone-cap Plasticity with an isotropic hardening rule is presented for powder materials. A general form is developed for the cap Plasticity, which can be compared with some common double-surface Plasticity models proposed for powders in literature. The constitutive elasto-Plastic Matrix and its components are derived based on the definition of yield surface, hardening parameter and nonlinear elastic behavior, as a function of relative density of powder. Different aspects of the model are illustrated and the procedure for determination of powder parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.

Giuseppe Vairo - One of the best experts on this subject based on the ideXlab platform.

  • nanoporous materials with a general isotropic Plastic Matrix exact limit state under isotropic loadings
    International Journal of Plasticity, 2017
    Co-Authors: Stella Brach, Luc Dormieux, Djimedo Kondo, Giuseppe Vairo
    Abstract:

    Abstract In this paper, hydrostatic strength properties of nanoporous materials are investigated by addressing the limit state of a hollow sphere undergoing isotropic loading conditions. Void-size effects are modelled by treating the cavity boundary as a coherent-imperfect homogeneous interface. The hollow sphere is assumed to be comprised of a rigid-ideal-Plastic material obeying to a general isotropic yield criterion. The latter is defined by considering a simplified form of the yield function proposed by Bigoni and Piccolroaz in [Int J Solids Struct; 41: 2855–2878], resulting able to account for a broad class of pressure-sensitive materials whose Plastic response is also affected by the stress Lode angle. The corresponding support function is consistently derived and discussed. The exact solution of the limit-state problem is fully determined, providing a closed-form description of stress, strain-rate and velocity fields, as well as the macroscopic hydrostatic strength of nanoporous media. Proposed approach allows to consistently generalise available analytical solutions for porous and nanoporous materials, by accounting for a general Plastic response of the solid Matrix and for void-size effects. Finally, present exact solution, as well as the identification of the support function for the adopted general strength criterion, open towards novel kinematic limit-analysis approaches for describing macroscale strength properties of nanoporous materials under arbitrary triaxial loadings.

  • deviatoric strength of nanoporous materials a limit analysis approach
    2017
    Co-Authors: Stella Brach, Luc Dormieux, Djimedo Kondo, Giuseppe Vairo
    Abstract:

    In this paper, deviatoric strength properties of nanoporous materials are investigated by addressing the limit state of a hollow sphere undergoing axisymmetric deviatoric strain-rate based loading conditions. The hollow sphere is assumed to be comprised of a rigid ideal-Plastic Matrix obeying to a von Mises strength criterion. Void-size effects are consistently described by introducing a coherent-imperfect homogeneous interface at the cavity boundary. In the framework of a kinematic approach, the limit-analysis problem on the hollow sphere is solved by referring to a particular trial velocity field, expressed in terms of some free model parameters, chosen as a result of an optimization strategy. A closed-form expression for estimating the macroscopic deviatoric strength is obtained and successfully compared with available benchmarking data.

H Dormohammadi - One of the best experts on this subject based on the ideXlab platform.

  • a three invariant cap model with isotropic kinematic hardening rule and associated Plasticity for granular materials
    International Journal of Solids and Structures, 2008
    Co-Authors: H Dormohammadi, A R Khoei
    Abstract:

    Abstract In this paper, a three-invariant cap model is developed for the isotropic–kinematic hardening and associated Plasticity of granular materials. The model is based on the concepts of elasticity and Plasticity theories together with an associated flow rule and a work hardening law for Plastic deformations of granulars. The hardening rule is defined by its decomposition into the isotropic and kinematic material functions. The constitutive elasto-Plastic Matrix and its components are derived by using the definition of yield surface, material functions and non-linear elastic behavior, as function of hardening parameters. The model assessment and procedure for determination of material parameters are described. Finally, the applicability of proposed Plasticity model is demonstrated in numerical simulation of several triaxial and confining pressure tests on different granular materials, including: wheat, rape, synthetic granulate and sand.

  • a three invariant cap Plasticity with isotropic kinematic hardening rule for powder materials model assessment and parameter calibration
    Computational Materials Science, 2007
    Co-Authors: A R Khoei, H Dormohammadi
    Abstract:

    Abstract The constitutive modeling of powder is clearly a keystone of successful quantitative solution possibilities. Without a reasonable constitutive model, which can reproduce complicated powder behavior under loading conditions, the computations are worthless. In this paper, a three-invariant cap Plasticity model with isotropic–kinematic hardening rule is presented for powder materials. A generalized single-cap Plasticity is developed which can be compared with some common double-surface Plasticity models proposed for powders in literature. The hardening rule is defined based on the isotropic and kinematic material functions. The constitutive elasto-Plastic Matrix and its components are derived by using the definition of yield surface, material functions and nonlinear elastic behavior, as function of hardening parameters. The procedure for determination of material parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.

  • a three invariant cap Plasticity model with kinematic hardening rule for powder materials
    Journal of Materials Processing Technology, 2007
    Co-Authors: A R Khoei, H Dormohammadi, A R Azami
    Abstract:

    Abstract In this paper, a three-invariant cap Plasticity with a kinematic hardening rule is presented for powder materials. A general form is developed for the cap Plasticity which can be compared with some common double-surface Plasticity models proposed for powders in literature. The constitutive elasto-Plastic Matrix and its components are derived based on the definition of yield surface, hardening parameter and non-linear elastic behavior, as function of relative density of powder. The procedure for determination of powder parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.

Stella Brach - One of the best experts on this subject based on the ideXlab platform.

  • nanoporous materials with a general isotropic Plastic Matrix exact limit state under isotropic loadings
    International Journal of Plasticity, 2017
    Co-Authors: Stella Brach, Luc Dormieux, Djimedo Kondo, Giuseppe Vairo
    Abstract:

    Abstract In this paper, hydrostatic strength properties of nanoporous materials are investigated by addressing the limit state of a hollow sphere undergoing isotropic loading conditions. Void-size effects are modelled by treating the cavity boundary as a coherent-imperfect homogeneous interface. The hollow sphere is assumed to be comprised of a rigid-ideal-Plastic material obeying to a general isotropic yield criterion. The latter is defined by considering a simplified form of the yield function proposed by Bigoni and Piccolroaz in [Int J Solids Struct; 41: 2855–2878], resulting able to account for a broad class of pressure-sensitive materials whose Plastic response is also affected by the stress Lode angle. The corresponding support function is consistently derived and discussed. The exact solution of the limit-state problem is fully determined, providing a closed-form description of stress, strain-rate and velocity fields, as well as the macroscopic hydrostatic strength of nanoporous media. Proposed approach allows to consistently generalise available analytical solutions for porous and nanoporous materials, by accounting for a general Plastic response of the solid Matrix and for void-size effects. Finally, present exact solution, as well as the identification of the support function for the adopted general strength criterion, open towards novel kinematic limit-analysis approaches for describing macroscale strength properties of nanoporous materials under arbitrary triaxial loadings.

  • deviatoric strength of nanoporous materials a limit analysis approach
    2017
    Co-Authors: Stella Brach, Luc Dormieux, Djimedo Kondo, Giuseppe Vairo
    Abstract:

    In this paper, deviatoric strength properties of nanoporous materials are investigated by addressing the limit state of a hollow sphere undergoing axisymmetric deviatoric strain-rate based loading conditions. The hollow sphere is assumed to be comprised of a rigid ideal-Plastic Matrix obeying to a von Mises strength criterion. Void-size effects are consistently described by introducing a coherent-imperfect homogeneous interface at the cavity boundary. In the framework of a kinematic approach, the limit-analysis problem on the hollow sphere is solved by referring to a particular trial velocity field, expressed in terms of some free model parameters, chosen as a result of an optimization strategy. A closed-form expression for estimating the macroscopic deviatoric strength is obtained and successfully compared with available benchmarking data.