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Silvano Erlicher - One of the best experts on this subject based on the ideXlab platform.

  • bouc wen type models with stiffness degradation thermodynamic analysis and applications
    Journal of Engineering Mechanics-asce, 2008
    Co-Authors: Silvano Erlicher, Oreste S Bursi
    Abstract:

    In this paper, a thermodynamic analysis of Bouc–Wen models endowed with both strength and stiffness degradation is provided. This analysis is based on the relationship between the flow rules of these models and those of the Endochronic plasticity Theory with damage, discussed in a companion paper. Using the theoretical framework of that extended Endochronic Theory, it is shown that an elastic Bouc–Wen model with damage, i.e., without plastic strains, can be formulated. Moreover, a proper definition of the dissipated energy of these Bouc–Wen models with degradation is given and some thermodynamic constraints on the parameters defining the models behavior are emphasized and discussed. In particular, some properties of the energetic linear stiffness degradation rule as well as the so-called pivot rule, well known in the seismic engineering field, are illustrated and commented upon. An improved energetic stiffness degradation rule and a new stiffness degradation rule are proposed.

  • pseudopotentials and loading surfaces for an Endochronic plasticity Theory with isotropic damage
    Journal of Engineering Mechanics-asce, 2008
    Co-Authors: Silvano Erlicher, Nelly Point
    Abstract:

    The Endochronic Theory, developed in the early 70s, allows the plastic behavior of materials to be represented by introducing the notion of intrinsic time. With different viewpoints, several authors discussed the relationship between this Theory and the classical Theory of plasticity. Two major differences are the presence of plastic strains during unloading phases and the absence of an elastic domain. Later, the Endochronic plasticity Theory was modified in order to introduce the effect of damage. In the present paper, a basic Endochronic model with isotropic damage is formulated starting from the postulate of strain equivalence. Unlike the previous similar analyses, in this presentation the formal tools chosen to formulate the model are those of convex analysis, often used in classical plasticity: namely pseudopotentials, indicator functions, subdifferentials, etc. As a result, the notion of loading surface for an Endochronic model of plasticity with damage is investigated and an insightful comparison w...

  • Pseudo-potentials and loading surfaces for an Endochronic plasticity Theory with isotropic damage
    Journal of Engineering Mechanics, 2008
    Co-Authors: Silvano Erlicher, Nelly Point
    Abstract:

    The Endochronic Theory, developed in the early 70s, allows the plastic behavior of materials to be represented by introducing the notion of intrinsic time. With different viewpoints, several authors discussed the relationship between this Theory and the classical Theory of plasticity. Two major differences are the presence of plastic strains during unloading phases and the absence of an elastic domain. Later, the Endochronic plasticity Theory was modified in order to introduce the effect of damage. In the present paper, a basic Endochronic model with isotropic damage is formulated starting from the postulate of strain equivalence. Unlike the previous similar analyses, in this presentation the formal tools chosen to formulate the model are those of convex analysis, often used in classical plasticity: namely pseudopotentials, indicator functions, subdifferentials, etc. As a result, the notion of loading surface for an Endochronic model of plasticity with damage is investigated and an insightful comparison with classical models is made possible. A damage pseudopotential definition allowing a very general damage evolution is given.

  • Bouc-Wen-type models with stiffness degradation: thermodynamic analysis and applications
    Journal of Engineering Mechanics, 2008
    Co-Authors: Silvano Erlicher, Oreste S Bursi
    Abstract:

    In this paper, a thermodynamic analysis of Bouc-Wen models endowed with both strength and stiffness degradation is provided. It is based on the relationship between the flow rules of these models and those of the Endochronic plasticity Theory with damage, discussed in a companion paper (Erlicher and Point, 2008). Using the theoretical framework of that extended Endochronic Theory, it is shown that an elastic Bouc-Wen model with damage, i.e. without plastic strains, can be formulated. Moreover, a proper definition of the dissipated energy of these Bouc-Wen models with degradation is given and some thermodynamic constraints on the parameters defining the models behavior are emphasized and discussed. In particular, some properties of the energetic linear stiffness degradation rule as well as the so-called pivot rule, well-known in the seismic engineering field, are illustrated and commented upon. An improved energetic stiffness degradation rule and a new stiffness degradation rule are proposed.

  • Endochronic Theory, non-linear kinematic hardening rule and generalized plasticity: a new interpretation based on generalized normality assumption
    International Journal of Solids and Structures, 2006
    Co-Authors: Silvano Erlicher, Nelly Point
    Abstract:

    A simple way to define the flow rules of plasticity models is the assumption of generalized normality associated with a suitable pseudo-potential function. This approach, however, is not usually employed to formulate Endochronic Theory and non-linear kinematic (NLK) hardening rules as well as generalized plasticity models. In this paper, generalized normality is used to give a new formulation of these classes of models. As a result, a suited pseudo-potential is introduced for Endochronic models and a non-standard description of NLK hardening and generalized plasticity models is also provided. This new formulation allows for an effective investigation of the relationships between these three classes of plasticity models.

Meera N K Singh - One of the best experts on this subject based on the ideXlab platform.

Gbadebo Owolabi - One of the best experts on this subject based on the ideXlab platform.

  • a comparison between two analytical models that approximate notch root elastic plastic strain stress components in two phase particle reinforced metal matrix composites under multiaxial cyclic loading Theory
    International Journal of Fatigue, 2006
    Co-Authors: Gbadebo Owolabi, Meera N K Singh
    Abstract:

    Abstract In this paper, two analytical models for estimating surface notch-root elastic–plastic, strain–stress histories in particulate metal matrix composites (PMMCs) when subjected to multiaxial cyclic loads are presented and compared. The models are based on the concept of incremental average stress, the Endochronic Theory of plasticity, and modified forms of the incremental equivalent strain energy density method (ESED) and Neuber's rule. Each model provides a complete set of equations capable of predicting the elastic–plastic strain–stress histories at the notch root given a corresponding elastic solution. The preliminary analytical results obtained by applying the formulations to a circumferentially notched round bar show that each model can independently be used to predict the nonlinear heterogeneous behavior at the notch root in PMMC components.

  • notch root elastic plastic strain stress in particulate metal matrix composites subjected to general loading conditions
    Journal of Astm International, 2005
    Co-Authors: Gbadebo Owolabi, Mnk Singh
    Abstract:

    Determining the stress and strain history at the point of highest stress concentration in particulate metal matrix composites (PMMCs) is complicated, particularly when they have a finite concentration of inclusions, the matrix material in the vicinity of the notch is elastic-plastic, and when multiaxial cyclic loads are applied to the component. In this paper, an analytical tool is developed to approximate notch root elastic-plastic strains and stresses in PMMC components subjected to multiaxial cyclic loads. The model consists of a set of linear relations that can be solved to estimate a notch root elastic-plastic strain and stress history in PMMCs from an elastic analysis. The model is developed using assumptions about notch root behavior, the incremental mean field Theory, and the Endochronic Theory of plasticity. The model presented provides an easy to implement approximation to the otherwise rather complex non-linear problem. The analytical results are compared to the local strains, obtained using 3D image correlation technology, at the depth of a circumferential notch in a PMMC bar subjected to proportional and non-proportionally applied monotonic and cyclic axial-torsional loads. The results of the comparison show that the proposed model works well for the geometry and load paths considered.

Nelly Point - One of the best experts on this subject based on the ideXlab platform.

  • pseudopotentials and loading surfaces for an Endochronic plasticity Theory with isotropic damage
    Journal of Engineering Mechanics-asce, 2008
    Co-Authors: Silvano Erlicher, Nelly Point
    Abstract:

    The Endochronic Theory, developed in the early 70s, allows the plastic behavior of materials to be represented by introducing the notion of intrinsic time. With different viewpoints, several authors discussed the relationship between this Theory and the classical Theory of plasticity. Two major differences are the presence of plastic strains during unloading phases and the absence of an elastic domain. Later, the Endochronic plasticity Theory was modified in order to introduce the effect of damage. In the present paper, a basic Endochronic model with isotropic damage is formulated starting from the postulate of strain equivalence. Unlike the previous similar analyses, in this presentation the formal tools chosen to formulate the model are those of convex analysis, often used in classical plasticity: namely pseudopotentials, indicator functions, subdifferentials, etc. As a result, the notion of loading surface for an Endochronic model of plasticity with damage is investigated and an insightful comparison w...

  • Pseudo-potentials and loading surfaces for an Endochronic plasticity Theory with isotropic damage
    Journal of Engineering Mechanics, 2008
    Co-Authors: Silvano Erlicher, Nelly Point
    Abstract:

    The Endochronic Theory, developed in the early 70s, allows the plastic behavior of materials to be represented by introducing the notion of intrinsic time. With different viewpoints, several authors discussed the relationship between this Theory and the classical Theory of plasticity. Two major differences are the presence of plastic strains during unloading phases and the absence of an elastic domain. Later, the Endochronic plasticity Theory was modified in order to introduce the effect of damage. In the present paper, a basic Endochronic model with isotropic damage is formulated starting from the postulate of strain equivalence. Unlike the previous similar analyses, in this presentation the formal tools chosen to formulate the model are those of convex analysis, often used in classical plasticity: namely pseudopotentials, indicator functions, subdifferentials, etc. As a result, the notion of loading surface for an Endochronic model of plasticity with damage is investigated and an insightful comparison with classical models is made possible. A damage pseudopotential definition allowing a very general damage evolution is given.

  • Endochronic Theory, non-linear kinematic hardening rule and generalized plasticity: a new interpretation based on generalized normality assumption
    International Journal of Solids and Structures, 2006
    Co-Authors: Silvano Erlicher, Nelly Point
    Abstract:

    A simple way to define the flow rules of plasticity models is the assumption of generalized normality associated with a suitable pseudo-potential function. This approach, however, is not usually employed to formulate Endochronic Theory and non-linear kinematic (NLK) hardening rules as well as generalized plasticity models. In this paper, generalized normality is used to give a new formulation of these classes of models. As a result, a suited pseudo-potential is introduced for Endochronic models and a non-standard description of NLK hardening and generalized plasticity models is also provided. This new formulation allows for an effective investigation of the relationships between these three classes of plasticity models.

Erlicher Silvano - One of the best experts on this subject based on the ideXlab platform.

  • Bouc-Wen-type models with stiffness degradation: thermodynamic analysis and applications
    'American Society of Civil Engineers (ASCE)', 2008
    Co-Authors: Erlicher Silvano, Bursi Oreste
    Abstract:

    International audienceIn this paper, a thermodynamic analysis of Bouc-Wen models endowed with both strength and stiffness degradation is provided. It is based on the relationship between the flow rules of these models and those of the Endochronic plasticity Theory with damage, discussed in a companion paper (Erlicher and Point, 2008). Using the theoretical framework of that extended Endochronic Theory, it is shown that an elastic Bouc-Wen model with damage, i.e. without plastic strains, can be formulated. Moreover, a proper definition of the dissipated energy of these Bouc-Wen models with degradation is given and some thermodynamic constraints on the parameters defining the models behavior are emphasized and discussed. In particular, some properties of the energetic linear stiffness degradation rule as well as the so-called pivot rule, well-known in the seismic engineering field, are illustrated and commented upon. An improved energetic stiffness degradation rule and a new stiffness degradation rule are proposed

  • Pseudo-potentials and loading surfaces for an Endochronic plasticity Theory with isotropic damage
    'American Society of Civil Engineers (ASCE)', 2008
    Co-Authors: Erlicher Silvano, Point Nelly
    Abstract:

    International audienceThe Endochronic Theory, developed in the early 70s, allows the plastic behavior of materials to be represented by introducing the notion of intrinsic time. With different viewpoints, several authors discussed the relationship between this Theory and the classical Theory of plasticity. Two major differences are the presence of plastic strains during unloading phases and the absence of an elastic domain. Later, the Endochronic plasticity Theory was modified in order to introduce the effect of damage. In the present paper, a basic Endochronic model with isotropic damage is formulated starting from the postulate of strain equivalence. Unlike the previous similar analyses, in this presentation the formal tools chosen to formulate the model are those of convex analysis, often used in classical plasticity: namely pseudopotentials, indicator functions, subdifferentials, etc. As a result, the notion of loading surface for an Endochronic model of plasticity with damage is investigated and an insightful comparison with classical models is made possible. A damage pseudopotential definition allowing a very general damage evolution is given

  • Endochronic Theory, non-linear kinematic hardening rule and generalized plasticity: a new interpretation based on generalized normality assumption
    'Elsevier BV', 2006
    Co-Authors: Erlicher Silvano, Point Nelly
    Abstract:

    International audienceA simple way to define the flow rules of plasticity models is the assumption of generalized normality associated with a suitable pseudo-potential function. This approach, however, is not usually employed to formulate Endochronic Theory and non-linear kinematic (NLK) hardening rules as well as generalized plasticity models. In this paper, generalized normality is used to give a new formulation of these classes of models. As a result, a suited pseudo-potential is introduced for Endochronic models and a non-standard description of NLK hardening and generalized plasticity models is also provided. This new formulation allows for an effective investigation of the relationships between these three classes of plasticity models

  • Thermodynamic admissibility of Bouc-Wen type hysteresis models
    'Elsevier BV', 2004
    Co-Authors: Erlicher Silvano, Point Nelly
    Abstract:

    International audienceStarting from the relationship between the Bouc model and the Endochronic Theory and by adopting some new intrinsic time measures, the thermodynamic admissibility of the Bouc-Wen model is proved, in the univariate case as well as in the tensorial one. Moreover, the proposed proof encompasses the cases where a strength degradation term appears