The Experts below are selected from a list of 24 Experts worldwide ranked by ideXlab platform
Matti Ristinmaa - One of the best experts on this subject based on the ideXlab platform.
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Deformation gradient based kinematic hardening model
International Journal of Plasticity, 2005Co-Authors: Mathias Wallin, Matti RistinmaaAbstract:A kinematic hardening model applicable to finite strains is presented. The kinematic hardening concept is based on the residual Stresses that evolve due to different obstacles that are present in a polycrystalline material, such as grain boundaries, cross slips, etc. Since these residual Stresses are a manifestation of the distortion of the crystal lattice a corresponding deformation gradient is introduced to represent this distortion. The residual Stresses are interpreted in terms of the form of a Back-Stress Tensor, i.e. the kinematic hardening model is based on a deformation gradient which determines the Back-Stress Tensor. A set of evolution equations is used to describe the evolution of the deformation gradient. Non-dissipative quantities are allowed in the model and the implications of these are discussed. Von Mises plasticity for which the uniaxial Stress–strain relation can be obtained in closed form serves as a model problem. For uniaxial loading, this model yields a kinematic hardening identical to the hardening produced by isotropic exponential hardening. The numerical implementation of the model is discussed. Finite element simulations showing the capabilities of the model are presented.
Paul Steinmann - One of the best experts on this subject based on the ideXlab platform.
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a framework for multiplicative elastoplasticity with kinematic hardening coupled to anisotropic damage
International Journal of Plasticity, 2005Co-Authors: Andreas Menzel, Magnus Ekh, Kenneth Runesson, Paul SteinmannAbstract:The objective of this contribution is the formulation and algorithmic treatment of a phenomenological framework to capture anisotropic geometrically nonlinear inelasticity. We consider in particular the coupling of viscoplasticity with anisotropic continuum damage whereby both, proportional and kinematic hardening are taken into account. As a main advantage of the proposed formulation standard continuum damage models with respect to a fictitious isotropic configuration can be adopted and conveniently extended to anisotropic continuum damage. The key assumption is based on the introduction of a damage tangent map that acts as an affine pre-deformation. Conceptually speaking, we deal with an Euclidian space with respect to a non-constant metric. The evolution of this field is directly related to the degradation of the material and allows the modeling of specific classes of elastic anisotropy. In analogy to the damage mapping we introduce an internal variable that determines a Back-Stress Tensor via a hyperelastic format and therefore enables the incorporation of plastic anisotropy. Several numerical examples underline the applicability of the proposed finite strain framework.
Mathias Wallin - One of the best experts on this subject based on the ideXlab platform.
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Deformation gradient based kinematic hardening model
International Journal of Plasticity, 2005Co-Authors: Mathias Wallin, Matti RistinmaaAbstract:A kinematic hardening model applicable to finite strains is presented. The kinematic hardening concept is based on the residual Stresses that evolve due to different obstacles that are present in a polycrystalline material, such as grain boundaries, cross slips, etc. Since these residual Stresses are a manifestation of the distortion of the crystal lattice a corresponding deformation gradient is introduced to represent this distortion. The residual Stresses are interpreted in terms of the form of a Back-Stress Tensor, i.e. the kinematic hardening model is based on a deformation gradient which determines the Back-Stress Tensor. A set of evolution equations is used to describe the evolution of the deformation gradient. Non-dissipative quantities are allowed in the model and the implications of these are discussed. Von Mises plasticity for which the uniaxial Stress–strain relation can be obtained in closed form serves as a model problem. For uniaxial loading, this model yields a kinematic hardening identical to the hardening produced by isotropic exponential hardening. The numerical implementation of the model is discussed. Finite element simulations showing the capabilities of the model are presented.
A Willuweit - One of the best experts on this subject based on the ideXlab platform.
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a comparative study of kinematic hardening rules at finite deformations
International Journal of Non-linear Mechanics, 2004Co-Authors: Ch Tsakmakis, A WilluweitAbstract:Abstract Kinematic hardening models describe a specific kind of plastic anisotropy which evolves with the deformation process. It is well known that the extension of constitutive relations from small to finite deformations is not unique. This applies also to well-established kinematic hardening rules like that of Armstrong–Frederick or Chaboche. However, the second law of thermodynamics offers some possibilities for generalizing constitutive equations so that this ambiguity may, in some extent, be moderated. The present paper is concerned with three possible extensions, from small to finite deformations, of the Armstrong–Frederick rule, which are derived as sufficient conditions for the validity of the second law. All three models rely upon the multiplicative decomposition of the deformation gradient Tensor into elastic and plastic parts and make use of a yield function expressed in terms of the so-called Mandel Stress Tensor. In conformity with this approach, the Back-Stress Tensor is defined to be of Mandel Stress type as well. In order to compare the properties of the three models, predicted responses for processes with homogeneous and inhomogeneous deformations are discussed. To this end, the models are implemented in a finite element code (ABAQUS).
Andreas Menzel - One of the best experts on this subject based on the ideXlab platform.
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a framework for multiplicative elastoplasticity with kinematic hardening coupled to anisotropic damage
International Journal of Plasticity, 2005Co-Authors: Andreas Menzel, Magnus Ekh, Kenneth Runesson, Paul SteinmannAbstract:The objective of this contribution is the formulation and algorithmic treatment of a phenomenological framework to capture anisotropic geometrically nonlinear inelasticity. We consider in particular the coupling of viscoplasticity with anisotropic continuum damage whereby both, proportional and kinematic hardening are taken into account. As a main advantage of the proposed formulation standard continuum damage models with respect to a fictitious isotropic configuration can be adopted and conveniently extended to anisotropic continuum damage. The key assumption is based on the introduction of a damage tangent map that acts as an affine pre-deformation. Conceptually speaking, we deal with an Euclidian space with respect to a non-constant metric. The evolution of this field is directly related to the degradation of the material and allows the modeling of specific classes of elastic anisotropy. In analogy to the damage mapping we introduce an internal variable that determines a Back-Stress Tensor via a hyperelastic format and therefore enables the incorporation of plastic anisotropy. Several numerical examples underline the applicability of the proposed finite strain framework.
