Using of Anisotropic Continuum Damage Mechanics to Describe Yield Surface Distortion

2015 ◽  
Vol 784 ◽  
pp. 11-18 ◽  
Author(s):  
Ali Nayebi ◽  
Hojjatollah Rokhgireh
Keyword(s):  
Yield Surface ◽  
Damage Mechanics ◽  
Internal State ◽  
Kinematic Hardening ◽  
Constitutive Relations ◽  
Internal Variables ◽  
Continuum Damage ◽  
Damage Potential ◽  
Surface Distortion ◽  
Yield Surface Distortion

In this paper, yield surface distortion was studied by considering the combination of nonlinear kinematic hardening model of Chaboche and a new anisotropic continuum damage evolution model. The constitutive relations for anisotropic damage of elastoplasic materials were developed based on irreversible thermodynamics. The internal state manifold which consists of internal variables to specify the thermodynamic state of solids was described by a 2nd rank symmetric damage tensor, the kinematic hardening tensor and tensor of movement of damage potential surface. In order to describe the damage state, the fictitious continuum domain was considered and the consistent relations between real and fictitious domains were developed. It was indicated that the combination of the Chaboche’s model and model of anisotropic continuum damage leads to the well description of the subsequent yield surface.

A New Model to Describe Yield Surface Distortion Based on the Baltov and Sawczuk’s Model

2012 ◽  
Author(s):  
A. Nayebi ◽  
H. Rokhgireh
Keyword(s):  
Yield Surface ◽  
Kinematic Hardening ◽  
Experimental Results ◽  
Surface Model ◽  
New Model ◽  
Surface Distortion ◽  
Loading Direction ◽  
Reverse Loading ◽  
Reversed Loading ◽  
Yield Surface Distortion

In the present study Baltov and Sawczuk’s yield surface model is modified to represent compatible results with experimental observations. The proposed yield surface is determined during tension-torsion loading by considering kinematic hardening model and monotonic loading paths. The experimental results represent the nosed and flattened region in the loading and reverse loading direction respectively. The nosed region is dominant in tension than in torsion. The cross-effect is negligible in the small plastic strain amount. The Baltov and Sawczuk’s yield surface has nosed and flattened regions in both loading and reversed loading directions for negative and positive added material parameter respectively. Thus the elliptic Baltov and Sawczuk’s yield surface is modified by changing the sign of this parameter continuously from loading to reverse loading direction and the needed relations of the new model are obtained. The new model was able to predict properly the shape of yield surface. The experimental results compare well with the new model yield surface distortion predictions.

Numerical simulation of sheet metal blanking based on fully coupled elastoplasticity-damage constitutive equations accounting for yield surface distortion-induced anisotropy

2016 ◽  
Vol 26 (7) ◽  
pp. 1061-1079 ◽  
Author(s):  
Zhenming Yue ◽  
Houssem Badreddine ◽  
Khemais Saanouni ◽  
Xincun Zhuang ◽  
Jun Gao
Keyword(s):  
Numerical Simulation ◽  
Sheet Metal ◽  
Yield Surface ◽  
Kinematic Hardening ◽  
Induced Anisotropy ◽  
Surface Distortion ◽  
Edge Quality ◽  
Blanking Process ◽  
Fully Coupled ◽  
Yield Surface Distortion

This paper deals with the numerical simulation of sheet metal blanking process based on fully coupled elastoplastic model accounting for the induced anisotropies due to the kinematic hardening and the yield surface distortion. The yield surface distortion is assumed to be controlled by the kinematic hardening leading additional extra hardening which enhances the predictive capabilities of the model. Series of finite element-based numerical simulations of blanking process with four kinds of assumed distortional hardening parameters have been conducted. Through the comparison between the experimentally observed responses and the numerically predicted ones with and without the yield surface distortion effect, the significance of the yield surface distortion-induced anisotropy on the estimation of the blanking edge quality has been investigated.

Shakedown-Ratcheting Analysis of a Spherical Pressure Vessel by Anisotropic Continuum Damage Mechanics

2018 ◽  
Author(s):  
Ali Nayebi ◽  
Azam Surmiri ◽  
Hojjatollah Rokhgireh
Keyword(s):  
Pressure Vessel ◽  
Damage Mechanics ◽  
Kinematic Hardening ◽  
Continuum Damage Mechanics ◽  
Mapping Method ◽  
Anisotropic Damage ◽  
Continuum Damage ◽  
Interaction Diagram ◽  
Plastic Shakedown ◽  
Spherical Pressure

In cyclic loading and when plastic flow occurs, discontinuities grow. In this research, interaction diagram of Bree has been developed when the spherical pressure vessel contains discontinuities such as voids and microcracks. Bree’s diagram is used for ratcheting assessment of pressurized equipment in ASME III NH. Nature of these defects leads to an anisotropic damage. Anisotropic Continuum Damage Mechanics (CDM) is considered to account effects of these discontinuities on the behavior of the structure. Shakedown – ratcheting response of a hollow sphere under constant internal pressure and cyclic thermal loadings are studied by using anisotropic CDM theory coupled with nonlinear kinematic hardening of Armstrong-Frederick m’s model (A-F). Return mapping method is used to solve numerically the developed relations. Elastic, elastic shakedown, plastic shakedown and ratcheting regions are illustrated in the modified Bree’s diagram. Influence of anisotropic damage due to the plastic deformation is studied and it was shown that the plastic shakedown region is diminished because of the developed damage.

Damage Mechanisms Modeling for Ceramic Composites

1994 ◽  
Vol 116 (3) ◽  
pp. 331-336 ◽  
Author(s):  
P. Ladeve`ze ◽  
A. Gasser ◽  
O. Allix
Keyword(s):  
Structural Analysis ◽  
Damage Mechanics ◽  
Constitutive Relations ◽  
Continuum Damage Mechanics ◽  
Ceramic Composites ◽  
Continuum Damage ◽  
Damage State ◽  
Damage Mechanisms ◽  
Final Fracture

For ceramic composites, continuum damage mechanics models are built, which include information coming from both the “micro” and “macro” scales. These models are constitutive relations which, when included in a structural analysis code, are able to predict the damage state of the studied structure at any time and at any point until final fracture.

A Theory of Multiaxial Anisotropic Viscoplasticity

1981 ◽  
Vol 48 (2) ◽  
pp. 276-284 ◽  
Author(s):  
M. A. Eisenberg ◽  
C.-F. Yen
Keyword(s):  
Yield Surface ◽  
Stress Space ◽  
Anisotropic Hardening ◽  
Surface Distortion ◽  
Induced Changes ◽  
Yield Surface Distortion

A theory of anisotropic viscoplasticity is developed. It is compared with and shown to reduce to existing theories under appropriate restrictions. The theory accommodates anisotropic hardening laws which, by means of Lagrangian mappings in stress space, incorporate experimentally observed yield surface distortion as well as kinematic and isotropic flow-induced changes. The theory is applied to the prediction of flow surfaces in tension-torsion space.

THE FOUNDATIONS OF CONTINUUM DAMAGE MECHANICS

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Siamak Yazdani ◽  
Sevenn Borgersen ◽  
Asli Pelin Gurgun ◽  
Hossein Nazari
Keyword(s):  
Damage Mechanics ◽  
Nonlinear Behavior ◽  
Continuum Damage Mechanics ◽  
Uniaxial Stress ◽  
Internal Variable ◽  
Continuum Damage ◽  
Damage Potential ◽  
Variable Theory ◽  
Wide Range ◽  
The Many

Damage Mechanics has become a useful theory in describing the nonlinear behavior of solids driven by the nucleation and growth of cracks and microcracks. This approach, based on the first principles of mechanics and thermodynamics, has also been combined with classical theories of plasticity to address a wide range of loading applications. In spite of the many different damage mechanics models and representations that are proposed, the foundation of damage mechanics is not well understood or at least not thoroughly published giving rise to the many inaccurate definitions and formulations. The intent of this paper is to provide the background of the continuum damage mechanics outlining the fundamentals on which this field theory is set up. The internal variable theory of continuum thermodynamics is reviewed and is shown that with Legendre transformation technique, various potential functions can be developed for damage mechanics formulation in either stress or strain space. The concept of constrained or neighboring equilibrium state is also introduced and is explained. The paper will conclude with the derivation of the general damage potential and a suggestion is given for the isotropic damage formulation with the resulting uniaxial stress-strain relation.

A Generalized Anisotropic Hardening Rule Based on the Mroz Multi-Yield-Surface Model

2008 ◽  
Author(s):  
K. S. Choi ◽  
J. Pan
Keyword(s):  
Cyclic Loading ◽  
Yield Surface ◽  
Kinematic Hardening ◽  
Constitutive Relations ◽  
Yield Function ◽  
Surface Model ◽  
Loading Conditions ◽  
Anisotropic Hardening ◽  
Hardening Rule ◽  
Strain Data

In this paper, a generalized anisotropic hardening rule based on the Mroz multi-yield-surface model is derived. The evolution equation for the active yield surface is obtained by considering the continuous expansion of the active yield surface during the unloading/reloading process. The incremental constitutive relation based on the associated flow rule is then derived for a general yield function. As a special case, detailed incremental constitutive relations are derived for the Mises yield function. The closed-form solutions for one-dimensional stress-plastic strain curves are also derived and plotted for the Mises materials under cyclic loading conditions. The stress-plastic strain curves show closed hysteresis loops under uniaxial cyclic loading conditions and the Masing hypothesis is applicable. A user material subroutine based on the Mises yield function, the anisotropic hardening rule and the constitutive relations was then written and implemented into ABAQUS. Computations were conducted for a simple plane strain finite element model under uniaxial monotonic and cyclic loading conditions based on the anisotropic hardening rule and the isotropic and nonlinear kinematic hardening rules of ABAQUS. The results indicate that the plastic response of the material follows the intended input stress-strain data for the anisotropic hardening rule whereas the plastic response depends upon the input strain ranges of the stress-strain data for the nonlinear kinematic hardening rule.

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