Research on Fracture Damage Coupled with Crack Arrest by Anchorage Model of Discontinuous Jointed Rock Mass under the State of Complex Stress

2007 ◽  
Vol 348-349 ◽  
pp. 189-192
Author(s):  
Le Wen Zhang ◽  
Shu Cai Li ◽  
Ying Wang
Keyword(s):  
Rock Mass ◽  
Constitutive Relation ◽  
Damage Evolution ◽  
Strain Energy ◽  
Damage Mechanics ◽  
Evolution Equations ◽  
Equivalent Strain ◽  
The State ◽  
Shear Stresses ◽  
Fracture Damage

Based on the hypothesis of equivalent strain energy and the theories of fracture mechanics and damage mechanics，the constitutive model and fracture damage mechanism of bolted discontinuous jointed rockmass are systematically studied under the state of complex stresses. Initially ， considering the equivalent strain energy ， the constitutive relation of anchored discontinuous jointed rockmass is derived under the state of compression-shear stresses. The constitutive relation under the state of tension-shear stresses is also developed according to the theory of self-consistence. Next，the damage evolution equations of discontinuous multi-crack rockmass under compression-shear and tension-shear are put forward according to the wing crack-initiating criterion. Finally，based on the above constitutive models and the damage evolution equations three-dimensional finite element procedures have been developed to evaluate the stability and deformability of the surrounding rock mass during excavation and supporting. The calculated results indicate that above-mentioned constitutive relation and the damage evolution equations are available.

Fracture-Damage Model for Anchored Discontinuous Jointed Rockmass and its Application

2007 ◽  
Vol 353-358 ◽  
pp. 973-976 ◽  
Author(s):  
Gang Wang ◽  
Shu Cai Li ◽  
Shu Gang Wang ◽  
Jing Long Li ◽  
Xiao Jing Li
Keyword(s):  
Constitutive Relation ◽  
Damage Mechanics ◽  
Damage Model ◽  
Three Dimensional ◽  
Damage Mechanism ◽  
Equivalent Strain ◽  
Complex Stress ◽  
The State ◽  
Constructive Model ◽  
Fracture Damage

According to the theories of fracture mechanics and damage mechanics, the constructive model and fracture damage mechanism of brittle discontinuous jointed rockmass are systematically studied under the state of complex stress in this paper. By the aid of the method of equivalent strain energy, the constitutive relation of anchored brittle discontinuous jointed rockmass is derived under the state of compression-shearing. The constitutive relation under the state of tension-shearing is also developed according to the theory of self-consistence. Finally, based on the above constructive models, the three-dimensional finite element procedure has been developed to model the ground movements that occur when underground power-houses of pumped-storage power station are installed in discontinuous jointed rockmass. The anchor supporting is an important component of this underground power-houses excavation work. Besides the displacement field and the secondary state of stress induced by the excavation disturbance, the effect of anchoring and the damage evolution around the power-houses have been particularly described during the process of installation. The numerical results obtained by numerical simulation were compared with that of field monitoring in order to verify the validity of the proposed models.

Parameter estimation of an anisotropic damage model for concrete using genetic algorithms

2015 ◽  
Vol 26 (6) ◽  
pp. 801-825 ◽  
Author(s):  
Muhammad A Wardeh ◽  
Houssam A Toutanji
Keyword(s):  
Damage Evolution ◽  
Elastic Strain ◽  
Strain Energy ◽  
Damage Mechanics ◽  
Evolution Equations ◽  
Damage Model ◽  
Elastic Strain Energy ◽  
Constitutive Law ◽  
Anisotropic Damage ◽  
Unknown Parameters

This article presents an anisotropic damage model for concrete that couples between elasticity and continuum damage mechanics. The formulation of constitutive model is based on the elastic strain energy in the framework of irreversible thermodynamics. The thermodynamic free energy is represented as a scalar function of elastic strain and damage tensors and used to derive the constitutive law and thermodynamic conjugate force of damage that is used to derive the dissipation potential. The damage evolution law is governed by the normality rule. The formulation of elastic strain energy of damaged material is capable of modeling the concrete anisotropic behavior under different loadings without decoupling the stress or damage release rate. A series of unknown parameters in the model formulation was used to control the constitutive behavior and damage surface. A Genetic algorithm FORTRAN subroutine is used to estimate these parameters based on the coupling between the constitutive and damage evolution equations. The performance of the damage model is verified with the experimental data from the literature. The model has shown a good agreement with the experimental results. It describes the anisotropy induced by the crack development within the concrete.

Viscoplastic Constitutive Modeling of Anisotropic Damage Under Nonproportional Loading

2000 ◽  
Vol 123 (4) ◽  
pp. 403-408 ◽  
Author(s):  
C. L. Chow ◽  
X. J. Yang ◽  
Edmund Chu
Keyword(s):  
Constitutive Modeling ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Evolution Equations ◽  
Forming Limit ◽  
Anisotropic Damage ◽  
Limit Curve ◽  
Forming Limit Curve ◽  
Localized Necking ◽  
Theory Of Damage

Based on the theory of damage mechanics, a viscoplastic constitutive modeling of anisotropic damage for the prediction of forming limit curve (FLC) is developed. The model takes into account the effect of rotation of principal damage coordinates on the deformation and damage behaviors. With the aid of the damage viscoplastic potential, the damage evolution equations are established. Based on a proposed damage criterion for localized necking, the model is employed to predict the FLC of aluminum 6111-T4 sheet alloy. The predicted results agree well with those determined experimentally.

Study on Anisotropic Fatigue Damage Model of Metal Component

2011 ◽  
Vol 21 (4) ◽  
pp. 599-620 ◽  
Author(s):  
Zhang Miao ◽  
Meng Qingchun ◽  
Hu Weiping ◽  
Zhang Xing
Keyword(s):  
Fatigue Life ◽  
Damage Evolution ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Evolution Equations ◽  
Prediction Method ◽  
Volume Element ◽  
Fatigue Life Prediction ◽  
Repeated Loading ◽  
Damage Evolution Equation

First of all, the boom–panel model is constructed to describe the anisotropic damage evolution of continuum volume element. The constitutive relation of continuum volume element is represented by damage extent of the booms and panels. Furthermore, based on irreversible thermodynamics, damage evolution equations of boom and panel are constructed. The fatigue life prediction method for smooth specimen under the repeated loading with constant strain amplitude is constructed. By the theory of conservative integral in damage mechanics, the fatigue life prediction method for notched specimen under the repeated loading with constant amplitude is obtained. Using these methods, the material parameters of LC4CS aluminum alloy in the damage evolution equation can be obtained by the mean values of experimental fatigue curves of standard specimens with KT = 1, K T = 3, and K T = 5. The computational results are in accordance with the experiment data.

On the Failure Locus of Isotropic Materials in the Stress Triaxiality Space

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
V. M. Manolopoulos ◽  
N. P. Andrianopoulos
Keyword(s):  
Elastic Strain ◽  
Strain Energy ◽  
Stress Triaxiality ◽  
Elastic Strain Energy ◽  
Equivalent Strain ◽  
Failure Behavior ◽  
Shear Stresses ◽  
Isotropic Materials ◽  
Single Criterion ◽  
Series Of Experiments

The aim of this paper is to contribute to the prediction of the failure of materials (ductile and brittle) with a single criterion (rule) not violating the assumptions of continuum mechanics. In this work, the failure behavior of isotropic materials is connected with the ability of a material to store elastic strain energy from the very start of loading until its fracture. This elastic strain energy is known that is separated in a distortional and a dilatational part. So, when one of these quantities takes a critical value, then the material fails either by slip or by cleavage. The behavior of a material is described with regard to the secant elastic moduli depending on both unit volume expansion Θ and equivalent strain ɛeq. This dependence enlightens, in physical terms, the different reaction of materials in normal and shear stresses. T-criterion is applied for the prediction of failure in a series of experiments that took place to an aluminum alloy (Al-5083) and to PMMA (Plexiglas). A single criterion was used for two totally different materials and the predictions are quite satisfactory. This work is a step toward the direction of using one criterion in order to explain and predict failure in materials independently of the plastic strain that developed before fracture.

Direct Tensile Performance of UHPCC Element Based on Damage Mechanics

2007 ◽  
Vol 348-349 ◽  
pp. 829-832 ◽  
Author(s):  
Sang Mook Han ◽  
Xiang Guo Wu ◽  
Sung Wook Kim ◽  
Su Tae Kang
Keyword(s):  
Constitutive Relation ◽  
Damage Evolution ◽  
High Performance ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Damage Evolution Equation ◽  
Nonlinear Analytical Model ◽  
Material Constitutive Relation ◽  
Modified Weibull ◽  
Direct Tensile

Direct uniaxial tension test of ultra high performance cementitious composites I shape specimens have been investigated in this paper. A nonlinear analytical model based on continuum damage mechanics is developed to characterize tensile stress-strain constitutive response of UHPCC. Basic governing equations of damage evolution and material constitutive relation are established considering random damage which conforms to a modified Weibull type distribution proposed in this paper. Calculation suggests that Weibull distribution can describe damage evolution of UHPCC and predict the constitutive relation and damage evolution equation.

Fatigue Damage Model for Numerical Assessment of Fatigue Characteristics

2008 ◽  
Vol 580-582 ◽  
pp. 663-666 ◽  
Author(s):  
Chi Seung Lee ◽  
Myung Hyun Kim ◽  
Min Sung Chun ◽  
Tak Kee Lee ◽  
Jae Myung Lee
Keyword(s):  
Damage Evolution ◽  
Damage Mechanics ◽  
Evolution Equations ◽  
Numerical Technique ◽  
Damage Model ◽  
Internal Damage ◽  
Numerical Assessment ◽  
Fatigue Characteristics ◽  
Evolution Behavior ◽  
Relationship Assessment

The aim of this study is the development of a numerical technique applicable for the fatigue assessment based on the damage mechanics approach. The generalized elasto-visco-plastic constitutive equation, which can consider the internal damage evolution behavior, is developed in order to numerically evaluate the material fatigue responses. Explicit information of the relationships between the mechanical properties and material constants, which are required for the mechanical constitutive and damage evolution equations, are derived. The performance of the developed technique has been verified using the S-N relationship assessment for STS304 stainless steel.

Viscoplastic Constitutive Modeling of Anisotropic Damage Under Nonproportional Loading

2000 ◽  
Author(s):  
C. L. Chow ◽  
X. J. Yang ◽  
Edmund Chu
Keyword(s):  
Constitutive Modeling ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Evolution Equations ◽  
Forming Limit ◽  
Anisotropic Damage ◽  
Limit Curve ◽  
Forming Limit Curve ◽  
Localized Necking ◽  
Theory Of Damage

Abstract Based on the theory of damage mechanics, a viscoplastic constitutive modeling of anisotropic damage for the prediction of forming limit curve (FLC) is developed. The model takes into account the effect of rotation of principal damage coordinates on the deformation and damage behaviors. With the aid of the damage viscoplastic potential, the damage evolution equations are established. Based on a proposed damage criterion for localized necking, the model is employed to predict the FLC of aluminum 6111-T4 sheet alloy. The predicted results agree well with those determined experimentally.

scholarly journals A continuum damage model for fatigue life prediction of 2.5D woven composites

2021 ◽  
Vol 28 (1) ◽  
pp. 653-667
Author(s):  
Nan Wang ◽  
Weidong Wen ◽  
Haitao Cui
Keyword(s):  
Fatigue Life ◽  
Damage Evolution ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Evolution Equations ◽  
Cell Model ◽  
Constitutive Relations ◽  
Fatigue Life Prediction ◽  
Woven Composites ◽  
Continuum Damage

Abstract A new model based on continuum damage mechanics is proposed to predict the fatigue life of 2.5D woven composites. First, a full-cell model reflecting the real microstructure of 2.5D woven composites is established in ANSYS. Subsequently, three independent damage variables are defined in the framework of the composite micromechanics to establish the component constitutive relations associated with damage. The strain energy density release rate and damage evolution equations for the matrix, fiber in yarns, and matrix in yarns are derived. Finally, the proposed model is implemented for fatigue life prediction and damage evolution analysis of 2.5D woven composites at 20 and 180°C. The results show that the numerical results are in good agreement with the relevant experimental results.

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