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.

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.

Study on Damage Evolution Mechanism of Concrete under Uniaxial Tension

2012 ◽  
Vol 238 ◽  
pp. 46-50
Author(s):  
Wei Feng Bai ◽  
Ying Cui ◽  
Qian Wang ◽  
Jun Feng Guan ◽  
Jian Wei Zhang
Keyword(s):  
Uniaxial Tension ◽  
Damage Mechanics ◽  
Failure Process ◽  
Damage Model ◽  
Damage Mechanism ◽  
Deformation Characteristics ◽  
Deformation And Failure ◽  
Damage And Failure ◽  
Basic Parameters ◽  
Fundamental Research

The damage and failure mechanism of quasi-brittle materials is the most fundamental research topic in Damage Mechanics. In this paper, the mesoscopic damage mechanism of concrete under uniaxial tension was discussed. The rupture and yield damage modes in meso-scale were introduced as the two basic parameters to define the damage accumulated variable. The results show that the proposed statistical damage model can accurately predict the whole deformation and failure process of concrete under uniaxial tension, including the two-stage deformation characteristics and the size effect.

A Coupled Elastic-Plastic Damage Model for Rock Material

2014 ◽  
Vol 488-489 ◽  
pp. 799-802
Author(s):  
Hong Jie Chen ◽  
Wei Ya Xu ◽  
Ru Bin Wang ◽  
Wei Wang
Keyword(s):  
Damage Mechanics ◽  
Damage Model ◽  
Confining Pressure ◽  
Damage Mechanism ◽  
Coupling Model ◽  
Internal Variable ◽  
Elastic Plastic ◽  
Softening Behavior ◽  
Plastic Damage ◽  
Damage Constitutive Model

With complex mechanics character and under the action of compression and tension in tri-direction, rock will show coupled plastic-damage mechanism as its basic character. Phenomenological coupled elastic-plastic-damage constitutive model with internal variable is proposed based on thermal mechanics theory, elastic law and macro damage mechanics. Numerical experiments on this model and analyze the model character. The result shows that the coupling model could realize rocks softening behavior brought about by damage and strength enlargement caused by confining pressure increasing.

A Deformation and Life Prediction of a Circumferentially Reinforced SiC/Ti 15-3 Ring

1993 ◽  
Author(s):  
S. M. Arnold ◽  
T. E. Wilt
Keyword(s):  
Finite Element ◽  
Stress Analysis ◽  
Damage Mechanics ◽  
Damage Model ◽  
Three Dimensional ◽  
Life Assessment ◽  
Burst Pressure ◽  
Internal Damage ◽  
Current Application ◽  
The Matrix

Abstract A computational methodology has been developed to predict the fatigue life of typical aerospace components, here the specific example is a circumferentially reinforced SiC/Ti-15-3 compressor ring designed for applications at 800° F. The analysis encompasses both a static burst pressure prediction and a life assessment of the cladded ring. A three dimensional stress analysis was performed using MARC, a nonlinear finite element code, wherein both the matrix cladding and the composite core were assumed to behave elastic-plastic. The composite core behaviour was represented using Hill’s anisotropic continuum based plasticity model with bilinear hardening. Similarity, the matrix cladding was represented by an isotropic perfectly plastic model. The load-displacement (i.e., internal pressure versus radial deflection) response of the ring was used to determine the static burst pressure. The life assessment was conducted using the stress analysis results, in conjunction with a recently developed multiaxial, isothermal, continuum damage mechanics model for the fatigue of unidirectional metal matrix composites. This model is phenomenological, stress based, and assumes a single scalar internal damage variable, the evolution of which is anisotropic. The accumulation of damage is included in the stress analysis by employing the concept of effective stress. In the current application, however, the damage model is computationally-decoupled from the finite element solution. The specific methodology for this computationally-decoupled fatigue damage simulation is outlined and results are given in terms of the evolution of damage and design life curves.

On the Utilization of Shear Modified GTN Damage Model in Cold Rolling

2015 ◽  
Vol 750 ◽  
pp. 47-50
Author(s):  
Quan Sun ◽  
Da Qian Zan ◽  
Hong Liang Pan ◽  
Jian Jun Chen
Keyword(s):  
Cold Rolling ◽  
Fracture Behavior ◽  
Steel Strip ◽  
Damage Model ◽  
Damage Mechanism ◽  
Rolling Process ◽  
Complex Stress ◽  
Damage And Fracture ◽  
Rolling Experiment ◽  
Gtn Damage Model

Edge cracking is a commonly observed phenomenon in cold rolling process, but researchers appear to be far from fully understanding its failure mechanism due to the complex stress conditions of steel strip under the rolling condition. In this research, the shear modified GTN damage model coupled with Nahshon-Hutchinson shear damage mechanism was applied to investigate the damage and fracture behavior of steel strip in cold rolling. The results show that the shear modified GTN damage model is competent to predict the damage and fracture behavior of steel strip in cold rolling. By comparison to the cold rolling experiment, it presents that the prediction of edge crack occurrence of the shear modified GTN damage model is more accurate than that of the original GTN damage model.

Continuum Damage Mechanics Studies on the Dynamic Fracture of Concrete

1985 ◽  
Vol 64 ◽  
Author(s):  
E. P. Chen
Keyword(s):  
Dynamic Fracture ◽  
Damage Mechanics ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Damage Mechanism ◽  
Continuum Damage ◽  
Strain Rate Effects ◽  
Perfectly Plastic ◽  
Material Stiffness ◽  
Elastic Perfectly Plastic

ABSTRACTThe dynamic fracture of concrete in tension is studied by applying a continuum damage model developed by the author and his coworkers [1–3]. In this model, the degree of damage in concrete corresponds to the fraction of concrete volume that has been tension relieved, and tensile microcracking has been taken as the damage mechanism. In compression, the concrete is assumed to respond in an elastic/perfectly plastic manner. Strain-rate effects have been explicitly included in the model. Accumulation of damage in the material is reflected by the progressive weakening of the material stiffness. Examples involving center- and edge-cracked plate specimens subjected to the action of step and ramp loads are used to demonstrate the material responses predicted by the model. The bulk pressure versus strain relationships at locations close to the crack tip clearly show strainsoftening behavior. The damage tends to localize around the crack and its extent in the specimen is dependent upon both the crack geometry and the loading type. These results are presented and their implications are discussed.

Creep damage model considering unilateral effect based on bimodulus theory

2021 ◽  
pp. 105678952110173
Author(s):  
Yuhao Guo ◽  
Gang Liu ◽  
Huaqing Liu ◽  
Yi Huang
Keyword(s):  
Damage Mechanics ◽  
Damage Model ◽  
Creep Damage ◽  
Uniaxial Stress ◽  
Complex Stress ◽  
Principal Stresses ◽  
Numerical Example ◽  
Proposed Model ◽  
Stress States ◽  
Creep Damage Model

Based on the continuous damage mechanics (CDM) theory, Ambartsumyan bimodulus theory and creep damage theory, a bimodulus creep damage constitutive model is proposed in this paper. The model is able to describe the damage-induced unilateral behaviour related to the microdefect closure effect. The unilateral behaviour is considered a special bimodulus property. By judging the tension or compression state in bimodulus theory, different elasticity properties matrixes are selected according to signs of principal stresses. Then, an elasticity properties matrix is linearly converted to a general stress space. The model effectively solves the difficulty of determining tension or compression in complex stress states when the unilateral effect of damage is considered in the analysis of actual structures. The tangent elasticity matrix is used to improve the convergence of the proposed algorithm. In this study, a numerical simulation of the proposed model is achieved by writing subroutines in the FORTRAN language. A numerical example of a hole-in-plate structure under uniaxial stress is analysed. By comparing the results with those obtained by the traditional model, which does not consider the unilateral effect of damage, it is demonstrated that the proposed model is capable of describing the damage-induced unilateral behaviour related to microcracked closure effects. The numerical example validates the effectiveness and realizability of the proposed model.

Analysis of moisture damage susceptibility of semi-rigid base materials based on hydrodynamic pressure erosion test and damage constitutive model

2020 ◽  
Author(s):  
Dong Sha ◽  
Baofeng Pan ◽  
Yiren Sun ◽  
Tiankai Che ◽  
Jiale Lu
Keyword(s):  
Damage Mechanics ◽  
Damage Model ◽  
Hydrodynamic Pressure ◽  
Damage Mechanism ◽  
Moisture Damage ◽  
Rigid Base ◽  
Wheel Load ◽  
Damage Models ◽  
Base Materials ◽  
Erosion Test

The hydrodynamic erosion generated by the pumping action of the wheel load during rain and snow is the main cause of the semi-rigid base failure. Unfortunately, however, very few experimental methods and damage models can reasonably describe and predict the moisture damage performance of semi-rigid base materials under the pumping action. To address this issue, a hydrodynamic pressure erosion test was conducted firstly. Then, the compressive test was performed on the eroded specimens to evaluate the damage mechanism of semi-rigid base materials subjected to hydrodynamic erosion. Finally, a moisture-induced damage model that is applicable to the semi-rigid base materials was established by the concept of damage mechanics. The results indicated that the presented damage model encapsulates the complex behavior of the semi-rigid base materials under the hydrodynamic pressure and provides a more rational method for predicting the moisture damage performance of semi-rigid base materials.

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