Stress Sensitivity of Damage Evolution Equation and Mesh-Dependence in Local Approach.

1995 ◽  
Vol 44 (507) ◽  
pp. 1417-1422 ◽  
Author(s):  
Yan LIU ◽  
Sumio MURAKAMI ◽  
Tetsuya YAMADA ◽  
Yasushi KANAGAWA
Keyword(s):  
Evolution Equation ◽  
Damage Evolution ◽  
Stress Sensitivity ◽  
Local Approach ◽  
Damage Evolution Equation

Damage Analysis of Concrete Subjected to Freeze-Thaw Cycles and Chloride Ion Erosion

2011 ◽  
Vol 488-489 ◽  
pp. 464-467
Author(s):  
Ji Ze Mao ◽  
Zhi Yuan Zhang ◽  
Zong Min Liu ◽  
Chao Sun
Keyword(s):  
Constitutive Equation ◽  
Evolution Equation ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Chloride Ion ◽  
Offshore Structures ◽  
Damage Evolution Equation ◽  
Freeze Thaw ◽  
Concrete Materials ◽  
Ion Erosion

With the development of damage mechanics, many researchers have used it to analyze the constitutive equation of concrete. Since the special environment in the cold marine regions, the offshore structures are common to subject to the comprehensive effects of freeze-thaw action and chloride erosion. This might cause concrete materials degradation and reduce the mechanical performance of concrete seriously. In this paper, based on the analysis and mechanical experiments of concrete materials under the comprehensive effects of freeze-thaw action and chloride ion erosion, the damage evolution equation of concrete elastic modulus along with the freeze-thaw cycles and chloride ion contents was established. The effects of chloride ion were investigated during the process of concrete degradation. According to the damage evolution equation, a new constitutive equation of concrete under freeze-thaw action and chloride erosion was established. And then, by means of the element simulation analysis of concrete beams when subjected to the comprehensive actions, the feasibility and applicability of the equation was examined and discussed. In this equation, both the freeze-thaw action and chloride ion erosion were considered together. It will be more suitable for analyzing the durability of concrete structures in the real cold marine regions. It will also provide some references for concrete constitutive theory.

Study On the Damage Evolution Equation of Rockburst

2008 ◽  
Vol 33-37 ◽  
pp. 663-668
Author(s):  
Quan Sheng Liu ◽  
Bin Liu ◽  
Wei Gao
Keyword(s):  
Energy Dissipation ◽  
Evolution Equation ◽  
Damage Evolution ◽  
Minimum Energy ◽  
Strength Criterion ◽  
Internal Variable ◽  
Total Strength ◽  
Damage Evolution Equation ◽  
Traditional Research ◽  
Minimum Energy Dissipation

This paper introduces the principle of minimum energy dissipation and its general procedures to establish development equation of internal variable. With the accepted viewpoint that the damage is only mechanics of energy dissipation during the rockburst and utilizing the total strength criterion based on released strain energy, the general damage evolution equation is deduced. Compared with the traditional research method of damage evolution equation, this method has universal and objective characteristics.

Damage Evolution Equation of AZ31B Magnesium Alloy during Superplastic Deformation

2009 ◽  
Vol 610-613 ◽  
pp. 831-837
Author(s):  
Mei Juan Song ◽  
Ling Yun Wang ◽  
Rao Chuan Liu ◽  
Zhi Xiang Wang
Keyword(s):  
Quantitative Analysis ◽  
Evolution Equation ◽  
Superplastic Deformation ◽  
Damage Evolution ◽  
Volume Fraction ◽  
Tensile Tests ◽  
Critical Value ◽  
Cavity Volume ◽  
Characteristic Parameters ◽  
Damage Evolution Equation

After superplastic tensile tests and quantitative analysis of cavity volume fraction, the damage evolution equation based on the law of the micro-damage evolution and statistical mechanics was derived out. The characteristic parameters of damage evolvement and critical value of damage variables are achieved from the experiments.

Damage-coupled FLD of Sheet Metals for Warm Forming and Nonproportional Loading

2011 ◽  
Vol 20 (8) ◽  
pp. 1243-1262 ◽  
Author(s):  
M. Jie ◽  
C. L. Chow ◽  
X. Wu
Keyword(s):  
Evolution Equation ◽  
Damage Evolution ◽  
Strain Softening ◽  
Forming Limit ◽  
Sheet Metals ◽  
Nonproportional Loading ◽  
Damage Evolution Equation ◽  
Localized Necking ◽  
Loading Paths ◽  
Necking Criterion

A method of forming limit prediction for sheet metals at high temperatures and under nonproportional loading is presented. The method takes into account the strain-softening behaviors of the material at elevated temperatures. A localized necking criterion based on an isotropic damage-coupled acoustic tensor is developed and employed to determine the forming limits of strain-softening materials. The damage evolution equation is developed within the thermo-mechanical framework. A closed-form expression of the forming limit strains is derived by coupling the damage evolution equation into the localized necking criterion. A computer program, incorporating the incremental theory of plasticity, the damage evolution equation and the localized necking criterion, is developed to compute the forming limit strains under several nonproportional loading paths. A series of the uniaxial tensile tests is performed to measure the relevant mechanical properties of AA6061 at the elevated temperature of 450°C. The material damage variables are determined from the measured elastic modulii from a series of loading and unloading paths. The damage evolution equation of AA6061 at 450°C is formulated based on the test data. The computed limit strains are compared with the test results under various loading paths and a good agreement is observed. It is found that the critical damage value is independent on the stress states and loading paths. It may be concluded that the application of the material damage as a reliable criterion of localized necking including the nonproportional loading cases.

A Nonlinear Viscoelastic and Micromechanical Damage Constitutive Model for Solid Propellant

2013 ◽  
Vol 750-752 ◽  
pp. 2196-2199
Author(s):  
Zhi Xu Gu ◽  
Jian Zheng ◽  
Wei Peng ◽  
Xi Nan Tang ◽  
Jun Hui Yin
Keyword(s):  
Constitutive Model ◽  
Evolution Equation ◽  
Damage Evolution ◽  
Solid Propellant ◽  
Damage Evolution Equation ◽  
Nonlinear Viscoelastic ◽  
Tension Tests ◽  
Composite Solid Propellant ◽  
Damage Process ◽  
Viscoelastic Constitutive Model

This paper studies the damage process induced by dewetting microcracks in composite solid propellant. A nonlinear viscoelastic constitutive model for composite soild propellant is presented. The damage variable D is derived from the microcrack system and is function of microcrack size density. The damage evolution equation is determinded by the extending of microcrack. Form the proposed model of microrack evolution process, an explicit form of damage evolution equation which is a function of stress field is given. The cracking event N and the new crack surface area damage ΔA formed by microcrack extension are defined. Material constants are determinded by acoustic emission tests. The rationality of our model has been confirmed by tension tests.

A Multiaxial Damage Statistic Constitutive Model for Concrete

2012 ◽  
Vol 166-169 ◽  
pp. 56-59
Author(s):  
Shan Suo Zheng ◽  
Wen Yong Li ◽  
Qing Lin Tao ◽  
Yu Fan
Keyword(s):  
Numerical Simulation ◽  
Quantitative Analysis ◽  
Stress State ◽  
Constitutive Equation ◽  
Evolution Equation ◽  
Damage Evolution ◽  
Equivalent Strain ◽  
Triaxial Stress State ◽  
Decoupling Method ◽  
Damage Evolution Equation

In order to apply the uniaxial damage evolution equation that established with the variable of strain to the multiaxial damage quantitative analysis, this paper bases on the Hsieh-Tang-Chen four-parameter failure criterion and adopts the way of making the triaxial equivalent strain combining with the uniaxial damage evolution equation to analyze and deduce the uniaxial damage evolution equation of SRHSHPC, and which is expanded to multiaxial condition as well. A function considered triaxial stress state and a related correction value are suggested, then, improving the damage evolution equation from triaxial to multiaxial form, finally proposing the multiaxial damage statistic constitutive equation for concrete, taking numerical simulation with the complete decoupling method and the result shows that the model is effective.

The Effect of Lack-of-Fusion Porosity on Fatigue Behavior of Additive Manufactured Titanium Alloy

2016 ◽  
Vol 723 ◽  
pp. 44-50
Author(s):  
Hua Liang Wan ◽  
Qi Zhi Wang ◽  
Hui Xing Lin
Keyword(s):  
Experimental Data ◽  
Evolution Equation ◽  
Damage Evolution ◽  
Present Method ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Fatigue Performance ◽  
Additive Manufacture ◽  
Damage Evolution Equation ◽  
Lack Of Fusion

As we know, the fatigue performance of AM materials is highly associated with the microstructure. The fatigue performance of additive manufacture alloy materials of Ti-6Al-4V is investigated in this study. Considering the hysteresis energy, a damage evolution equation has been advanced. The material parameters in damage evolution equation are obtained with fatigue experimental data. A homogenizing model with reflecting microstructures is established. Two types of defects, gas porosity and lack-of-fusion porosity, are discussed. The mean fatigue crack initiation lives of additive manufactured Ti6Al4V with different orientations are predicted by the present method. The computational results are agreement well with the experimental data. The effect of lack-of-fusion porosity density on the fatigue performance of AM materials is studied. The fatigue lives of AM materials with different lack-of-fusion porosity size are evaluated. This present method represents the effect of the microdefect on the fatigue performance, with the effect of anisotropic damage and strain.

Sign in / Sign up

Export Citation Format

Share Document