Prediction of Stress Relaxation Behavior of 2.25Cr-1Mo-0.25V Steel Based on Continuum Damage Mechanics

2014 ◽  
Author(s):  
Yu Zhou ◽  
Xuedong Chen ◽  
Zhichao Fan ◽  
Yichun Han
Keyword(s):  
Stress Relaxation ◽  
Constitutive Model ◽  
Damage Mechanics ◽  
Least Square ◽  
Preliminary Evaluation ◽  
Square Function ◽  
Material Constants ◽  
Highly Nonlinear ◽  
Damage Constitutive Model ◽  
Functional Features

The functional features of the CDM-based damage constitutive model for stress relaxation which has been recently proposed were analyzed. Due to the highly nonlinear hyperbolic sine function adopted in the function and the large difference in the orders of magnitude among the material constants, an efficient genetic algorithm based optimization scheme was applied to obtain the global minima for the least square function. In addition, a procedure for the preliminary evaluation of material constants in the model was developed to better converging to the minima. The user-defined subroutine implementing the damage constitutive model was developed. It is validated that the predicted result provided by the developed ANSYS program agrees well with the experimental data of the stress relaxation for ferritic steels, providing preliminary results for the prediction of reheat cracking.

A Physically Based Damage Constitutive Model for Stress Relaxation

2014 ◽  
Author(s):  
Yu Zhou ◽  
Xuedong Chen ◽  
Zhichao Fan ◽  
Yichun Han
Keyword(s):  
Stress Relaxation ◽  
Constitutive Model ◽  
Damage Mechanics ◽  
Model Comparison ◽  
Continuum Damage Mechanics ◽  
Reheat Cracking ◽  
Physically Based ◽  
Damage Constitutive Model ◽  
Evolution Behavior ◽  
The Continuum

A damage constitutive model for stress relaxation was proposed based on the continuum damage mechanics theory, in terms of the characteristics of damage induced by stress relaxation which is associated with reheat cracking. The effects of strain hardening and the precipitation and growth of carbides on the stress evolution behavior were considered in the present model. To validate the accuracy of the constitutive model, comparison of the predicted result provided by the model and the experimental data of stress relaxation for 2.25Cr-1Mo-0.25V ferritic steel was made. It is shown that the damage constitutive model can be used to predict the stress relaxation behavior and reheat cracking further for low alloy ferritic steels.

scholarly journals Statistical Damage Constitutive Model for Cemented Sand considering the Residual Strength and Initial Compaction Phase

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Cai Tan ◽  
Ming-dao Yuan ◽  
Yong-sheng Shi ◽  
Bing-sheng Zhou ◽  
Hao Li
Keyword(s):  
Constitutive Model ◽  
Residual Strength ◽  
Damage Mechanics ◽  
Triaxial Compression ◽  
Triaxial Stress ◽  
Cemented Sand ◽  
Damage Constitutive Model ◽  
Statistical Damage Constitutive Model ◽  
Initial Compaction ◽  
Statistical Damage

Based on continuum damage mechanics and the assumption of volume invariance, a damage constitutive model of cemented sand under triaxial stress was established while considering residual strength. Statistical theory was then introduced into this model. Assuming that the microunit strength of cemented sand obeys a Weibull random distribution, an expression of microunit strength based on the Mohr–Coulomb criterion was derived. Additionally, a damage evolution equation and a statistical damage constitutive model of cemented sand under triaxial stress were established. In order to consider the nonlinear deformation and volume change in the initial pore compaction stage, the critical point reflecting the completion of the initial compaction stage was determined. This was done by applying the volume invariance assumption to the linear portion of the stress and strain curve and performing a coordinate transformation. The nonlinearity of the initial compaction stage was fitted by a quadratic function. A triaxial compression test of cemented sand was then carried out to verify this proposed method. The results show that the calculated values by the damage constitutive model fit well with the actual experimental values and that the calculated results can reflect the stress softening, residual strength, and initial compaction characteristics of cemented sand, which shows the rationality and feasibility of the model.

Study on Elastic-Plastic Damage Constitutive Model of Frozen Soil Based on Energy Dissipation Theory

2013 ◽  
Vol 423-426 ◽  
pp. 1187-1192 ◽  
Author(s):  
Zhi Min Li ◽  
Tao Liu ◽  
Zhi Li Cui
Keyword(s):  
Energy Dissipation ◽  
Constitutive Model ◽  
Damage Mechanics ◽  
Yield Criterion ◽  
Dissipation Function ◽  
Frozen Soil ◽  
Elastic Plastic ◽  
Plastic Damage ◽  
Plastic Dissipation ◽  
Damage Constitutive Model

Starting from the thermodynamics, model of frozen soil is studied by energy dissipation theory and the inside and outside the state variables is given under isothermal conditions. Damage of frozen soil is re-flecked by effective stress and damage tensor in Damage Mechanics. Dissipation function is in form of plastic dissipation function (DP yield criterion) and the damage dissipation function. And plastic dissipation function is coupled of the damage variable. Through the elastic-plastic and damage evolution, frozen soil incremental elastic-plastic damage constitutive model is made. And finite element scheme is given.

scholarly journals Investigation on the Nonlinear Strength Properties and Damage Statistical Constitutive Model for Frozen Sandy Soils

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
De Zhang ◽  
Enlong Liu ◽  
Xingyan Liu ◽  
Ge Zhang ◽  
Xiao Yin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Constitutive Model ◽  
Damage Mechanics ◽  
Sandy Soils ◽  
Continuum Damage Mechanics ◽  
Strength Properties ◽  
Principal Stresses ◽  
Confining Pressures ◽  
Damage Constitutive Model ◽  
Frozen Sandy Soil

There are many flaws, such as fissures, cavities, and inclusions, in geomaterials, which make their mechanical properties with great randomness and uncertainty. Upon loading, the soil structure gradually losses the bearing capacity due to the transformation from microdefects to macroscopic breakage bands. Based upon the experimental data of frozen sandy soils, a new nonlinear strength equation between the first and third principal stresses was proposed, and then the nonlinear strength properties for frozen sandy soils in σ-τ plane were analyzed. In addition, by assuming that the microstrength of frozen sandy soil obeys the Weibull distribution function, a statistical damage constitutive model was established based upon the framework of continuum damage mechanics (CDM), with few parameters and a high accuracy. Compared with experimental data, the new model can well grasp the nonlinear strength properties and simulate the stress-strain relationships under different confining pressures for frozen sandy soils.

Three-dimensional elastic-plastic damage constitutive model of wood

Holzforschung ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Lipeng Zhang ◽  
Qifang Xie ◽  
Baozhuang Zhang ◽  
Long Wang ◽  
Jitao Yao
Keyword(s):  
Constitutive Model ◽  
Damage Mechanics ◽  
Euler Method ◽  
Isotropic Hardening ◽  
Damage Initiation ◽  
Elastic Plastic ◽  
Plastic Damage ◽  
Backward Euler ◽  
Tension And Compression ◽  
Damage Constitutive Model

AbstractA 3D combined elastic-plastic damage constitutive model for wood is proposed within the theoretical framework of classical plasticity and continuum damage mechanics (CDM). The model is able to describe the various behavior of wood under loading, including the orthotropic elasticity, strengths inequality under tension and compression in each orthotropic direction, ductile softening under longitudinal compression, brittle failure under transverse tension, and parallel shearing, densification hardening under transverse compression. Hoffman criterion and a set of eight separate failure criteria were used to define wood yielding and damage initiation, respectively. Isotropic hardening was assumed after yielding and defined by an exponential type function. The constitutive model was implicitly discretized using backward Euler method, solved through the return mapping algorithm and implemented into ABAQUS through the user-defined material subroutine (UMAT). The proposed model was firstly verified by material property tests considering different stress states: monotonic and repeated tension and compression (in both parallel and perpendicular-to-grain directions), parallel-to-grain shearing, and the interactions between perpendicular-to-grain compression/tension and parallel-to-grain shearing, etc. Mechanical behavior of typical structural elements was further simulated to validate the proposed constitutive model.

scholarly journals Three dimensional statistical damage constitutive model of rock based on Griffith strength criterion

2021 ◽  
Author(s):  
Song Chen ◽  
Xiuling Cao ◽  
Zhao Yang
Keyword(s):  
Constitutive Model ◽  
Principal Stress ◽  
Damage Mechanics ◽  
Brittle Materials ◽  
Strength Criterion ◽  
Intermediate Principal Stress ◽  
True Triaxial ◽  
Damage Constitutive Model ◽  
Two Parameters ◽  
The Relationship

Abstract According to the damage mechanics theory and Lemaitre strain equivalence theory, because most rock materials are brittle materials, Griffith strength criterion has good applicability to describe the fracture failure of brittle materials from the perspective of energy. Using a new method to describe the rock micro-element strength based on Griffith strength criterion, and assuming the micro-element strength obeys the Weibull distribution, a true triaxial constitutive model of damage softening reflecting the whole process of rock failure is established. On this basis, the influence of the two parameters in the model on the curve of the constitutive model is analyzed, and the relationship between the two parameters and the intermediate principal stress in the model is established, and the model is revised reasonably. Finally, a true triaxial damage constitutive model of rock is established. The results are in good agreement with the experimental curve, which verifies its validity and rationality. At the same time, the relationship between the damage evolution and the strain and stress is discussed, and the influence of the size of the intermediate principal stress on the relationship is analyzed in detail.

Constitutive Description for Drawing Limit of Magnesium Alloy Tube Based on Continuum Damage Mechanics

2009 ◽  
Vol 610-613 ◽  
pp. 951-954 ◽  
Author(s):  
Ying Tong ◽  
Guo Zheng Quan ◽  
Bin Chen
Keyword(s):  
Magnesium Alloy ◽  
Constitutive Model ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Plastic Behavior ◽  
Continuum Damage ◽  
Rigid Plastic ◽  
Alloy Tube ◽  
Limit Graph ◽  
Damage Constitutive Model

The elasto-plastic behavior and the drawing limit of a kind of magnesium alloy tube were investigated based on the foundational theories of the larger deformation of material and continuum damage constitutive model. The corresponding finite element numerical algorithm was developed based on the constitutive model. The non-mandrel drawing limit graph according to the diameter at different tube thickness of an AZ31B tube with diameter 10mm at 250°C and drawing velocity 100mm/s was achieved, and safe & unsafe area got partitioned. The maximum damage value was evaluated to be 0.324 according to height reduction ratio limit and rigid-plastic FE analysis.

scholarly journals A Damage Constitutive Model of Rock under Hydrochemical Cyclic Invasion

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Lunan Sun ◽  
Yu Zhang ◽  
Zhe Qin ◽  
Tengfei Wang ◽  
Sheng Zhang
Keyword(s):  
Elastic Modulus ◽  
Constitutive Model ◽  
Damage Mechanics ◽  
Rock Strength ◽  
Strength Distribution ◽  
Peak Strength ◽  
Compression Tests ◽  
Cycle Times ◽  
Circulating Water ◽  
Damage Constitutive Model

In order to analyze the stability of water-related materials, the deterioration and damage of rock strength due to circulating water intrusion in an open tailings pond were studied. Uniaxial compression tests were carried out for rocks under different hydrochemical environments and varying numbers of invasion cycles. Results show that, with increasing number of cycle times, rock peak strength and elastic modulus gradually decrease and the acidity and alkalinity of the soaking solution also degrades rock strength. The curve of the number of cycles, acidity, alkalinity, peak strength, and elastic modulus is fit numerically. Based on the principle of damage mechanics, a hydraulic-chemistry-mechanics (HCM) coupling damage variable is defined. Based on the theory of microbody strength distribution, the constitutive equation for rock damage under the coupled effect of water chemistry and cyclic water invasion is established. The results verify the validity of the established damage constitutive model.

scholarly journals Descriptions of the mechanical behaviour of the Xigeda formation in Zhaizi village, Yunnan Province, China

2021 ◽  
Author(s):  
Xiaodong Fu ◽  
Yuxiang Du ◽  
Qian Sheng
Keyword(s):  
Constitutive Model ◽  
Water Content ◽  
Mechanical Behaviour ◽  
Damage Mechanics ◽  
Soft Rock ◽  
Friction Angle ◽  
Triaxial Tests ◽  
Engineering Practice ◽  
Jinsha River ◽  
Damage Constitutive Model

Abstract The Xigeda formation is a set of Cenozoic lacustrine semi-rock discontinuously distributed in Southwest China. As a typical hard soil or soft/weak rock, the Xigeda formation causes problems when encountered in engineering practice due to its previously unknown mechanical behaviour. Typical samples taken from Zhaizi village along the Jinsha River have been studied. Influences of both the water content and the confining pressure on strength indices of the Xigeda formation were investigated by performing triaxial tests, and the statistical correlations between the shear strength index and the water content of the Xigeda formation, and its soft rock and soil are analysed. By introducing the tenets of the theory of damage mechanics, a damage constitutive model for the deformation of the Xigeda formation and the influence of the water content thereon was established. The results show that: (a) the peak strength, the cohesion and the friction angle decrease linearly with increasing water content; (b) the sensitivity of cohesion to water content is ranked (in ascending order) as: soft rock, the Xigeda formation, then soil, and the sensitivity of friction angle to water content is ranked (in ascending order) as: soil, the Xigeda formation, then soft rock; (c) the damage constitutive model requires few input variables, has a simple form, and can reflect the deformation and strength characteristics of the Xigeda formation under different confining pressures and water contents. The results provide a mechanism with which to understand and model (for both theoretical study and engineering application) the Xigeda formation.

A Developed Damage Constitutive Model for Circular Steel Tubes of Reticulated Shells

2020 ◽  
Vol 20 (09) ◽  
pp. 2050106
Author(s):  
Sheng He ◽  
Haosen Wang ◽  
Stéphane P. A. Bordas ◽  
Peng Yu
Keyword(s):  
Constitutive Model ◽  
Damage Mechanics ◽  
Dynamic Instability ◽  
Damage Model ◽  
Nonlinear Dynamic Analysis ◽  
Continuum Damage Mechanics ◽  
Steel Tubes ◽  
Mapping Algorithm ◽  
Comparison Results ◽  
Damage Constitutive Model

The aim of this paper is that the precise description of damage behavior is crucial to well catch the mechanical behavior of structures in the dynamic numerical simulation, and address the issue on the coupled plastic-damage constitutive model for circular steel tubes of reticulated shells under severe earthquake. Continuum Damage Mechanics (CDM) constitutive model established by Lemaitre is reviewed at the beginning. Then, an improved damage model for circular steel tubes of reticulated shells is developed based on Lemaitre’s model by replacing the original damage evolution law with a new one suitable for circular steel tubes. In addition, we introduce the stress update process. In this procedure, the well-known operator split strategy, which leads to the standard elastic predictor/return mapping algorithm, is adopted to solve the evolution problem of the improved model. Exploiting user-defined material subroutine, the implementation of the model is achieved within software ANSYS using BEAM189 element. Finally, the dynamic response of reticulated shells under severe earthquake are numerically simulated with the proposed model and with the conventional Prandtl-Reuss model, respectively. The comparison results show that the consideration of material damage accumulation, on the one hand, may change the failure mode of reticulated shells from dynamic instability to strength failure; on the other, may reduce the dynamic ultimate load obviously. This consideration should be taken into account when conducting nonlinear dynamic analysis of reticulated shells.

Sign in / Sign up

Export Citation Format

Share Document