A constitutive model for geosynthetic interfaces considering nonlinear softening behavior

2022 ◽  
Vol 143 ◽  
pp. 104633
Author(s):  
Ji-Yun Chang ◽  
Shi-Jin Feng
Keyword(s):  
Constitutive Model ◽  
Softening Behavior

A Constitutive Model of Sandstone Considering the Post Peak Behavior

2017 ◽  
Vol 35 (1) ◽  
pp. 13-25 ◽  
Author(s):  
F. S. Jeng ◽  
M. C. Weng ◽  
F. H. Yeh ◽  
Y. H. Yang ◽  
T. H. Huang
Keyword(s):  
Constitutive Model ◽  
Nonlinear Elasticity ◽  
Strain Curve ◽  
Shear Loading ◽  
Triaxial Tests ◽  
Flow Rule ◽  
Plastic Behavior ◽  
Softening Behavior ◽  
Proposed Model ◽  
Confining Pressures

AbstractIn rock engineering, evaluating the post-peak strength and deformation of rock is necessary. To explore the elasto-plastic behavior of sandstone in the post-peak stage, a series of strain-controlled triaxial tests were conducted under different confining pressures. According to the post-peak characteristics, a constitutive model based on nonlinear elasticity and generalized plasticity is proposed. This proposed model is characterized by the following features: (1) Nonlinear elasticity is observed under hydrostatic and shear loading; (2) the associated flow rule is followed; (3) substantial plastic deformation occurs during shear loading; and (4) post-peak softening behavior is accurately predicted. This model requires twelve material parameters, three for elasticity and nine for plasticity. The proposed model was validated by comparing the triaxial test results of Mushan sandstone at different hydrostatic pressures under dry and saturated conditions. In addition, the model is versatile; it can simulate the deformational behavior of two other sandstones. In summary, the proposed model can reasonably predict the complete stress–strain curve of sandstone.

Constitutive Model of Strain Softening for Soft Rock

2011 ◽  
Vol 250-253 ◽  
pp. 1932-1935
Author(s):  
Song Li ◽  
Hong Jian Liao ◽  
Hang Zhou Li
Keyword(s):  
Constitutive Model ◽  
Strain Softening ◽  
Three Dimensional ◽  
Soft Rock ◽  
Unified Strength Theory ◽  
Softening Behavior ◽  
Proposed Model ◽  
Deviatoric Plane ◽  
Modified Equation ◽  
Rock Specimens

This paper aims to study the strain softening behavior of soft rock. A modified equation of unified strength theory is proposed that is convenient to be applied in geotechnical engineering where compression is customarily taken as positive. And also the limit line on deviatoric plane of this modified equation is derived and introduced into the three dimensional (3D) elastic viscoplastic constitutive model of Yin and Graham. Parameters of the model are determined from experiments of the diatom soft rock specimens. Numerical simulations are performed to compare the strain softening behavior predicted in this paper and triaxial experimental results. Simulation results show that the proposed model can accurately describe the strain softening of soft rock.

STUDY ON SOFTENING CONSTITUTIVE MODEL OF SOFT ROCK USING STRAIN SPACE BASED UNIFIED STRENGTH THEORY

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5375-5380 ◽  
Author(s):  
LI SONG ◽  
CHONGDU CHO ◽  
SHENG LU ◽  
HONGJIAN LIAO
Keyword(s):  
Constitutive Model ◽  
Constitutive Equations ◽  
Strain Softening ◽  
Soft Rock ◽  
Elastoplastic Strain ◽  
Strength Theory ◽  
Unified Strength Theory ◽  
Softening Behavior ◽  
Simulation Results ◽  
Strain Space

This study attempts to modify the unified strength theory by considering compression as a positive load in geotechnical engineering. It also aims to establish a unified elastoplastic strain softening constitutive model which can accurately describe the strain softening behavior of one kind of soft rocks distributed in Japan. The hardening function parameters of the unified elastoplastic strain softening constitutive model are determined from experiments. In addition, numerical simulations of this model are performed to compare the pre-peak, post-peak and the residual strengths of soft rock predicted by this study and experimental results. Simulation results demonstrated that the proposed constitutive equations in strain space can well describe the softening behavior and accurately predict the peak and residual strengths of soft rock. While the proposed equation is applicative for normally consolidated state and overconsolidated state according to the simulation results.

Study on constitutive model and dynamic recrystallization softening behavior of AZ80A magnesium alloy

2019 ◽  
Vol 6 (12) ◽  
pp. 126576
Author(s):  
X W Duan ◽  
J J Liu ◽  
L L Liu ◽  
B Gong ◽  
P Li ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Constitutive Model ◽  
Dynamic Recrystallization ◽  
Softening Behavior

scholarly journals Material Modeling of PMMA Film for Hot Embossing Process

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3398
Author(s):  
Dongwon Yun ◽  
Jong-Bong Kim
Keyword(s):  
Constitutive Model ◽  
Process Condition ◽  
Hot Embossing ◽  
Pmma Film ◽  
Arbitrary Lagrangian Eulerian ◽  
Softening Behavior ◽  
User Subroutine ◽  
Flexible Film ◽  
Precise Analysis ◽  
Fine Pattern

This study provides an analysis of the hot embossing process with poly methyl methacrylate (PMMA) film. The hot embossing process engraves a fine pattern on a flexible film using a stamp, applied heat and pressure. As the quality of the embossing pattern varies according to various process variables, the mechanism of making the embossed shape is complicated and difficult to analyze. Therefore, analysis takes much time and cost because it usually has to perform a lot of experiments to find an appropriate process condition. In this paper, the hot embossing process was analyzed using a computational analysis method to quickly find the optimal process. To do this, we analyzed the embossing phenomenon using the finite element method (FEM) and arbitrary Lagrangian–Eulerian (ALE) re-mesh technique. For this purpose, we developed a constitutive model considering the strain, strain rate, temperature-dependent stress and softening of the flexible film. Work hardening, strain softening, and temperature-softening behavior of PMMA materials were well described by the proposed method. The developed constitutive model were applied in the embossing analysis via user-subroutine. This proposed method allowed a precise analysis of the phenomenon of film change during the hot embossing process.

scholarly journals Influence of Deformation Conditions on the Critical Damage Factor of AZ31 Magnesium Alloy

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Li-juan Pang ◽  
Xin Shang ◽  
Xuefeng Zhang
Keyword(s):  
Magnesium Alloy ◽  
Constitutive Model ◽  
Strain Rate ◽  
Outer Edge ◽  
Az31 Magnesium Alloy ◽  
Damage Factor ◽  
Finite Element Program ◽  
Softening Behavior ◽  
Element Program ◽  
Critical Damage

The influence of deformation conditions on the critical damage factor of AZ31 magnesium alloy was analyzed in this paper. Physical experiments and numerical simulation were used to study the critical damage factor. Compression test was carried out using a Gleeble 1500 device at temperatures between 250°C and 400°C, as well as strain rates from 0.01 s−1 to 1 s−1. True stress-strain curves of samples were obtained. Based on experimental data, an Arrhenius constitutive model was constructed. Material performance parameters and constitutive model were inputted into the finite element program DEFORM. Simulation results show that the maximum damage appears on the outer edge of the upsetting drum, and damage softening behavior is more sensitive to strain rate. According to the concept of damage sensitive rate, its values were computed. The intersection of line fitted and horizontal axis was obtained in the fracture step, and its relative maximum damage value was as the critical damage factor. The distribution of the critical damage value shows that it is not a constant but fluctuates within the range of 0.1445–0.3759, and it is more sensitive to strain rate compared with temperature.

Analytical solution for shear bands in cold-rolled 1018 steel

2012 ◽  
Vol 20 (4-6) ◽  
pp. 89-102 ◽  
Author(s):  
George Z. Voyiadjis ◽  
Amin H. Almasri ◽  
Danial Faghihi ◽  
Anthony N. Palazotto
Keyword(s):  
Constitutive Model ◽  
Shear Banding ◽  
Shear Bands ◽  
Material Model ◽  
Adiabatic Shear ◽  
Adiabatic Shear Banding ◽  
Softening Behavior ◽  
Dynamic Loadings ◽  
Cold Rolled ◽  
Selection Of

AbstractCold-rolled 1018 (CR-1018) carbon steel has been well known for its susceptibility to adiabatic shear banding under dynamic loadings. Analysis of these localizations highly depends on the selection of the constitutive model. To deal with this issue, a constitutive model that takes temperature and strain rate effect into account is proposed. The model is motivated by two physical-based models: the Zerilli and Armstrong and the Voyiadjis and Abed models. This material model, however, incorporates a simple softening term that is capable of simulating the softening behavior of CR-1018 steel. Instability, localization, and evolution of adiabatic shear bands are discussed and presented graphically. In addition, the effect of hydrostatic pressure is illustrated.

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