scholarly journals The improved unified constitutive model: a fine-tuned material model tailored for more challenging geotechnical conditions

2017 ◽  
Author(s):  
Abouzar Vakili
Keyword(s):  
Constitutive Model ◽  
Material Model

A Constitutive Model for Jointed Rock Mass With Orthogonal Sets of Joints

1989 ◽  
Vol 56 (1) ◽  
pp. 25-32 ◽  
Author(s):  
E. P. Chen
Keyword(s):  
Constitutive Model ◽  
Material Model ◽  
Jointed Rock ◽  
Rate Equations ◽  
Strain Partitioning ◽  
Additional Material ◽  
The Subject ◽  
Nonlinear Normal ◽  
Elastic Rock ◽  
The Continuum

The development and numerical implementation of a constitutive model for jointed rock media is the subject of investigation in this paper. The constitutive model is based on the continuum assumption of strain-partitioning among the elastic rock matrix and joint sets with nonlinear normal and shear responses. Rate equations for the stress-strain response of the jointed media have been formulated. A numerical incremental solution scheme to these equations has been developed. It has been implemented into the finite element code JAC as an additional material model. Several sample problems have been solved for demonstration purposes. Interpretation and discussion of these results are presented.

Indentation Tests Based on Gelatin Phantom

2013 ◽  
Vol 483 ◽  
pp. 386-390
Author(s):  
Lei Song ◽  
Tong Su ◽  
Li Ying Gao ◽  
Qin He Zhang
Keyword(s):  
Constitutive Model ◽  
Least Squares Method ◽  
Fem Simulation ◽  
Indentation Test ◽  
Target Material ◽  
Fem Analysis ◽  
Material Model ◽  
Fem Model ◽  
Indentation Tests ◽  
Viscoelastic Characteristics

In order to improve the accuracy of biopsy, an accurate FEM model is quite essential. To get the coefficients of the puncture target material which will be used in the Abaqus FEM analysis, the paper performed indentation test on gelatin phantom which is more stable than normal biological tissue. The Neo-Hookean and the improved Kelvin constitutive model were used to describe the mechanical properties of gelatin phantom demonstrated in the tests, including the hyperelastic and viscoelastic characteristics, then least squares method was used to fit the experimental data, finally the parameters of each constitutive model were achieved, which will be used to establish the material model in the further Abaqus FEM simulation.

scholarly journals Computational Modelling of Fracture Propagation in Rocks Using a Coupled Elastic-Plasticity-Damage Model

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Isa Kolo ◽  
Rashid K. Abu Al-Rub ◽  
Rita L. Sousa
Keyword(s):  
Constitutive Model ◽  
Damage Model ◽  
Computational Modelling ◽  
Fracture Propagation ◽  
Material Model ◽  
Model Predictions ◽  
Tension And Compression ◽  
Damage Constitutive Model ◽  
Ak Model ◽  
Spatially Varying

A coupled elastic-plasticity-damage constitutive model, AK Model, is applied to predict fracture propagation in rocks. The quasi-brittle material model captures anisotropic effects and the distinct behavior of rocks in tension and compression. Calibration of the constitutive model is realized using experimental data for Carrara marble. Through the Weibull distribution function, heterogeneity effect is captured by spatially varying the elastic properties of the rock. Favorable comparison between model predictions and experiments for single-flawed specimens reveal that the AK Model is reliable and accurate for modelling fracture propagation in rocks.

scholarly journals Identification parameters of material model and large deformation analysis of inflated air-spring shell made of rubber-textile cord composite

2005 ◽  
Vol 27 (2) ◽  
pp. 118-128
Author(s):  
Tran Huu Nam
Keyword(s):  
Constitutive Model ◽  
Least Squares Method ◽  
Strain Energy Function ◽  
Nonlinear Least Squares ◽  
Material Model ◽  
Constitutive Law ◽  
Deformation Analysis ◽  
Air Spring ◽  
Nonlinear Least Squares Method ◽  
Material Constitutive Law

In the paper an orthotropic hyperelastic constitutive model is presented which can be applied to numerical simulation for the response of biological soft tissue and of the nonlinear anisotropic hyperelastic material of the cylindrical air-spring shell used in vibroisolation of driver's seat. The parameters of strain energy function of the proposed constitutive model are fitted to the experimental results by the nonlinear least squares method. The deformation of the inflated cylindrical air-spring shell is calculated by solving the system of five first-order ordinary differential equations with the material constitutive law and proper boundary conditions. Numerical results of principal stretches and deformed profiles of the inflated cylindrical air-spring shell obtained by numerical deformation analysis are compared with experimental ones.

scholarly journals CONSTITUTIVE MODEL FOR TIMBER FRACTURE USED FOR FE SIMULATION OF LVL ARCH

2018 ◽  
Vol 15 ◽  
pp. 109-113 ◽  
Author(s):  
Eliška Šmídová ◽  
Petr Kabele
Keyword(s):  
Constitutive Model ◽  
Shear Fracture ◽  
Material Model ◽  
Compact Tension ◽  
Bending Test ◽  
Yellow Poplar ◽  
Laminated Veneer Lumber ◽  
Four Point Bending ◽  
Element Simulation ◽  
Gt Element

Non-linear finite element simulation of four-point bending test of a small-size arch is described in this paper. The arch of 780mm span is made of Yellow Poplar (<em>Liriodendron tulipifera</em>) laminated veneer lumber (LVL) and it is manufactured with a through crack parallel to fibers in the middle of its crown. 2D homogeneous orthotropic constitutive model of tensile and shear fracture in timber that has been recently developed and implemented into ATENA<sup>®</sup> element software by the authors is used for the numerical calculation. Both standard and compact tension (CT) test results are used for the material model calibration. Results show that the model successfully reproduces the increasing part of the load-displacement response. Furthermore, the model can capture the most distinctive features of the crack pattern.

scholarly journals Identification of the Constitutive Model Parameters by Inverse Optimization Method and Characterization of Hot Deformation Behavior for Ultra-Supercritical Rotor Steel

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1958
Author(s):  
Xuewen Chen ◽  
Yuqing Du ◽  
Kexue Du ◽  
Tingting Lian ◽  
Bingqi Liu ◽  
...  
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Deformation Behavior ◽  
Material Model ◽  
Optimization Method ◽  
Resistant Steel ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Heat Resistant Steel ◽  
Heat Resistant

X12 (X12CrMoWVNbN10-1-1) ferritic heat resistant steel is an important material for the production of new-generation ultra-supercritical generator rotors. Hot compression tests of X12 ferritic heat-resistant steel were performed via a Gleeble-1500D testing machine under temperatures of 1050–1250 °C and strain rates of 0.05–5 s−1. In order to provide material model data for finite element simulations and accurately predict the hot deformation behavior, a reverse optimization method was proposed to construct elevated temperature constitutive models of X12 ferritic heat-resistant steel in this paper, according to the Hansel–Spittel constitutive model. To verify the accuracy of the model, the predicted and experimental values of the constitutive model were compared. The results indicated that the model had a high prediction accuracy. Meanwhile, the correlation coefficient between the experimental value and the predicted value of constitutive model was 0.97833. For further verification of the accuracy of the model, it was implemented in finite element FORGE@ software to simulate the compression tests of different samples under different conditions. Comparing actual displacement–load curves with displacement–load curves acquired through finite element simulations, the results indicated that displacement–load curves predicted by the model were very consistent with actual displacement–load curves, which verified the accuracy of the model. Moreover, to research the optimal processing parameters of the material, hot processing maps were drawn according to the dynamic material model. In terms of microstructure evolution, a characteristic area distribution map of the hot processing map was established. Therefore, the optimal hot forming parameters regions were in the range of 1150–1200 °C/0.05–0.62 s−1 for X12 ferritic heat-resistant steel.

scholarly journals Influence of Constitutive Models and the Choice of the Parameters on FE Simulation of Ti6Al4V Orthogonal Cutting Process for Different Uncut Chip Thicknesses

2021 ◽  
Vol 5 (2) ◽  
pp. 56
Author(s):  
Nithyaraaj Kugalur Palanisamy ◽  
Edouard RiviÈre LorphÈvre ◽  
Pedro-José Arrazola ◽  
François Ducobu
Keyword(s):  
Constitutive Model ◽  
Orthogonal Cutting ◽  
Constitutive Models ◽  
Chip Thickness ◽  
Material Model ◽  
Machining Process ◽  
Uncut Chip Thickness ◽  
Dependent Strain ◽  
Important Input

The constitutive model and its pertinent set of parameters are important input data in finite element modeling to define the behavior of Ti6Al4V during machining process. The present work focusses on comparing different constitutive models and the parameters sets available in literatures and investigating the quality of the predictions when varying uncut chip thickness (40 µm, 60 µm, 100 µm and 280 µm). In addition, temperature-dependent strain hardening factor along with strain softening phenomenon based reconstructed material model is proposed. The results from the numerical simulations are compared with experimental results available in literature. The comparison shows that the force values are highly influenced by constitutive models and the choice of parameters sets, whereas the chip morphologies are mainly influenced by the uncut chip thickness and constitutive models. This work justifies the need for an appropriate set of parameters and constitutive model that replicate the machining behavior of Ti6Al4V alloy for different cutting conditions.

scholarly journals An efficiency comparison of numerical implementation approaches of hyperelastic constitutive model in ABAQUS/Standard

2018 ◽  
Vol 196 ◽  
pp. 01052
Author(s):  
Aleksander Franus ◽  
Łukasz Kowalewski
Keyword(s):  
Constitutive Model ◽  
Contact Problem ◽  
Computational Efficiency ◽  
Energy Function ◽  
Material Model ◽  
Numerical Implementation ◽  
Stored Energy ◽  
Efficiency Comparison ◽  
Consistent Tangent Operator

The main goal of the article is to compare a computational efficiency of different implementation of a hyperelastic material model in the ABAQUS/Standard v. 6.14 [1]. The software offers basically two ways to proceed, namely UMAT and UHYPER user subroutines [2]. The procedures are employed to implement an isotropic, compressible neo-Hookean material model [3]. Corresponding stored-energy function, constitutive equations and the consistent tangent operator are presented. These are essential to program the subroutines. Some theoretical and numerical aspects of different implementation approaches are discussed. As examples, a tube under axial compression and a contact problem of disc are considered. On the basis of obtained results, selected aspects of computational efficiency and quality of solutions are compared.

The Constitutive Equation for Silicon and Its Use in Crystal Growth Modeling

1990 ◽  
Vol 112 (2) ◽  
pp. 183-187 ◽  
Author(s):  
C. T. Tsai ◽  
O. W. Dillon ◽  
R. J. De Angelis
Keyword(s):  
Crystal Growth ◽  
Dislocation Density ◽  
Constitutive Equation ◽  
Constitutive Model ◽  
Material Model ◽  
Internal Variable ◽  
Dislocation Motion ◽  
Silicon Crystals ◽  
Initial Dislocation Density ◽  
Temperature Strain

A stress analysis that describes the crystal growing process requires a material model that is valid over a wide temperature range and includes dislocation motion and multiplication. The stresses developed in the growing process could induce residual stresses, changes in dislocation density and buckling into the growing crystals. The dislocation density is introduced as an internal variable in the constitutive model. The stress-strain and dislocation density-strain characteristics of silicon crystals are discussed as a function of temperature, strain rate, and initial dislocation density.

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