Stochastic finite element analysis of rockfill dam considering spatial variability of dam material porosity

2019 ◽  
Vol 36 (9) ◽  
pp. 2929-2959
Author(s):  
Hui Chen ◽  
Donghai Liu
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Spatial Variability ◽  
Random Field ◽  
Model Parameters ◽  
Mechanical Parameters ◽  
Stochastic Finite Element ◽  
Content Type ◽  
Rockfill Dam ◽  
Stochastic Fem

Purpose The purpose of this study is to develop a stochastic finite element method (FEM) to solve the calculation precision deficiency caused by spatial variability of dam compaction quality. Design/methodology/approach The Choleski decomposition method was applied to generate constraint random field of porosity. Large-scale laboratory triaxial tests were conducted to determine the quantitative relationship between the dam compaction quality and Duncan–Chang constitutive model parameters. Based on this developed relationship, the constraint random fields of the mechanical parameters were generated. The stochastic FEM could be conducted. Findings When the fully random field was simulated without the restriction effect of experimental data on test pits, the spatial variabilities of both displacement and stress results were all overestimated; however, when the stochastic FEM was performed disregarding the correlation between mechanical parameters, the variabilities of vertical displacement and stress results were underestimated and variation pattern for horizontal displacement also changed. In addition, the method could produce results that are closer to the actual situation. Practical implications Although only concrete-faced rockfill dam was tested in the numerical examples, the proposed method is applicable for arbitrary types of rockfill dams. Originality/value The value of this study is that the proposed method allowed for the spatial variability of constitutive model parameters and that the applicability was confirmed by the actual project.

scholarly journals Multiresolution Analysis for Stochastic Finite Element Problems with Wavelet-Based Karhunen-Loève Expansion

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Carsten Proppe
Keyword(s):  
Finite Element ◽  
Random Field ◽  
Spatial Resolution ◽  
Multiresolution Analysis ◽  
Random Parameter ◽  
Wavelet Expansion ◽  
Projection Operators ◽  
Stochastic Finite Element ◽  
Truncation Level

Multiresolution analysis for problems involving random parameter fields is considered. The random field is discretized by a Karhunen-Loève expansion. The eigenfunctions involved in this representation are computed by a wavelet expansion. The wavelet expansion allows to control the spatial resolution of the problem. Fine and coarse scales are defined, and the fine scales are taken into account by projection operators. The influence of the truncation level for the wavelet expansion on the computed reliability is documented.

Finite element simulation of ferromagnetic shape memory alloys using a revised constitutive model

2017 ◽  
Vol 28 (19) ◽  
pp. 2853-2871 ◽  
Author(s):  
Siavash Jafarzadeh ◽  
Mahmoud Kadkhodaei
Keyword(s):  
Finite Element ◽  
Shape Memory Alloy ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Model Parameters ◽  
Ferromagnetic Shape Memory Alloy ◽  
Ferromagnetic Shape Memory Alloys ◽  
Numerical Predictions ◽  
Ferromagnetic Shape Memory

In this article, a previously developed constitutive model for ferromagnetic shape memory alloys is phenomenologically enhanced using experimental observations. A modified phase diagram along with a method for calibration of the required model parameters is further presented. The model is implemented into a user material subroutine to equip commercial finite element software ABAQUS with the capability of simulating magneto-mechanical behaviors of ferromagnetic shape memory alloys. A combined convergence scheme is employed to solve the implicit equations. The proposed model together with the presented numerical solution is shown to be able to study shape memory effect and pseudoelasticity at different constant magnetic fields. The simulated magnetic loading/unloading cycles at different constant stresses are found to be well-fitted to the experimental findings. As a practical application of the ferromagnetic shape memory alloy coupled magneto-mechanical response, a spring actuator (a bias spring serially connected to one ferromagnetic shape memory alloy element) is investigated, and the numerical predictions are shown to be in a good agreement with available experimental results. As a novel case, geometrically graded NiMnGa elements are also introduced and are simulated with the use of this approach.

Bodner-Partom Constitutive Model and Nonlinear Finite Element Analysis

1990 ◽  
Vol 112 (3) ◽  
pp. 287-291 ◽  
Author(s):  
F. A. Kolkailah ◽  
A. J. McPhate
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Plastic Strain ◽  
Constitutive Model ◽  
Finite Element Model ◽  
Numerical Technique ◽  
Element Model ◽  
Material Behavior ◽  
Model Parameters ◽  
Elastic Plastic

In this paper, results from an elastic-plastic finite-element model incorporating the Bodner-Partom model of nonlinear time-dependent material behavior are presented. The parameters in the constitutive model are computed from a leastsquare fit to experimental data obtained from uniaxial stress-strain and creep tests at 650°C. The finite element model of a double-notched specimen is employed to determine the value of the elastic-plastic strain and is compared to experimental data. The constitutive model parameters evaluated in this paper are found to be in good agreement with those obtained by the other investigators. However, the parameters determined by the numerical technique tend to give response that agree with the data better than do graphically determined parameters previously used. The calculated elastic-plastic strain from the model agreed well with the experimental strain.

Linear analysis of parameters in Arrhenius model for Ti-6Al-4V at superplastic forming

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Junzhou Yang ◽  
Jianjun Wu ◽  
Qianwen Zhang ◽  
Yinxiang Ren ◽  
Han Ruolan ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Flow Behavior ◽  
Superplastic Forming ◽  
Tensile Tests ◽  
Model Parameters ◽  
Content Type ◽  
Forming Mechanism ◽  
Good Ability ◽  
Titanium Material ◽  
High Temperature Tensile

Purpose With the discussion on the linear relationship of determined material parameters, this study aims to propose a new method to analyze the deformation mechanism. Design/methodology/approach A modified constitutive model based on the hyperbolic sine Arrhenius equation has been established, which is applied to describe the flow behavior of Ti-6Al-4V alloy during the superplastic forming (SPF). Findings The modified constitutive model in this work has a good ability to describe the flow behavior for Ti-6Al-4V in SPF. Besides, a deformation map of titanium material is obtained based on the parameters. As the supplement, finite element models of high-temperature tensile tests are carried out as the application of the constitutive model. Originality/value The relationship between constitutive model parameters and forming mechanism is established, which is a new angle in rheological behavior research and constitutive model analysis.

Stochastic Finite Element Theory Based on Visco-Plasto Constitution

2013 ◽  
Vol 663 ◽  
pp. 672-675
Author(s):  
Ya Jun Wang ◽  
Yu Hu ◽  
Zheng Zuo ◽  
Xiao Qing Gan ◽  
Zhi Hong Dong
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Boundary Conditions ◽  
Stochastic Theory ◽  
Stochastic Finite Element Method ◽  
Stochastic Finite Element ◽  
Stochastic Fem ◽  
Non Linear ◽  
Element Theory ◽  
Important Character

Most geo-engineering cases have non-linearity. Particularly, the material non-linearity is an important character of geo-engineering cases. Due to the randomness of materials’ spatial variation as well as boundary conditions’ fluctuation, these cases’ study incorporates stochastic theory. Stochastic finite element method is applicable for the randomness. The visco-plasto constitution is helpful for non-linear stochastic FEM application. The algorithm for non-linear stochastic FEM was established.

Effect of material heterogeneity on the deformation behaviour of multidirectional (1D/2D/3D) functionally graded composite panels

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kamal Kishore Joshi ◽  
Vishesh Ranjan Kar
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Deformation Behaviour ◽  
Functionally Graded ◽  
Composite Panels ◽  
Content Type ◽  
Material Heterogeneity ◽  
Functionally Graded Composite ◽  
Numerical Assessment ◽  
Support Conditions

Purpose The purpose of this study is the comprehensive numerical assessment of multidirectional (1D/2D/3D) functionally graded composite panel structures with different material gradation patterns and degrees of material heterogeneity. Here, deformation characteristics are obtained under different loading and support conditions. Design/methodology/approach The finite element solutions of multidirectional functionally graded composite panels subjected to uniform and sinusoidal transverse loads are presented under different support conditions. Here, different functionally graded composites, such as unidirectional (1D) and multidirectional (2D/3D), are considered by distributing constituent materials in one, two and three directions, respectively, using single and multivariable power-law functions. A constitutive model with fully spatial-dependent elastic stiffness is developed, whereas the kinematics of the present structure is defined using equivalent single-layer higher-order theory. The weak form, based on the principle of virtual work, is established and solved consequently using isoparametric finite element approximations via quadrilateral Lagrangian elements. Findings The appropriate mesh-refinement process is carried out to achieve the mesh convergence; whereas, the correctness of proposed heterogeneous model is confirmed through a verification test. The comprehensive numerical assessment of multidirectional functionally graded panels under various loading and support conditions depicts the importance of degree of material heterogeneity with different gradation patterns and volume-fraction exponents. Originality/value A comprehensive analysis on the deformation behaviour of 1D-functionally graded materials (FGMs) (X-FGM, Y-FGM and Z-FGM), 2D-FGMs (XY-FGM, YZ-FGM and XZ-FGM) and 3D-FGM composite panels FGM structures is presented. Multifaceted heterogeneous FGMs are modelled by varying constituent materials in one, two and three directions, using power-law functions. The constitutive model of multi-directional FGM is developed using fully spatial-dependent elastic matrix and higher-order kinematics. Isoparametric 2D finite element formulation is adopted using quadrilateral Lagrangian elements to model 1D/2D/3D-FGM structures and to obtain their deflection responses under different loading and support conditions.

Study on seismic behavior reduction of typical joints for monolithic precast concrete frame structures with ages

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Qidi Zhong ◽  
Jianguo Ding ◽  
Xiangxiang Zhang ◽  
Yin Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Constitutive Model ◽  
Service Time ◽  
Precast Concrete ◽  
Time Dependent ◽  
Frame Structures ◽  
Content Type ◽  
Concrete Frame ◽  
Nonlinear Springs

PurposeMonolithic precast concrete frame structures have been promoted and developed in recent years. Owing to material deterioration and a weaker structural integrity, monolithic precast concrete frame structures may suffer from insufficient seismic capacity as service time increases. A typical joint of monolithic precast concrete frame structure is studied in this paper. The purpose of this paper is to perform numerical modeling of the typical joint subjected to low cyclic load at different ages and analyze the hysteretic behavior reduction with ages under common atmosphere environment.Design/methodology/approachExisting un-carbonated concrete, carbonated concrete and corroded rebar are all considered as deterioration factors for the typical joint, whose constitutive models are introduced into the finite element model to study. Moreover, time-dependent constitutive model of existing un-carbonated concrete and mechanical model of bond between precast and cast-in-place concrete are established on the basis of existing experimental data. Then, finite element method is used to investigate the seismic property reduction of the typical joint, where nonlinear springs are set to simulate bonding between precast and cast-in-place concrete.FindingsAnalyzing the results, the reduction of reaction force from skeleton curves of the joint is significant in the first 30 years of service time, and slows down after 30 years. Besides, the ductility, secant stiffness and equivalent viscous damping coefficient of the typical joint remain almost unchanged in the first decade, but decrease obviously after 10 years.Originality/valueThe originality of the paper consists in the following. The time-dependent constitutive model of existing un-carbonated concrete is established and used in finite element method. Besides, bonding between precast and cast-in-place concrete is considered using nonlinear springs. There is a reference value for the seismic performance assessment of existing monolithic precast concrete frame structures.

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