A spherical discrete element model: calibration procedure and incremental response

Plassiard, Jean‐Patrick; Belheine, Noura; Donzé, Frédéric‐Victor

doi:10.1007/s10035-009-0130-x

Cited by 128 publications

(93 citation statements)

References 17 publications

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“…Once these three parameters are calibrated with high accuracy (posterior probability), the true values for the rolling parameters β m and η m can be identified by tuning the evolution of post-peak stress ratio over axial or deviatoric strain. It is worth noting that this technique is often adopted in the literature, because rolling stiffness and rolling friction can significantly affect the bulk shear strength, but have a negligible influence on the initial elastic behavior and dilatancy of a dense granular material [38].…”

Section: Correlations Between Micro-and Macro-mechanical Parametersmentioning

confidence: 99%

“…For DEM simulations of rocks [7,27,50] in which intergranular forces depend linearly on relative displacements between adjoining grains, a linear correlation between the bulk Young's modulus and the normal contact stiffness was identified, whereas a nonlinear correlation was found for sandy soils [38]. Given a constant value for the normal contact stiffness, both Young's modulus and Poisson's ratio were found to be linearly related to the tangential contact stiffness [4,38], despite the fact that normal and tangential stiffnesses can jointly affect the deformability of a granular material. The micromechanical parameters that characterize deformability (e.g., contact stiffnesses) and yield (e.g., intergranular friction angle), however, are generally believed to be uncoupled, and thus can be calibrated separately.…”

Section: Introductionmentioning

confidence: 99%

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Probabilistic calibration of discrete element simulations using the sequential quasi-Monte Carlo filter

et al. 2018

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The calibration of discrete element method (DEM) simulations is typically accomplished in a trial-and-error manner. It generally lacks objectivity and is filled with uncertainties. To deal with these issues, the sequential quasi-Monte Carlo (SQMC) filter is employed as a novel approach to calibrating the DEM models of granular materials. Within the sequential Bayesian framework, the posterior probability density functions (PDFs) of micromechanical parameters, conditioned to the experimentally obtained stress-strain behavior of granular soils, are approximated by independent model trajectories. In this work, two different contact laws are employed in DEM simulations and a granular soil specimen is modeled as polydisperse packing using various numbers of spherical grains. Knowing the evolution of physical states of the material, the proposed probabilistic calibration method can recursively update the posterior PDFs in a five-dimensional parameter space based on the Bayes' rule. Both the identified parameters and posterior PDFs are analyzed to understand the effect of grain configuration and loading conditions. Numerical predictions using parameter sets with the highest posterior probabilities agree well with the experimental results. The advantage of the SQMC filter lies in the estimation of posterior PDFs, from which the robustness of the selected contact laws, the uncertainties of the micromechanical parameters and their interactions are all analyzed. The micro-macro correlations, which are byproducts of the probabilistic calibration, are extracted to provide insights into the multiscale mechanics of dense granular materials.

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Section: Correlations Between Micro-and Macro-mechanical Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probabilistic calibration of discrete element simulations using the sequential quasi-Monte Carlo filter

et al. 2018

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“…For example [3,39] once calibrated, the predictive capabilities of the numerical model will be checked by simulating other triaxial tests. For the calibration step, the selected local parameters are: K n , K s , K r (or β r ), µ and η r .…”

Section: Calibration Of the Local Parametersmentioning

confidence: 99%

YADE‐OPEN DEM: an open‐source software using a discrete element method to simulate granular material

Kozicki

Donzé

2009

Engineering Computations

187

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Purpose -YADE-OPEN DEM is an open source software based on the Discrete Element Method which uses object oriented programming techniques. The paper describes the software architecture. Design/methodology/approach -The DEM chosen uses position, orientation, velocity and angular velocity as independent variables of simulated particles which are subject to explicit leapfrog time-integration scheme (Lagrangian method). The three-dimensional dynamics equations based on the classical Newtonian approach for the second law of motion are used. The track of forces and moments acting on each particle is kept at every time-step. Contact forces depend on the particle geometry overlap and material properties. The normal, tangential and moment components of interaction force are included. Findings -An effort has been undertaken to extract the underlying object oriented abstractions in the Discrete Element Method. These abstractions were implemented in C++, conform to object oriented design principles and use design patterns. Based on that, a software framework was developed in which the abstractions provide the interface where the modelling methods can be plugged-in. Originality/value -The resulting YADE-OPEN DEM framework is designed in a generic way which provides great flexibility when adding new scientific simulation code. Some of the advantages are that numerous simulation methods can be coupled within the same framework while plug-ins can import data from other software. In addition, this promotes code improvement through open source development and allows feedback from the community. However implementing such models requires that one adheres to the framework design and the YADE framework is a new emerging software. To download the software see http://yade.wikia.com webpage.

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“…As for DEM numerical simulations, previous studies highlight the great influence of microscopic friction on the volumetric response [34,62]. Taking into account the facts previously commented, in the present investigation the replication of the experimental soil condition during DEM simulations involves the implementation of a new inter-particle friction coefficient in the true triaxial code.…”

Section: Relative Densitymentioning

confidence: 81%

“…Although there is no real soil with constant microscopic friction values for every particle, this is a possibility of the numerical simulation and renders a convenient method to obtain the dense state required here. It is worth to mention that typical friction values for sands range between 0.3 and 0.6; the use of such values would only produce loose samples [62].…”

Section: Relative Densitymentioning

confidence: 99%

Micromechanical study of granular assemblies by true triaxial test simulations

Hurtado¹,

Jonathan²

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Geomaterials, such as soils and rocks, are discontinuous and multiphase in nature since they are a mix of particulate elements and different constituents. The discrete nature of geomaterials yields a complex media to deal with regarding predictive capabilities that can only be achieved through expensive computational simulations. The computational modelling of geotechnical problems may consider continuum mechanics or discrete element frameworks to simulate the behaviour of all the features involved. Undoubtedly, continuum-based simulation techniques are predominant in geotechnical engineering practice and have significantly influenced our comprehension of soil response. However, continuum simulations do not consider special features of granular matters at the grain scale that finally determine the characteristic behaviour of particulate materials. On the other hand, the Discrete Element Method (DEM) is in fact based on the inter-particle physical processes at the micro-scale and, in the last decades, has been widely used to simulate a large range of geomaterials, allowing quantitative and qualitative analyses.However, it lacks the scalability and efficiency of models based on continua.This investigation is focused on the modelling of the macroscopic mechanical response of granular assemblies, as a natural consequence of their micromechanical properties, but employing the micro-/mesoscopic method described above. Simulations of true triaxial tests (TTT), an important test in geotechnical engineering, using 3D virtual soil samples are executed with an advanced DEM code that can model assemblies of grains that are made of spherical or non-spherical particles. A DEM-based calibration methodology is thus proposed giving insights on the reliability of the discrete method to replicate soils' mechanical behaviour.ii

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A spherical discrete element model: calibration procedure and incremental response

Cited by 128 publications

References 17 publications

Probabilistic calibration of discrete element simulations using the sequential quasi-Monte Carlo filter

Probabilistic calibration of discrete element simulations using the sequential quasi-Monte Carlo filter

YADE‐OPEN DEM: an open‐source software using a discrete element method to simulate granular material

Micromechanical study of granular assemblies by true triaxial test simulations

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