Investigating the micromechanical evolutions within inherently anisotropic granular materials using discrete element method

Hosseininia, Ehsan Seyedi

doi:10.1007/s10035-012-0340-5

Cited by 76 publications

(29 citation statements)

References 54 publications

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“…As given in Eq. (7), the normal contact force is related to the volume of the contact overlap, which is extended from the 2D case [10,11]. This contact law was verified by other investigators [25][26][27][28].…”

Section: Contact Force Lawmentioning

confidence: 60%

“…The difference can be explained as follows: spherical particles can rotate freely during shearing; and it is easy for them to overturn around the neighbor, thereby more easily moving in the direction of horizon than vertical. The macroscopic mechanical behavior of a granular assembly is dependent on the evolution of inner fabric during shearing [11,13,37]. In the following sections, the evolutions of coordination number, contact force chain and anisotropy will be presented and discussed.…”

Section: Macro Shear Behaviormentioning

confidence: 99%

“…Anisotropy is regarded as one of the most important characteristics of granular assemblies, and it has been taken into consideration for better understanding of the corresponding mechanical behavior [11,37,42,43]. There are mainly two types of anisotropy in granular assemblies, i.e., inherent anisotropy and induced anisotropy.…”

Section: Anisotropymentioning

confidence: 99%

“…Therefore, non-circular and nonspherical shapes have to be considered. Some investigations were conducted using ellipses [9], polygons [10,11], spherepolygons [12] and clumped discs [13], where the results are reasonable but limited to 2D cases. To have a better understanding of effects of particle shape, ellipsoids [14], clusters of spheres [15], spherocylinders [16] and superquadric shapes [17], and so forth, were used.…”

Section: Introductionmentioning

confidence: 99%

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Discrete element simulations of direct shear tests with particle angularity effect

2015

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This paper investigated the effect of the particle angularity in light of its importance in angular particle assemblies, using the discrete element method (DEM). A discrete element model with a general contact force law for arbitrarily shaped particles was developed, in which angular particles were modeled using convex polyhedra. Quasi-spherical polyhedral shapes with different vertexes were adopted to reflect the change of angularity. Four categories of assemblies with different angularities were generated. A series of direct shear tests performed on these assemblies were simulated at different vertical stresses. All numerical implementations were achieved using a modified version of the open source DEM code YADE. It was found that the macroscopic shear strength and dilatancy characteristics are in agreement with experimental and numerical results in the literature, indicating that the present numerical model is reasonable. Besides, the evolutions of coordination number, normal contact force distribution, and anisotropies of particle orientation and contact normal were investigated. The results show that the angularity plays a vital role in strengthening the interlocking of angular particles.

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Section: Contact Force Lawmentioning

confidence: 60%

Section: Macro Shear Behaviormentioning

confidence: 99%

Section: Anisotropymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Discrete element simulations of direct shear tests with particle angularity effect

2015

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“…Ng and Dobry [35] explored the use of discrete element simulations to model granular soil response and the results indicated that the stress-strain curve observed in laboratory tests on sands was well reproduced by the numerical simulations. Hosseininia [36] pointed out that the evolution of normal contact force chains revealed the development of new contacts. Jiang et al [37] investigated the propagation of microcracks of sands by two-dimensional distinct element method.…”

Section: Mathematical Problems In Engineeringmentioning

confidence: 99%

DEM Investigation of Particle-Scale Mechanical Properties of Frozen Soil Based on the Nonlinear Microcontact Model Incorporating Rolling Resistance

Xue

Geng

et al. 2018

Mathematical Problems in Engineering

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Although frozen soil is in nature the discrete material, it is generally treated as the continuum material. The mechanical properties of frozen soil are so complex to describe adequately by conventional continuum mechanics method. In this study, the nonlinear microcontact model incorporating rolling resistance is proposed to investigate the particle-scale mechanical properties of frozen soil. The failure mechanism of frozen soil is explicated based on the evolution of contact force chains and propagation of microcracks. In addition, the effects of contact stiffness ratio and friction coefficient on stress-strain curve and energy evolution are evaluated. The results show that the nonlinear microcontact model incorporating rolling resistance can better describe the experimental data. At a higher axial strain, the contact force chains near shear band which can give rise to the soil arch effect rotate away from the shear band inclination but not so much as to become perpendicular to it. The propagation of microcracks can be divided into two phases. The stress-strain curve is strongly influenced by contact stiffness ratio. In addition, friction coefficient does not significantly affect the initial tangential modulus. Compared with frictional coefficient, the effect of contact stiffness ratio on stress-strain curve and energy evolution is greater.

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FEM×DEM multi‐scale model for cemented granular materials: Inter‐ and intra‐granular cracking induced strain localisation

Nguyen

Desrues

et al. 2022

Num Anal Meth Geomechanics

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In this paper, we present a multi‐scale model that combines the finite element method (FEM) and the discrete element method (DEM) to study the behaviour of cemented granular materials (CGM) at both the sample (macroscopic) and particle (microscopic) scales, taking into account inter‐ and intra‐granular cracking. At the microscopic scale, the material is made up of Volume Elements (VE) composed of particles. Their mechanical behaviour is modelled by the DEM. In the VEs, we find circular grains (single particles) and meso‐grains; the meso‐grains being made up of clusters of particles linked by strong cohesive bonds. All particles interact via normal/tangential contact and rolling resistance laws with cohesive bonds. At the macroscopic scale, the sample is modelled using the FEM. A VE is assigned to each Gauss point of the mesh; the mechanical response of the VE is used to numerically derive the constitutive response of the material to the strain increment exerted at each point. In the models reported in this paper, localised failures in shear band mode are observed at the macroscopic scale. By performing a microscopic analysis, the results show that the occurrence and development of shear bands give rise locally to a strong evolution of microscopic characteristics such as void ratio, number of contacts (total and debonding contacts), and remarkably by inter‐ and intra‐granular cracking in the case of meso‐grains. Furthermore, the stress and strain tensors non‐coaxiality is clearly demonstrated inside the shear band, but almost negligible outside.

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Investigating the micromechanical evolutions within inherently anisotropic granular materials using discrete element method

Cited by 76 publications

References 54 publications

Discrete element simulations of direct shear tests with particle angularity effect

Discrete element simulations of direct shear tests with particle angularity effect

DEM Investigation of Particle-Scale Mechanical Properties of Frozen Soil Based on the Nonlinear Microcontact Model Incorporating Rolling Resistance

FEM×DEM multi‐scale model for cemented granular materials: Inter‐ and intra‐granular cracking induced strain localisation

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