DEM simulation of anisotropic granular materials: elastic and inelastic behavior

Recchia, Giuseppina; Magnanimo, Vanessa; Cheng, Hongyang; Ragione, Luigi La

doi:10.1007/s10035-020-01052-8

Cited by 11 publications

(9 citation statements)

References 41 publications

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“…This is the regime in which q T is constant while q N keeps growing. Here, Recchia et al [10] find, at contact level, that particles slide and roll confirming no increment in the tangential forces and supporting the idea that the increment in the contact forces occurs only along the normal component. It is expected that in a later stage shear bands will occur with major fabric changes and dilatancy, with particles failing into (larger) gaps steadily.…”

Section: Results: Acoustic Tensorsupporting

confidence: 79%

“…As an example, in Figure 3 we show the evolution of the stiffness component A 1111 with the strain amplitude. As reported in [10,16,17], the first plateau refers to the elastic response in which the perturbation is so small to prevent sliding and rolling among particles. The second plateau is associated with an inelastic, yet linear, incremental response, that preserves the micro-and macromechanisms happening during axial loading.…”

Section: Stiffness Tensormentioning

confidence: 85%

“…This phenomena may precede localization [9] but both second-order work and determinant of the acoustic tensor are zero when localization occurs. Here we focus on the acoustic tensor and evaluate the effective moduli via numerical simulations, following Recchia et al [10]. We show that localization is plausible in a regime of deformation where the incremental material behavior is governed by normal forces.…”

Section: Introductionmentioning

confidence: 87%

“…During the simulation, the average stress is calculated following the Cauchy relation for molecular systems (e.g. [10]).…”

Section: Dem Simulationmentioning

confidence: 99%

“…Along the compression path, we consider different stress states and evaluate the non zero components of the stiffness tensor. As shown in Recchia et al [10], for each point, we apply strain perturbations ∆ pq in the forward direction, i.e. consistent with loading along the triaxial stress path, so that if particles were sliding or rolling during the axial loading, they continue to do so during the probe.…”

Section: Stiffness Tensormentioning

confidence: 99%

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Failure in granular materials based on acoustic tensor: a numerical analysis

et al. 2021

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We investigate localization in granular material with the support of numerical simulations based upon DEM (Distinct Element Method). Localization is associated with a discontinuity in a component of the incremental strain over a plane surface through the condition of the determinant of the acoustic tensor to be zero. DEM simulations are carried out on an aggregate of elastic frictional spheres, initially isotropically compressed and then sheared at constant pressure p0. The components of the stiffness tensor are evaluated numerically in stressed states along the triaxial test and employed to evaluate the acoustic tensor in order to predict localization. This occurs in the pre-peak region, where the aggregate hardens under the circumstance to be incrementally frictionless: it is a regime in which the tangential force does not change as the deformation proceedes and, consequently, the deviatoric stress varies only with the normal component of the contact force.

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Section: Results: Acoustic Tensorsupporting

confidence: 79%

Section: Stiffness Tensormentioning

confidence: 85%

Section: Introductionmentioning

confidence: 87%

“…During the simulation, the average stress is calculated following the Cauchy relation for molecular systems (e.g. [10]).…”

Section: Dem Simulationmentioning

confidence: 99%

Section: Stiffness Tensormentioning

confidence: 99%

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Failure in granular materials based on acoustic tensor: a numerical analysis

et al. 2021

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Micro‐mechanism of stress‐dilatancy anisotropy in granular materials: Affine and nonaffine deformation

Liu,

Wang

2024

Num Anal Meth Geomechanics

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The stress‐induced dilatancy anisotropy is an important kinematic response in granular materials and is very complex due to the stochastic motion of particles. In this study, the local stress‐dilatancy relationship is investigated referring to the local contact force and relative displacement in a certain contact direction. The micromechanism of this anisotropy is investigated from the view of affine and nonaffine approaches based on DEM simulation. Numerical results indicate that the local nonaffine dilatancy/contraction tendency is opposite with that of local affine deformation in macroscopic compression and extension direction, which mainly stems from the counteraction effect between the normal components of affine and nonaffine displacements. The local stress‐dilatancy of affine and nonaffine components is linear and orientation‐dependent, which results in the nonlinear character of macroscopic stress‐dilatancy. By establishing an analytical relation of stress‐dilatancy, the local affine/nonaffine dilatancy is decomposed into the component of stress‐induced dilatancy synchronized with the local stress anisotropy; and the component of stress‐induced dilatancy asynchronized with the local stress anisotropy. The former is related to the unchanged isotropic microstructure, and the latter attributes to the anisotropic microstructure. Besides, the contribution of nonsliding contacts to nonaffine dilatancy is larger than that of sliding contacts even for the case of relatively higher sliding ratio, which indicates that the heterogeneous deformation attributes not only to the friction dissipation, but to the blocked energy at micro contacts in granular materials.

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Fluctuations and failure in granular materials: theory and numerical simulations

La Ragione,

Recchia,

Darve

et al. 2024

Granular Matter

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We consider a dense aggregate of elastic, frictional particles isotropically compressed and next uniaxial strained at constant pressure. We show how failure can be predicted if fluctuations in the kinematics of contacting particles are introduced. We focus on the second order work and the possibility that at some stressed states it becomes negative under proper perturbations. Our analysis involves both a theoretical model and numerical simulations based upon the distinct element method (DEM). The theoretical model deals with contacting particles with incremental relative displacements that deviate from the average deformation in order to ensure their equilibrium. Because of this, the macroscopic stiffness tensor of the aggregate, that relates increments in stress with increments in strain, does not have the major symmetry. Consequently, in the hardening regime, we predict stressed states in which the second order work vanishes. The model seems transparent, and it makes clear and illustrative the role played by the fluctuations introduced in the kinematics of contacting particles in relation to the vanishing of second order work in an aggregate of compressed particles. The comparison with numerical simulations data supports the model. Graphical Abstract Statistical representation of the aggregate: conditional average.

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DEM simulation of anisotropic granular materials: elastic and inelastic behavior

Cited by 11 publications

References 41 publications

Failure in granular materials based on acoustic tensor: a numerical analysis

Failure in granular materials based on acoustic tensor: a numerical analysis

Micro‐mechanism of stress‐dilatancy anisotropy in granular materials: Affine and nonaffine deformation

Fluctuations and failure in granular materials: theory and numerical simulations

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