A novel three-dimensional contact model for granulates incorporating rolling and twisting resistances

Jiang, Mingjing; Shen, Zhifu; Wang, Jian Feng

doi:10.1016/j.compgeo.2014.12.011

Cited by 224 publications

(76 citation statements)

References 59 publications

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“…For example, interlocking of the particle cannot be captured with circular or spherical elements . In addition, the value of the shear strength among the granular particle assemblies are below those obtained experimentally …”

Section: Introductionmentioning

confidence: 83%

A novel discrete element method based on the distance potential for arbitrary 2D convex elements

Zhao

Liu

Jia

et al. 2018

Numerical Meth Engineering

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Summary A new 2‐dimensional discrete element method, which is able to simulate a system involving a large number of arbitrary convex elements, is proposed. In this approach, a novel distance potential function is defined using a normalized format of the penetrated distance between contact couples, while a holonomic and precise algorithm for contact interaction is established, accounting for the influence of the tangential contact force. Furthermore, the new contact detection algorithm is well suited for nonuniform blocks unlike the common no binary search method that requires uniform elements. The proposed method retains the merit of the combined finite‐discrete element method and avoids its deficiencies. Compared with the existing finite‐discrete element method, the distance potential function has a clear physical meaning, where the calculation of contact interaction avoids the influence of the element shape. Accordingly, the new method completely gets rid of the restraint of uniform element type and can be applied to arbitrary convex elements. The new method is validated with well‐known benchmark examples, and the results are in very good agreement with existing experimental measurement and analytical solutions. Finally, the proposed method is applied to simulate the Tangjiashan landslide.

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Section: Introductionmentioning

confidence: 83%

A novel discrete element method based on the distance potential for arbitrary 2D convex elements

Zhao

Liu

Jia

et al. 2018

Numerical Meth Engineering

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“…In case of an unbonded contact, a soft contact approach is used that allows for the formulation of appropriate constitutive force laws in normal direction (local compression) and tangential direction (sliding and sticking friction). Furthermore, a rotational resistance model, as descirbed in [4], captures the particleshape effect, such that the simplification of the particle geometry towards spheres is reasonable. Figure 1 shows evolved shear bands in simulations of a biaxial compression test on unbonded material and a uniaxial compression test on a cylindrical sample of a bonded material.…”

Section: Numerical Examplesmentioning

confidence: 99%

A homogenisation strategy for micromorphic continua based on particle mechanics

Bidier¹,

Ehlers²

2016

Proc Appl Math and Mech

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Materials with a granular microstructure frequently fail in narrow zones due to strain localisation. Examplarily, one may look at the shear-zone development in dry sand during bi-and triaxial loading, where grains in the shear-zone exhibit large displacements and rotations. Furthermore, localisation is also observed in materials, where the microstructure consists of grains and a binding material, such as for example metal-casting moulds. Here, sand grains are bound together via a polyurethanbased material and macroscopic material failure originates from the deformation and breakage of the binder material. Within a continuum-based modelling approach, these microstructural effects can be accounted for by the consideration of an additional microcontinuum at each material point of the macroscopic body. These extended continuum theories, such as the micromorphic continua and its micropolar and microstrain sub-formulations, assume a characteristic microcontinuum deformation on a lower scale and have been successfully applied in the field of granular media. Exemplarily, in the framework of a micropolar continua, it is possible to contact forces to stresses and couple stresses via an appropriate homogenisation technique. This method includes the introduction of a Representative Elementary Volume (REV) on the mesoscale situated between the particle and the continuum scale. In this contribution, a homogenisation strategy based on a particle-centre-based REV definition is presented that is generally valid for micromorphic and micropolar continua. Therefore, a grain-binder microstructure is investigated, where particle rotations contribute to the micropolar part, while binder deformations yield the additional macromorphic character. Numerical examples are given, where results from discrete-element simulations are locally averaged and show the individual activation of the microcontinuum characteristics in the localised zones. Homogenisation strategyA Representative Elementary Volume R is introduced on the mesoscale located between the macroscale of the overall body and the microscale of the particles. Thereby, an ensemble of particles forms the REV and its boundary is defined by the connection of the centres of mass of the boundary particles. Evaluating the balances of momentum and moment of momentum of a REV in an equilibrium state reveals its micropolar character, as surface couplesm arise due to the shifting of the surface stress vector t towards the particle's centre of mass at the REV-boundary, compare [1] for details. The stress state is hence described by non-symmetric stresses T and couple stressesM. This is the case for unbonded and bonded granular materials, as there is no formal difference whether contact stresses arise from direct collision of particles at contact points or from binder-material bridges that cover a larger surface area of the particles. The microstress that is associated with binder deformations in the REV is therefore identified through evaluation of the principle of virtual work [2], where the ...

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“…Indeed, grain shape may play a key role in forming the fabric structure of a granular assembly and through which the macroscopic responses of the material are affected (see, eg, the stress‐force‐fabric relationship). A popular indirect way to consider shape effect while using spherical particles for computational efficiency is the introduction of rolling resistance at interparticle contacts or the so‐called rolling resistance model . The rolling resistance model indeed helps to gain increased shear strength alone for granular materials but remains ineffective in reproducing other granular behaviors where grain shape has a clear imprint, such as the induced fabric structure, force transmission mechanisms, and deformation characteristics .…”

Section: Introductionmentioning

confidence: 99%

A poly‐superellipsoid‐based approach on particle morphology for DEM modeling of granular media

Zhao

2019

Num Anal Meth Geomechanics

117

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Summary Particle morphology plays a key role in affecting physical and mechanical behaviors of granular media. While various mathematical approaches and shape descriptors have been proposed to describe the morphological properties of granular particles, it remains a challenge to effectively incorporate them for efficient discrete modeling of granular materials. This study presents a new poly‐superellipsoid‐based approach for three‐dimensional discrete element method (DEM) modeling of non‐spherical convex particles. A uniform mathematical description of 3D poly‐superellipsoidal surface is employed to represent a realistic granular particle, which is shown to be versatile and effective in reproducing a wide range of shape features (including elongation, flatness, angularity, and asymmetry) for real particles in nature. A novel optimization approach based on hybrid Levenberg‐Marquardt (LM) and Gilbert‐Johnson‐Keerthi (GJK) algorithms is further developed for efficient and robust contact detection in DEM simulation of poly‐superellipsoidal assemblies. Simulations of granular packing and triaxial compression tests show that the proposed approach is generally robust and efficient for both dynamic and quasistatic modeling of granular media.

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A novel three-dimensional contact model for granulates incorporating rolling and twisting resistances

Cited by 224 publications

References 59 publications

A novel discrete element method based on the distance potential for arbitrary 2D convex elements

A novel discrete element method based on the distance potential for arbitrary 2D convex elements

A homogenisation strategy for micromorphic continua based on particle mechanics

A poly‐superellipsoid‐based approach on particle morphology for DEM modeling of granular media

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