Modelling size effect on rock aggregates strength using a DEM bonded-cell model

Huillca, Yoshiro; Silva, Matias; Ovalle, Carlos; Quezada, Juan Carlos; Carrasco, Sergio; Villavicencio, Gabriel

doi:10.1007/s11440-020-01054-z

Cited by 26 publications

(11 citation statements)

References 53 publications

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“…In particular, DEM strategies have proven to be quite advantageous since they provide a detailed description of the micromechanics of granular materials (e.g., particle connectivity, fabric anisotropy, contact force network, etc.) while being capable of dealing with collections of rigid [56,57] and deformable bodies [58][59][60] of varied sizes and shapes [61,62], under a large variety of boundary conditions.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Bespoke particle shapes in granular matter

2022

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Among granular matter, one type of particle has special properties. Upon being assembled in disordered configurations, these particles interlock, hook, almost braid, and – surprisingly, considering their relatively low packing fractions – show exceptional shear strength.Such is the case of non-convex particles. They have been used in the shapes of tetrapods, ‘L’, ‘Z’, stars, and many others, to protect coasts or build self-standing structures requiring no binders or external supports. Although these structures are often designed without a comprehensive mechanical characterization, they have already demonstrated great potential as highly resistant construction materials. Nevertheless, it is natural to attempt to find the most appropriate non-convex shapes for any given application. Can a particle shape be tuned to obtain a desired mechanical behavior? Although this question cannot be answered yet, current technological, simulation, and experimental developments strongly suggest that it can be resolved in the next decade. A clear understanding of the relationships between particle shapes, mechanical response, and packing properties will be key to providing insights into the behavior of these materials. Such work should stand on 1) robust and general shape descriptors that encode the complexity of non-convex shapes (i.e., the number of arms, the symmetries, and asymmetries of the bodies, the presence of holes, etc.), 2) the analysis of the response of assemblies under different loading conditions, and 3) the disposition and reliability of non-convex shapes to ensure durability. The manufacturing process and an efficient use of resources are additional elements that could further help to optimize particle shape. In the quest of designing bespoke non-convex particles, this paper consolidates the challenges that remain unresolved. It also outlines some routes to explore based on the latest developments in technology and research.

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Section: Numerical Simulationsmentioning

confidence: 99%

Bespoke particle shapes in granular matter

2022

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“…To provide mechanical strength to the assembly of cells, we used the bonded-cell method approach previously used in the simulation and analysis of crushable grains [9][10][11]. By adding a bonding law at the interfaces between cells (note that these interfaces are exclusively edge-edge contacts), the cells' interfaces can resist tensile and shearing stresses.…”

Section: Numerical Modelmentioning

confidence: 99%

Strength and energy consumption of inherently anisotropic rocks at failure

2021

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Using a discrete-element approach and a bonding interaction law, we model and test crushable inherently anisotropic structures reminiscent of the layering found in sedimentary and metamorphic rocks. By systematically modifying the level of inherent anisotropy, we characterize the evolution of the failure strength of circular rock samples discretized using a modified Voronoi tesselation under diametral point loading at different orientations relative to the sample’s layers. We characterize the failure strength, which can dramatically increase as the loading becomes orthogonal to the rock layers. We also describe the evolution of the macroscopic failure modes as a function of the loading orientation and the energy consumption at fissuring. Our simulation strategy let us conclude that the length of bonds between Voronoi cells controls the energy being consumed in fissuring the rock sample, although failure modes and strength are considerably changing. We end up this work showing that the microstructure is largely affected by the level of inherent anisotropy and loading orientation.

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“…This procedure generates an assembly of adjacent cells that we 'glue' using a cohesive bonding law. This approach, known as the bonded-cell method (BCM), has been used in numerous studies of the mechanical behavior of crushable granular materials, both in 2D (Nguyen et al, 2015) and 3D (Cantor et al, 2017;Orozco et al, 2019;Huillca et al, 2020).…”

Section: Construction Of Inherently Anisotropic Samplesmentioning

confidence: 99%

“…In addition, numerical studies have explored the effect of the number of cells on the failure strength of brittle materials, showing that an increased number of cells lowers the failure strength (Nguyen et al, 2015;Huillca et al, 2020). However, it was recently shown that the scalability of failure strength is not simply linked to the number of cells, but more importantly to the length of bonding interactions (Orozco et al, 2019;Cantor et al, 2021).…”

Section: Construction Of Inherently Anisotropic Samplesmentioning

confidence: 99%

Microstructural origins of crushing strength for inherently anisotropic brittle materials

Cantor¹,

Ovalle²,

Azéma³

2021

Preprint

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We study the crushing strength of brittle materials whose internal structure (e.g., mineral particles or graining) presents a layered arrangement reminiscent of sedimentary and metamorphic rocks. Taking a discrete-element approach, we probe the failure strength of circular-shaped samples intended to reproduce specific mineral configurations. To do so, assemblies of cells, products of a modified Voronoi tessellation, are joined in mechanically-stable layerings using a bonding law. The cells' shape distribution allows us to set a level of inherent anisotropy to the material. Using a diametral point loading, and systematically changing the loading orientation with respect to the cells' configuration, we characterize the failure strength of increasingly anisotropic structures. This approach ends up reproducing experimental observations and lets us quantify the statistical variability of strength, the consumption of the fragmentation energy, and the induced anisotropies linked to the cell's geometry and force transmission in the samples. Based on a fine description of geometrical and mechanical properties at the onset of failure, we develop a micromechanical breakdown of the crushing strength variability using an analytical decomposition of the stress tensor and the geometrical and force anisotropies. We can conclude that the origins of failure strength in anisotropic layered media rely on compensations of geometrical and mechanical anisotropies, as well as an increasing average radial force between minerals indistinctive of tensile or compressive components.

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Modelling size effect on rock aggregates strength using a DEM bonded-cell model

Cited by 26 publications

References 53 publications

Bespoke particle shapes in granular matter

Bespoke particle shapes in granular matter

Strength and energy consumption of inherently anisotropic rocks at failure

Microstructural origins of crushing strength for inherently anisotropic brittle materials

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