Simulation of the packing of granular mixtures of non-convex particles and voids characterization

Rémond, Sébastien; Gallias, Jean-Louis; Mizrahi, Amit

doi:10.1007/s10035-007-0082-y

Cited by 20 publications

(9 citation statements)

References 29 publications

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“…For example, certain faceted polyhedra pack into particularly dense aggregates, [13][14][15]17,23,24 while random packings of non-convex particles generically exhibit a much higher porosity. 26,[35][36][37][38] With spheres the average number of local contacts controls the mechanical response, and we can expect that denser packings of the same spheres will be stiffer. 20,29,[39][40][41] With non-convex shapes this no longer has to be the case, making it possible to envision highly porous packings that nevertheless excel in stiffness.…”

Section: Introductionmentioning

confidence: 99%

Particle shape effects on the stress response of granular packings

et al. 2014

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We present measurements of the stress response of packings formed from a wide range of particle shapes. Besides spheres these include convex shapes such as the Platonic solids, truncated tetrahedra, and triangular bipyramids, as well as more complex, non-convex geometries such as hexapods with various arm lengths, dolos, and tetrahedral frames. All particles were 3D-printed in hard resin. Well-defined initial packing states were established through preconditioning by cyclic loading under given confinement pressure. Starting from such initial states, stress-strain relationships for axial compression were obtained at four different confining pressures for each particle type. While confining pressure has the largest overall effect on the mechanical response, we find that particle shape controls the details of the stress-strain curves and can be used to tune packing stiffness and yielding. By correlating the experimentally measured values for the effective Young's modulus under compression, yield stress and energy loss during cyclic loading, we identify trends among the various shapes that allow for designing a packing's aggregate behavior.

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Section: Introductionmentioning

confidence: 99%

Particle shape effects on the stress response of granular packings

et al. 2014

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“…The spherosimplex representation is able to handle non-convex shapes with rounded corners/edges (as the skeleton is spanned by a disk or a sphere). The ultimate solution, that might be inefficient from a computational viewpoint as the collision detection step is certainly very time consuming, involves meshing the surface of the non-convex bodies, as attempted by Remond et al [34]. The method in [34] produced spectacular results on the packing of crushed hollow cylinders, but (serial) computations were limited to 10, 000 particles maximum.…”

Section: Introductionmentioning

confidence: 99%

Grains3D, a flexible DEM approach for particles of arbitrary convex shape—Part III: extension to non-convex particles modelled as glued convex particles

et al. 2018

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Large-scale numerical simulation using the Discrete Element Method (DEM) contributes to improve our understanding of granular flow dynamics involved in many industrial processes and geophysical flows. In industry, it leads to an enhanced design and an overall optimisation of the corresponding equipment and process. Most of DEM simulations in the literature have been performed using spherical particles. A limited number of studies dealt with non-spherical particles, even less with non-convex particles. Even convex bodies do not always represent the real shape of certain particles. In fact, more complex shaped particles are found in many industrial applications as, e.g., catalytic pellets in chemical reactors or crushed glass debris in recycling processes. In Grains3D-Part I [39], we addressed the problem of convex shape in granular simulations while in Grains3D-Part II [33], we suggested a simple through efficient parallel strategy to compute systems with up to a few hundreds of millions of particles. The aim of the present study is to extend even further the modeling capabilities of Grains3D towards non-convex shapes, as a tool to examine the flow dynamics of granular media made of non-convex particles. Our strategy is based on decomposing a non-convex shaped particle into a set of convex bodies, called elementary components. We call our method glued or clumped convex method, as an extension of the popular glued spheres method. Essentially, a non-convex particle is constructed as a cluster of convex particles, called elementary components. At the level of these elementary components of a glued convex particle, we employ the same contact detection strategy based on a Gilbert-Johnson-Keerthi algorithm and a linked-cell spatial sorting that accelerates the resolution of the contact, that we introduced in [39]. Our glued convex model is implemented as a new module of our code Grains3D and is therefore automatically fully parallel. We illustrate the new modeling capabilities of Grains3D in two test cases: (i) the filling of a container and (ii) the flow dynamics in a rotating drum.

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“…The mechanical response of these particles can be varied from soft to hard by tuning the thickness of the shell membrane [38,39]. There has been increased computational progress recently in modeling jammed granular packings of nonspherical particles [40][41][42][43][44][45], but experimental realizations are challenging. In our previous studies, we showed that the shape of our elastic shells can be tuned from a spherical to a nonspherical bowl shape of varying bowl depth by a buckling process [32].…”

Section: Introductionmentioning

confidence: 99%

Random three-dimensional jammed packings of elastic shells acting as force sensors

2016

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In a jammed solid of granular particles, the applied stress is in-homogeneously distributed within the packing. A full experimental characterization requires measurement of all the interparticle forces, but so far such measurements are limited to a few systems in two and even fewer in three dimensions. Particles with the topology of (elastic) shells are good local force sensors as relatively large deformations of the shells result from relatively small forces. We recently introduced such fluorescent shells as a model granular system in which force distributions can be determined in three dimensions using confocal microscopy and quantitative image analysis. An interesting aspect about these shells that differentiates them from other soft deformable particles is their buckling behavior at higher compression. This leads to deformations that do not conserve the inner volume of the particle. Here we use this system to accurately measure the contact forces in a three-dimensional packing of shells subjected to a static anisotropic compression and to shear. At small deformations forces are linear, however, for a buckled contact, the restoring force is related to the amount of deformation by a square root law, as follows from the theory of elasticity of shells. Near the unjamming-jamming transition (point J), we found the probability distribution of the interparticle forces P(f) to decay nearly exponentially at large forces, with little evidence of long-range force chains in the packings. As the packing density is increased, the tail of the distribution was found to crossover to a Gaussian, in line with other experimental and simulation studies. Under a small shear strain, up to 0.216, applied at an extremely low shear rate, we observed a shear-induced anisotropy in both the pair correlation function and contact force network; however, no appreciable change was seen in the number of contacts per particle.

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Simulation of the packing of granular mixtures of non-convex particles and voids characterization

Cited by 20 publications

References 29 publications

Particle shape effects on the stress response of granular packings

Particle shape effects on the stress response of granular packings

Grains3D, a flexible DEM approach for particles of arbitrary convex shape—Part III: extension to non-convex particles modelled as glued convex particles

Random three-dimensional jammed packings of elastic shells acting as force sensors

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