Compaction of elastic granular materials: inter-particles friction effects and plastic events

Vu, Thi-Lo; Nezamabadi, Saeid; Mora, Serge

doi:10.1039/c9sm01947b

Cited by 18 publications

(25 citation statements)

References 54 publications

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“…We note that both φ 0 and φ max slightly decline as the local friction increases. It is explained by the reduction of the particle rearrangements due to friction, as discussed in previous studies[73][74][75].In assemblies of rigid-deformable particles, φ max decreases as κ tends towards 0. On the same curves, we plot some of the compaction models found in the literature fitting our numerical results for μ s ∈ {0, 0.2} for all mixtures and μ s ∈ {0, 0.8} at κ = 1.…”

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confidence: 52%

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Compaction of mixtures of rigid and highly deformable particles: A micromechanical model

et al. 2020

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We analyze the isotropic compaction of mixtures composed of rigid and deformable incompressible particles by the nonsmooth contact dynamics approach. The deformable bodies are simulated using a hyperelastic neo-Hookean constitutive law by means of classical finite elements. We characterize the evolution of the packing fraction, the elastic modulus, and the connectivity as a function of the applied stresses when varying the interparticle coefficient of friction. We show first that the packing fraction increases and tends asymptotically to a maximum value φ max , which depends on both the mixture ratio and the interparticle friction. The bulk modulus is also shown to increase with the packing fraction and to diverge as it approaches φ max . From the micromechanical expression of the granular stress tensor, we develop a model to describe the compaction behavior as a function of the applied pressure, the Young modulus of the deformable particles, and the mixture ratio. A bulk equation is also derived from the compaction equation. This model lays on the characterization of a single deformable particle under compression together with a power-law relation between connectivity and packing fraction. This compaction model, set by well-defined physical quantities, results in outstanding predictions from the jamming point up to very high densities and allows us to give a direct prediction of φ max as a function of both the mixture ratio and the friction coefficient.

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confidence: 52%

Section: B Packing Construction Isotropic Compression and Dimensionless Parametersmentioning

confidence: 54%

Compaction of mixtures of rigid and highly deformable particles: A micromechanical model

et al. 2020

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“…As seen in previous studies, φ first increases with P/E from a well-known value φ 0 and then tends asymptotically to a maximum value φ max . Both φ 0 and φ max slightly decrease as the friction increases, which is explained by the rearrangements of the grains within the assembly, being more frequent in the frictionless case [23,24]. In addition, from the φ − P curve we computed the bulk modulus as K(φ) = dP dφ • dφ dε v , with ε v = − ln(φ 0 /φ), the macroscopic cumulative volumetric strain.…”

Section: Procedures and Resultsmentioning

confidence: 99%

A micro-mechanical compaction model for granular mix of soft and rigid particles

et al. 2021

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We use bi-dimensional non-smooth contact dynamics simulations to analyze the isotropic compaction of mixtures composed of rigid and deformable incompressible particles. Deformable particles are modeled using the finite-element method and following a hyper-elastic neo-Hookean constitutive law. The evolution of the packing fraction, bulk modulus and particle connectivity, beyond the jamming point, are characterized as a function of the applied stresses for different proportion of rigid/soft particles and two values of friction coefficient. Based on the granular stress tensor, a micro-mechanical expression for the evolution of the packing fraction and the bulk modulus are proposed. This expression is based on the evolution of the particle connectivity together with the bulk behaviour of a single representative deformable particle. A constitutive compaction equation is then introduced, set by well-defined physical quantities, given a direct prediction of the maximum packing fraction φmax as a function of the proportion of rigid/soft particles.

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“…In such a case, it is important to use low compression pressures when packaging the powder product to achieve particle rearrangement, resulting in a loose powder compact. Utilizing low pressures when plastically compressing respirable powders can also mitigate the deformation or fracturing of the particles (Chen et al, 2017;Raut et al, 2016;Sørensen et al, 2005;Vu et al, 2020), preserving the aerodynamic properties of the particles, while minimizing the volume of powder needed for each capsule. As a result, single-value density measurements, such as bulk and tapped density, are unsuitable for relatively cohesive respirable powders, so new methods are required for accurate and reproducible Compressed Bulk Density (CBD) measurements.…”

Section: Introductionmentioning

confidence: 99%

Modulated Uniaxial Compression Analysis of Respirable Pharmaceutical Powders

Barona

Shamsaddini

Aisenstat

et al. 2021

KONA

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We describe a new instrument and method for measuring compressed bulk density of respirable pharmaceutical powders under low compression pressure: the modulated compression tester. The instrument modulates compression and decompression steps, allowing scrutiny of the overall compression response of samples. Compared to established methods for the determination of density and related parameters for pharmaceutical powders, this instrument has the capability of measuring smaller samples. The relative humidity can also be controlled in the instrument (3 % to 95 % RH), allowing assessment of the effect of moisture on compression response. We have used the instrument to determine the compressed bulk density of Trehalose, Leucine, Trileucine, and Mannitol powders of varying crystalline and amorphous compositions and particle size and size distribution, demonstrating that the new modulated compression tester is suitable for low pressure (< 1200 kPa) density measurement of respirable powders (< 10 μm) and expensive active pharmaceutical ingredients available in limited quantities (typical sample mass requirement of < 100 mg). In addition, the modulation feature of the instrument allows the analysis of the transition from plastic to semi-elastic compression response. The outputs and features of this instrument are useful for formulation development, quality control measurements, discerning between different or similar powders due to differences in the compression response, and optimizing powder compression parameters for pharmaceutical applications.

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Compaction of elastic granular materials: inter-particles friction effects and plastic events

Abstract: The uni-axial compaction of granular materials made of elastic neo-Hookean particles is investigated in the quasi-static regime.

Cited by 18 publications

References 54 publications

Compaction of mixtures of rigid and highly deformable particles: A micromechanical model

Compaction of mixtures of rigid and highly deformable particles: A micromechanical model

A micro-mechanical compaction model for granular mix of soft and rigid particles

Modulated Uniaxial Compression Analysis of Respirable Pharmaceutical Powders

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