The Physics of Granular Mechanics

On the scaling of fragmentation and energy dissipation in collisions of dust aggregates

Granular Matter ◽

10.1007/s10035-021-01101-w ◽

2021 ◽

Vol 23 (2) ◽

Author(s):

Philipp Umstätter ◽

Herbert M. Urbassek

Keyword(s):

Energy Dissipation ◽

Collision Energy ◽

Velocity Range ◽

Collision Velocity ◽

Granular Mechanics ◽

Extra Factor ◽

Cluster Fragmentation ◽

Silica Clusters ◽

Large Clusters ◽

Small Clusters

Abstract Fragmentation of granular clusters may be studied by experiments and by granular mechanics simulation. When comparing results, it is often assumed that results can be compared when scaled to the same value of $$E/E_{\mathrm{sep}}$$ E / E sep , where E denotes the collision energy and $$E_{\mathrm{sep}}$$ E sep is the energy needed to break every contact in the granular clusters. The ratio $$E/E_{\mathrm{sep}}\propto v^2$$ E / E sep ∝ v 2 depends on the collision velocity v but not on the number of grains per cluster, N. We test this hypothesis using granular-mechanics simulations on silica clusters containing a few thousand grains in the velocity range where fragmentation starts. We find that a good parameter to compare different systems is given by $$E/(N^{\alpha }E_{\mathrm{sep}})$$ E / ( N α E sep ) , where $$\alpha \sim 2/3$$ α ∼ 2 / 3 . The occurrence of the extra factor $$N^{\alpha }$$ N α is caused by energy dissipation during the collision such that large clusters request a higher impact energy for reaching the same level of fragmentation than small clusters. Energy is dissipated during the collision mainly by normal and tangential (sliding) forces between grains. For large values of the viscoelastic friction parameter, we find smaller cluster fragmentation, since fragment velocities are smaller and allow for fragment recombination. Graphic abstract

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Introduction to Computational Granular Mechanics

Behaviour of Granular Materials ◽

10.1007/978-3-7091-2526-7_2 ◽

1998 ◽

pp. 99-169 ◽

Cited By ~ 15

Author(s):

J. P. Bardet

Keyword(s):

Granular Mechanics

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Asphalt-Mixture Force Chains Length Distribution and Skeleton Composition Investigation Based on Computational Granular Mechanics

Journal of Materials in Civil Engineering ◽

10.1061/(asce)mt.1943-5533.0003633 ◽

2021 ◽

Vol 33 (4) ◽

pp. 04021033

Author(s):

Guoqiang Liu ◽

Dongdong Han ◽

Cunzhen Zhu ◽

Fengfeng Wang ◽

Yongli Zhao

Keyword(s):

Asphalt Mixture ◽

Length Distribution ◽

Force Chains ◽

Granular Mechanics

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New Micromechanics Formulations for the Assessment of Elastic Moduli of Granular Assemblies

Engineering Technology Conference on Energy, Parts A and B ◽

10.1115/etce2002/ot-29019 ◽

2002 ◽

Author(s):

Linbing Wang ◽

Emir Macari ◽

Eyassu Woldesenbet

Keyword(s):

Elastic Moduli ◽

New Method ◽

Granular Mechanics ◽

Volume Fractions ◽

Granular Assemblies ◽

The Matrix ◽

Particle Shapes

The elastic moduli of granular assemblies are sensitive to the confining conditions as well as the volume fractions of each of its constituents (i.e. solid, fluid, gas). Theoretical estimations using granular mechanics are based on assumed distributions of contact normals and branch vectors using idealized particle shapes and therefore cannot quantitatively predict the moduli. This paper presents a new method to use the moduli of the granular skeleton and those of the matrix to estimate the moduli of the composite and makes it possible to back-calculate the moduli of the skeleton from the moduli of the composite and the matrix.

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