Abstract
Soft, disordered, micro-structured materials are
ubiquitous in nature and industry, and are different from
ordinary fluids or solids, with unusual, interesting static and
flow properties. The transition from fluid to solid—at the socalled
jamming density—features a multitude of complex
mechanisms, but there is no unified theoretical framework
that explains them all. In this study, a simple yet quantitative
and predictive model is presented, which allows for
a changing jamming density, encompassing the memory of
the deformation history and explaining a multitude of phenomena
at and around jamming. The jamming density, now
introduced as a new state-variable, changes due to the deformation
history and relates the system’s macroscopic response
to its micro-structure. The packing efficiency can increase
logarithmically slow under gentle repeated (isotropic) compression,
leading to an increase of the jamming density. In
contrast, shear deformations cause anisotropy, changing the
packing efficiency exponentially fast with either dilatancy
or compactancy as result. The memory of the system near
jamming can be explained by a micro-statistical model that
involves a multiscale, fractal energy landscape and links
the microscopic particle picture to the macroscopic continuum
description, providing a unified explanation for the
qualitatively different flow-behavior for different deformation
modes. To complement our work, a recipe to extract
the history-dependent jamming density from experimentally
accessible data is proposed, and alternative state-variables are compared. The proposed simple macroscopic constitutive
model is calibrated from particles simulation data, with
the variable jamming density—resembling the memory of
microstructure—as essential novel ingredient. This approach
can help understanding predicting and mitigating failure of
structures or geophysical hazards, and will bring forward
industrial process design and optimization, and help solving
scientific challenges in fundamental research.
Original language | English |
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Article number | 58 |
Number of pages | 21 |
Journal | Granular matter |
Volume | 18 |
DOIs | |
Publication status | Published - 2 Jun 2016 |
Keywords
- IR-101359
- METIS-318002