Image-based calibration of rolling resistance in discrete element models of sand

Models that introduce rolling resistance at the contact are widely employed in simulations using the discrete element method (DEM) to indirectly represent particle shape effects. This approach offers substantial computational benefits at the price of increased calibration complexity. This work propo...

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Bibliographic Details
Published in:Computers and geotechnics 2021-03, Vol.131, p.103929, Article 103929
Main Authors: Rorato, R., Arroyo, M., Gens, A., Andò, E., Viggiani, G.
Format: Article
Language:English
Subjects:
Calibration
Compression
Computer applications
Correlation analysis
Discrete element method
Empirical analysis
Friction
Grain shape
Image acquisition
Image analysis
Image processing
Mapping
Mathematical models
Ooids
Parameters
Particle shape
Rolling resistance
Sand
Shape
Shape effects
Shear resistance
Triaxial compression tests
Triaxial test
X-rays micro tomography
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Summary:Models that introduce rolling resistance at the contact are widely employed in simulations using the discrete element method (DEM) to indirectly represent particle shape effects. This approach offers substantial computational benefits at the price of increased calibration complexity. This work proposes a method to simplify calibration of rolling resistance. The key element is an empirical relation between a contact parameter (rolling friction) and a 3D grain shape descriptor (true sphericity). Values of true sphericity can be obtained by image analysis of the grains, either directly by 3D acquisition or by correlation with simpler-to-obtain 2D shape measures. Evaluation of rolling friction is thus made independent from that of other model parameters. As an extra benefit, the variability of grain shape in natural sands can be directly mapped into the discrete model. A mapping between rolling friction and true sphericity is calibrated using specimen-scale and grain scale results from two triaxial compression tests on Hostun sand and Caicos ooids. The mapping is validated using different triaxial tests from the same sands and from other reference sands (Ottawa, Ticino). In the case of Ticino grain-shape acquisition is made in 2D, using an ordinary table scanner. The results obtained support this direct calibration procedure.
ISSN:0266-352X
1873-7633
DOI:10.1016/j.compgeo.2020.103929