The discrete element method (DEM) proposed by Cundall and Strack  is a widely used numerical approach to study the fundamentals of particulate matter at the particle scale. In our present study, the flow behavior of dense configurations of soft particles was studied by means of a new formulation of the multi-contact force closure for the DEM. The first step was to verify the response of the new force closure, and calibrate its parameters based on a comparison of the results for simple uniaxial compression with results from a reference simulation. This reference simulation used a highly accurate nonlocal formulation of contact mechanics in the quasi-static limit , which accounts for the interplay of deformations due to multiple contact forces acting on a single particle. The newly developed and calibrated model results show significant improvement over those derived via the existing multi-contact model. Also, the dependence of the stress in the sheared granular matter on the Poisson's ratio was unveiled when using the newly derived advanced multi-contact force closure. Therefore, an extensive campaign of simple shear flow simulations was performed (at a fixed volume of the simulation box) to probe the effect of particle volume fraction and the speed of shearing. These simulations show that the stress at particle volume fractions larger than a critical value depends not only on the friction coefficient and particle stiffness, but also on the Poisson's ratio of the material. Finally, we report a response surface for the pressure in a sheared particle bed as a function of all key influence parameters. This response surface is beneficial for calibrating DEM model parameters in extremely dense flow configurations.
|Number of pages||13|
|Publication status||Published - Mar 2022|
Bibliographical noteFunding Information:
TU Graz researchers acknowledge discussions with Arno Mayrhofer at DCS Computing on implementation details of the original multi-contact force closure and fruitful discussions with Mohammadsadegh Salehi for assessing the shortcomings of the standard multi-contact closure. Financial support by the European Union's Horizon 2020 Marie Skłodowska-Curie grant ‘CALIPER’ (No. 812638), and by NAWI Graz (via access to its HPC computing resource dcluster.tugraz.at ) is acknowledged by TU Graz researchers. Poorsolhjouy gratefully acknowledges the financial support provided by Sectorplan Techniek, Netherlands.
- Deformable particles
- Discrete element method
- Response surfaces
- Simple shear flow