Deformation Modes for Assemblies of Frictionless Polydisperse Spheres

Abstract:

The challenge of dealing with cohesive powders during storage, handling and transport are widely known in the process and pharmaceutical industries. Simulations with the discrete element method (DEM) provide further insight into the local microstructure of bulk materials. In this work, the DEM approach is presented to investigate the flow behavior of granular systems subjected to different modes of deformations. When uniaxial compression is applied of frictionless, polydisperse spheres above jamming (transition from fluid-like state to solid-like state), the evolution of coordination number (average number of contacts per particle) and pressure as functions of the volume fraction are, astonishingly, identical to results obtained for purely isotropic compression. Analytical predictions for the evolution of pressure and coordination number under isotropic strain can thus be separated from different deformation modes, as applied in this study. After two different modes of volume-conserving deviatoric shear, the results still compare quite well with results for purely isotropic compression. The difference between the two deviatoric modes and uniaxial deformation is examined with respect to the anisotropic stress response as a function of deviatoric strain.

• Periodical: Advanced Materials Research (Volume 508)
• Pages: 160-165
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.508.160
• Online since: April 2012
• Authors: Nishant Kumar, Olukayode I. Imole, Vanessa Magnanimo, Stefan Luding
• Keywords: DEM, Deviatoric Strain, Deviatoric Stress, Pure Shear Deformation, Uniaxial Deformation

References

[1] Luding, S., and Perdahcioglu, S., A local constitutive model with anisotropy for various homogeneous 2D Biaxial deformation modes, CIT 83(5), pp.672-688, (2011).

DOI: 10.1002/cite.201000180

[2] Göncü, F., Duran, O., and Luding, S., Constitutive relations for the isotropic deformation of frictionless packings of polydisperse spheres, C. R. Mecanique, 338, pp.570-586, (2010).

DOI: 10.1016/j.crme.2010.10.004

[3] Cundall P.A., Strack, O.D.L., A discrete numerical model for granular assemblies,. Geotechnique, 29, pp.47-65, (1979).

DOI: 10.1680/geot.1979.29.1.47

[4] Luding, S., Cohesive, frictional powders: contact models for tension, Granular Matter, 10, pp.235-246, (2008).

DOI: 10.1007/s10035-008-0099-x

[5] O'Hern, C. S., Silbert L. E., Liu A. J., and Nagel S. R., Jamming at zero temperature and zero applied stress: The epitome of disorder, Phys. Rev. E, 68, Part 1, (2003).

DOI: 10.1103/physreve.68.011306

[6] Magnanimo, V. and Luding, S., A local constitutive model with anisotropy for ratcheting under 2D biaxial isobaric deformation , Granular Matter, 13, No. 3, pp.225-232.

DOI: 10.1007/s10035-011-0266-3

[7] Imole, O. I., Kumar, N. and Luding, S., Deformation modes of packings of frictionless polydisperse spheres, in press, PSA2011 proceedings, Edinburgh, 5-7 Sept., (2011).

DOI: 10.4028/www.scientific.net/amr.508.160

[8] Imole, O. I., Kumar, N. and Luding, S., Different deformation modes of 3 dimensional packings of frictionless polydisperse spheres, in preparation.

DOI: 10.4028/www.scientific.net/amr.508.160

[9] Schwedes, J. and Schulze, D., 'Measurement of flow properties of bulk solids, Powder Technology, 61, p.59–68, (1990).

DOI: 10.1016/0032-5910(90)80066-8