On the relevance of the meso-scale in an upscaling approach for granular materials

Sinh Khoa Nguyen,Eric Vincens,Hélène Magoariec,Bernard Cambou,F Radjai,S Luding,J.Y Delenne,S Nezamabadi

doi:10.1051/epjconf/201714012002

Abstract

This paper deals with the interest of upscaling from a meso-scale understand and model the mechanical behavior of granular materials. The meso-domains associated to the meso-scale are defined as closed loops of particles in contact. Six sets of meso-domains with different local textures called “phases” have been defined. The analysis of the behavior of these phases through 2D DEMsimulations of a compression test followed by an extension test has allowed the discriminant evolution of the structure and then the role of the different phases at the meso-scale to be evidenced. Constitutive modeling of granular materials can advantageously be developed from the meso-scale where the principles of continuum mechanics apply.

Highlights

This paper deals with the interest of upscaling from a meso-scale understand and model the mechanical behavior of granular materials
An analysis of the behavior of these phases through 2D DEM simulations is provided. It tends to emphasize the key role of the meso-scale in an upscaling approach to model the mechanical behavior of granular materials
Upscaling from basic Delaunay cells cannot provide a correct upscaling because they do not hold a physical meaning as a local pore around which a mechanical transfer of forces is made possible

Summary

Introduction meso-domain m

A straightforward and reliable modeling of granular materials remains an open issue. An analysis of the behavior of these phases through 2D DEM simulations is provided. It tends to emphasize the key role of the meso-scale in an upscaling approach to model the mechanical behavior of granular materials. The numerical biaxial compression test is achieved using the commercial software PFC2D. The compaction process leads to an isotropic stress state of 100 kPa with a porosity of the sample equal to 0.167. From this isotropic state, the biaxial test consists of a loading stage followed by an unloading stage (Figure 5 – gray lines). Where Ed is the diagonal component of the incremental deviatoric strain tensor Ed

Definitions for the meso-scale

Evolution of the meso-structure

Conclusion

Upscaling process