Measuring deformation processes in granular materials from intragranular to bulk scales

Granular materials (assemblies of contacting grains with inter-granular porosity) form a vast family of materials important in both natural and industrial contexts. Under mechanical loads such systems show complex behaviours relating to the inter- and intra-granular stresses, strains and force transmission as well as the individual grain kinematics and interactions leading to multi-scale, heterogeneous behaviour. To understand such systems requires detailed understanding of these different structures and processes at the pertinent scales. This paper provides a brief overview of some new opportunities for enhanced experimental description of structures and mechanisms relating to the deformation of granular materials exploiting the penetrating power of x-rays for both imaging, giving access to granular structures and their evolution, and diffraction-based measurements, giving access to intra-granular grain structure and changes as well as inter- and intra-granular force transmission.