Shake, Rattle, and Roll: Studying the kinematics of Sand Grains during Compression

However, the pervasive presence of granular materials masks how complicated it is to predict their mechanical response. Granular materials can behave as a solid foundation to a building, a flowing liquid down an incline, or as a gas when lifted into a storm. All these behaviors stem from how the contacts between grains evolve as load is applied. Recently published work from the F2 station at CHESS combined X-ray computed  micro-tomography, able to quantify the detailed shapes of individual sand grains, and high energy diffraction microscopy, able to quantify the loads being transferred through grains, to explore how the shapes of angular quartz sand grains influence the distribution of loads through the aggregate and subsequently how that load partitioning drives grain shifting and reorientation. In the paper it was found that grains preferentially spin around the loading axis when under compression in order to move into configurations which minimize the total height of the sample. In addition, as grains reorient, there is an accompanying rapid redistribution of load throughout the sample. This data will prove valuable for the creation of new constitutive models which enable us to predict how granular materials will respond to applied load.

Collaborators:

Ryan C. Hurley, Johns Hopkins University and Lawrence Livermore National Laboratory, rhurley6@jhu.edu

Eric B. Herbold, Lawrence Livermore National Laboratory

Darren C. Pagan, Cornell High Energy Synchrotron Source

Publication citation:

Hurley, R.C., Herbod, E.B. and Pagan, D.C. Characterization of the crystal structure, kinematics, stresses and rotations in angular granular quartz during compaction.  Journal of Applied Crystallography, 51(4), 1021-1034, doi.org/10.1107/S1600576718006957 August 2018.

Funding: