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CMB Seminar – Ryan Hurley

May 16, 2019 | 12:00 pm - 1:00 pm

Title: Measuring Contact- and Particle-Scale Behavior in 3D Granular Materials with X-rays and Waves

 

Abstract:

Granular materials are ubiquitous in our everyday lives: coffee beans, rice grains, sands, soils, powders, and pills. Despite the ubiquity of granular materials, our understanding of their physical and mechanical behavior when packed, compressed, and sheared remains limited. One major challenge in understanding the behavior of granular materials has been in measuring their internal processes in 3D, including their inter-particle forces, particle fracture behavior, and frictional energy dissipation. These and other processes hold clues about the appropriate physical models that may describe granular materials. In this talk, I will discuss our recent experiments combining in-situ (i.e., during mechanical loading) X-ray computed tomography (XRCT) and 3D X-ray diffraction (3DXRD) measurements of 3D granular materials. XRCT provides high-resolution 3D images (with ~1 μm precision) of the evolving structure of real sands and particles as they are loaded. 3DXRD measurements provide the orientation (with 0.05° precision), the location (with a few μm precision), the strain tensor (with 10-4 precision), and the stress tensor (with ~6 MPa precision in quartz sand) of each particle in 3D. I will highlight through examples how the combination of these datasets is greater than the sum of their individual parts: the combination permits us to directly measure constitutive law parameters, to infer inter-particle forces, and to calculate inter-particle contact kinematics and frictional energy dissipation. I will discuss the connection between these measurements and some open problems in the study of granular materials. Finally, I will discuss some fascinating wave behaviors of granular materials and discuss our recent efforts to combine X-ray measurements with ultrasound transmission measurements to further probe their packing structure and vibrational modes.

Details

Date:
May 16, 2019
Time:
12:00 pm - 1:00 pm
Event Category:

Venue

Riddick 314