Title: Micromechanics of Granular Materials Across Time and Length Scales: Insights from Quasi-Static and Dynamic Testing with In-Situ X-ray Measurements

Abstract: Granular materials are the sands, soils, and powders that play central roles in geology, civil engineering, manufacturing, and defense. Although soils and powders have been used in applications for millennia, our ability to model and predict their behavior across time and length scales remains limited, particularly at high pressures relevant to many geophysical and defense applications. To improve predictions for such scenarios, we need new high-fidelity data and models capturing relationships between grain kinematics and stresses, particle breakage, and the effects of saturation. In this talk, I will first discuss our efforts to develop this data by constructing and using new high-pressure triaxial instruments for sands and sandstones amenable to in-situ laboratory and synchrotron X-ray measurements. I will discuss uses of this novel data for addressing open problems in granular mechanics and for calibrating constitutive models. I will then discuss experiments combining dynamic impact and penetration on sands (using gas guns and Kolsky bars) with in-situ X-ray imaging to quantify breakage, flow fields, and depth of penetration, and the implications of these experiments for calibrating models of dynamic material behavior. The audience will leave the talk with an appreciation of how in-situ X-ray measurements can improve our understanding of and ability to model granular materials across time and length scales.

Bio

Ryan Hurley is an Assistant Professor in the Department of Mechanical Engineering with a secondary appointment in the Department of Civil and Systems Engineering, and a Fellow of the Hopkins Extreme Materials Institute at the Johns Hopkins University (JHU). He received his B.S. in Civil Engineering from the University of Maryland, College Park (2011) and his M.S. and Ph.D. in Applied Mechanics from the California Institute of Technology (2012 and 2015). From 2015 - 2017, Ryan was a postdoctoral researcher in the Computational Geosciences Group at Lawrence Livermore National Laboratory in Livermore, California and an Assistant Research Professor at JHU. He joined JHU full-time as an Assistant Professor in January 2018. Ryan received the Department of Energy's Secretary's Appreciation Award in 2017, a 2020 NSF CAREER Award, the 2021 Army Educational Outreach Program's Mentor of the Year Award, and a 2022 Air Force Office of Scientific Research (AFOSR) YIP Award. Ryan's interests include studying the deformation and failure mechanisms of granular materials, rocks, concrete, and ceramics using advanced experimental techniques and modeling approaches.