CESS Seminar : Mechanics of Rapidly Compacted Granular Materials Across Length Scales: Insights from X-ray Imaging and Modeling
Abstract
Granular materials are subjected to high pressures and strain rates during geophysical processes and in engineering and defense applications. The mechanics of granular materials under these conditions is complex and involves a combination of microscopic processes such as grain breakage and meso- and macroscopic processes such as deformation banding. Constitutive models used to predict responses to impact and penetration are increasingly making use of our knowledge of how microscopic and mesoscopic processes progress. Here, we discuss efforts to understand and predict rapid compaction and penetration of dry and fully saturated granular materials at length scales ranging from individual grains and pores to bulk scales. We primarily focus on experimental developments and their connections to continuum constitutive models. We first discuss small-scale planar compaction experiments which leverage x-ray imaging and time-resolved x-ray phase contrast imaging. These experiments are combined with digital twin modeling to quantify pore collapse, stress concentrations, and dynamic force chains in 3D at the grain scale. We then discuss penetration experiments at the bulk scale which employ flash x-ray imaging and a novel method of 3D flow field reconstruction. Bulk scale experiments are compared with a continuum constitutive model uniquely informed by other tests which quantify grain-scale processes such as a grain breakage. The audience will leave the talk with an appreciation of how in-situ imaging and analysis can be used to inform our understanding of and modeling capabilities for dynamic processes in granular materials.
Short bio
Ryan Hurley is an Associate Professor in the Department of Mechanical Engineering with a secondary appointment in the Department of Civil and Systems Engineering, and a Faculty Fellow of the Hopkins Extreme Materials Institute at the Johns Hopkins University (JHU). Before joining JHU in 2018, Ryan received his Ph.D. in Applied Mechanics from Caltech and worked as a postdoc in computational geomechanics at Lawrence Livermore National Laboratory. Ryan has received a 2017 Department of Energy’s Secretary’s Appreciation Award, a 2020 NSF CAREER Award, a 2021 Army Education Outreach Program’s Mentor of the Year Award, and a 2022 Air Force Office of Scientific Research (AFOSR) Young Investigator Program Award. Ryan’s research interests include studying the deformation and failure mechanisms of granular materials, rocks, and concrete using advanced experimental techniques, such as in-situ x-ray imaging and diffraction, constitutive modeling, and micromechanics.
Sandwiches are offered at the end of the seminar.
Granular materials are subjected to high pressures and strain rates during geophysical processes and in engineering and defense applications. The mechanics of granular materials under these conditions is complex and involves a combination of microscopic processes such as grain breakage and meso- and macroscopic processes such as deformation banding. Constitutive models used to predict responses to impact and penetration are increasingly making use of our knowledge of how microscopic and mesoscopic processes progress. Here, we discuss efforts to understand and predict rapid compaction and penetration of dry and fully saturated granular materials at length scales ranging from individual grains and pores to bulk scales. We primarily focus on experimental developments and their connections to continuum constitutive models. We first discuss small-scale planar compaction experiments which leverage x-ray imaging and time-resolved x-ray phase contrast imaging. These experiments are combined with digital twin modeling to quantify pore collapse, stress concentrations, and dynamic force chains in 3D at the grain scale. We then discuss penetration experiments at the bulk scale which employ flash x-ray imaging and a novel method of 3D flow field reconstruction. Bulk scale experiments are compared with a continuum constitutive model uniquely informed by other tests which quantify grain-scale processes such as a grain breakage. The audience will leave the talk with an appreciation of how in-situ imaging and analysis can be used to inform our understanding of and modeling capabilities for dynamic processes in granular materials.
Short bio
Ryan Hurley is an Associate Professor in the Department of Mechanical Engineering with a secondary appointment in the Department of Civil and Systems Engineering, and a Faculty Fellow of the Hopkins Extreme Materials Institute at the Johns Hopkins University (JHU). Before joining JHU in 2018, Ryan received his Ph.D. in Applied Mechanics from Caltech and worked as a postdoc in computational geomechanics at Lawrence Livermore National Laboratory. Ryan has received a 2017 Department of Energy’s Secretary’s Appreciation Award, a 2020 NSF CAREER Award, a 2021 Army Education Outreach Program’s Mentor of the Year Award, and a 2022 Air Force Office of Scientific Research (AFOSR) Young Investigator Program Award. Ryan’s research interests include studying the deformation and failure mechanisms of granular materials, rocks, and concrete using advanced experimental techniques, such as in-situ x-ray imaging and diffraction, constitutive modeling, and micromechanics.
Sandwiches are offered at the end of the seminar.
Practical information
- Informed public
- Free
Organizer
- Prof. Olga Fink (IMOS), Prof. Alexandre Alahi (VITA), Prof. Dusan Licina (HOBEL), Prof. Alain Nussbaumer (RESSLab)
Contact
- Ghassan Shahin