A System for In-Situ Studies of the Contact Mechanics Between Geomaterials
Abstract
The mechanical behavior of interfaces between rough surfaces plays a crucial role in determining the behavior of geomaterials, controlling force-displacement laws between grains, static and dynamic friction, thermal and electrical conductivity, and wear and damage during sliding. The behavior of rough interfaces also broadly dictates the longevity of industrial equipment subjected to frequent friction and wear. Despite numerical, theoretical, and experimental efforts, many fundamental challenges in the study of rough interfaces remain unresolved. These include: measuring the in-situ evolution of real contact area during compression, shear, and twist on interfaces between two rough materials; determining the micro- and nanoscale nature of asperity deformation, interaction, real contact area, and inter-asperity void morphology; linking the evolution of real contact area to normal and shear compliances; unraveling the effects of humidity and creep on interfacial mechanics. In this DURIP, a novel loading frame for compression, shear, and twist of two contacting geomaterial surfaces is proposed to address these issues. The loading frame will be amenable to a broad range of in-situ laboratory and synchrotron X-ray measurements, including: (1) force- and torque-displacement measurements; (2) ultrasound measurements of contact stiffness; (3) optical measurements of real contact area at the microscale; (4) synchrotron ptychographic X-ray tomography measurements of asperity morphology and deformation at the nanoscale; (5) synchrotron 3D X-ray diffraction measurements of stress fields beneath contact interfaces at the nanoscale. The loading frame will be complemented by a humidity control unit and a surface profilometer. The system will be used in future research projects to address the specific unresolved challenges described above and to complement the PIÕs current research on granular mechanics. Results from these research projects will facilitate advances in the field of contact mechanics, the development of physics-based discrete element method models for granular materials, and training of graduate students and postdoctoral researchers. These efforts and advances will support the ArmyÕs interests in modeling the mechanical behavior of various geomaterials (sands, soils, rocks) with a broad range of morphological features, moisture and thermal contents and their interaction with man-made structures and vehicles.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 06, 2019
- Source ID
- W911NF1910261
Entities
People
- Ryan C. Hurley
Organizations
- Army Contracting Command
- Johns Hopkins University
- United States Army