Bulletin of the American Physical Society
21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 64, Number 8
Sunday–Friday, June 16–21, 2019; Portland, Oregon
Session R5: PPCM: Porous Rocks |
Hide Abstracts |
Chair: D. Anthony Fredenburg, LANL Room: Broadway I/II |
Thursday, June 20, 2019 9:15AM - 9:45AM |
R5.00001: Characterization and Modeling of Compaction Damage from Shaped Charge Jet Penetration in Saturated Geomaterials Invited Speaker: Andrew Seagraves In oil and gas wells, shaped charges are used to establish a connection between the wellbore and the formation rock. During the penetration event, a localized zone of damaged material is created around the perforated tunnel which plays a dominant role both in well stimulation and in the eventual production of oil from the reservoir. In recent injection flow experiments on perforated limestone cores we have systematically characterized the permeability of the damaged zone and shown that it depends on both the initial permeability of the rock and on pore fluid properties. The present study aims at understanding the basis for these trends through a combined experimental and numerical investigation. To this end, large-format thin sections are prepared at multiple cross sections along the perforation tunnel and are digitized with a petrographic microscope. Novel segmentation and image analysis algorithms reconstruct the spatial variation of pore-scale properties throughout the damaged zone. In limestone, we find that damage is dominated by collapse of the pore network resulting in a compacted region with strongly reduced porosity near the edge of the tunnel. The mechanisms of compaction damage are then explored in hydrocode simulations of planar impact on a 2-dimensional meso-scale model of limestone with a synthetic pore network. The simulations attempt to explicitly capture the process of pore collapse and clarify the influence of pore network and fluid properties on the resulting compaction pattern. [Preview Abstract] |
Thursday, June 20, 2019 9:45AM - 10:00AM |
R5.00002: Shock Compaction of Cortuf -- an Ultra High Performance Concrete Christopher Neel Several dozen impact experiments were conducted utilizing gun-driven, parallel-plate impacts in several complimentary configurations to produce weak shock waves in an Ultra-High Performance Concrete (UHPC) known as ``cortuf'' with no fiber reinforcement or coarse aggregate. This investigation shows that although different grades of concrete vary widely in quasi-static compressive strength, under dynamic shock loading (uniaxial strain), most have similar yield points that can be described as yield strength of 0.4 GPa. In cortuf, the dynamically determined compressive yield point agrees closely with the quasi-statically determined yield (in conditions of uniaxial strain), implying very little strain-rate strengthening in UHPC, but in low strength (conventional) concrete, the dynamically determined yield is much higher than the corresponding quasi-static yield point. Therefore, the yield point of concrete in high-rate uniaxial strain is found to be independent of unconfined yield strength, and limited to an upper bound of \textasciitilde 0.4 GPa (HEL$=$0.5 GPa). Post-yield compaction is strain-rate dependent in cortuf as well as other formulations for which literature data is available. The Hugoniot up to 21 GPa is reported, and the results suggest that Portland-cement-based concretes without fiber reinforcement display shock behavior below 3 GPa which is dependent on the formulation and curing, but above 3 GPa, \textit{most} can be represented by the empirical shock relation U$_{\mathrm{S}}=$2.35 km/s $+$1.66u$_{\mathrm{P}}$ to at least 21 GPa. [Preview Abstract] |
Thursday, June 20, 2019 10:00AM - 10:15AM |
R5.00003: Uniaxial Wave Propagation Through Copper Mountain Sandstone Nathaniel Helminiak, John Borg Copper Mountain sandstone samples of thickness varying from 0.6 mm to 2.5 mm, were tested in plane strain and pressure-shear configurations at impact velocities from 50 m/s to 200 m/s. Each plane strain test contained multiple sandstone samples so that differences in thickness can be compared any given shot. The particle velocity induced at the back surface of the sample was measured using a particle velocity velocimeter (PDV) system. Thus, the variations wave development as a function of sample thickness can be assessed. Pressure-shear experiments were performed in order to determine the strength characteristics of the sandstone samples. The dynamic experiments were simulated utilizing Peridigm and CTH and compared with experimental results. [Preview Abstract] |
Thursday, June 20, 2019 10:15AM - 10:30AM |
R5.00004: Finite element analyses of a granular assembly under projectile loading incorporating computed tomography imaging and damage mechanics Anne Turner, Aashish Sharma, Dayakar Penumadu, Eric Herbold Granular materials can provide protection from projectile weapons, and understanding the physics behind penetrating these materials allows military artillery to successfully reach adversaries seeking sanctuary within deeply buried targets. The penetration depth of a projectile is determined by the strength and deformation behavior of the granular material, which is affected by fracture of individual grains within the granular assembly. Interparticle forces, leading to contact stresses and ultimately fracture initiation, are influenced by particle morphology. A numerical method incorporating both particle fracture and morphology can provide a more accurate model of projectile penetration. In this research, a numerical approach utilizing high resolution x-ray computed tomography (CT) to incorporate grain morphology and an explicit finite element code which includes damage mechanics for simulating grain fracture is used to analyze an assembly of Ottawa sand particles subjected to projectile penetration. A small granular assembly of CT imaged Ottawa sand particles is analyzed under projectile loading with and without incorporating damage mechanics to investigate the initiation of particle fracture and its effect on the projectile's depth. This approach can then be used to create multi-scale models of granular assemblies under projectile loading considering the effect of individual particle shape and fracture on the penetration response through well calibrated numerical simulations. [Preview Abstract] |
Thursday, June 20, 2019 10:30AM - 10:45AM |
R5.00005: The effect of grain-scale properties on ballistic penetration into sand James Perry, Chris Braithwaite, Nick Taylor, Andrew Jardine The dynamics of granular materials depend on the complex network of inter-grain force chains, but a coherent understanding of the effects of grain-scale properties (morphology, moisture) and loading conditions (rate, geometry) is still lacking. Here, we impact cylindrical targets with spherical projectiles and employ Digital Speckle Radiography to determine both penetration depth and sand bed displacement during impact. We compare several similar silica sands under dry and moist conditions, and illustrate how – and why – very small variations in material properties can dramatically alter the stopping power of a granular bed. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700