Bulletin of the American Physical Society
22nd Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 67, Number 8
Monday–Friday, July 11–15, 2022; Anaheim, California
Session J05: Viscosity IFocus Recordings Available
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Chair: Arianna Gleason, SLAC - Natl Accelerator Lab Room: Anaheim Marriott Platinum 3 |
Tuesday, July 12, 2022 11:00AM - 11:30AM |
J05.00001: Dynamic viscosity of shock-compressed hydrocarbons (CH) Invited Speaker: Jessica Shang The mixing and transport of fluids at high pressures and temperatures can be found in applications ranging from planetary interiors to inertial confinement fusion. However, despite the role that viscosity has on the formation and growth of hydrodynamic instabilities and turbulence, experimental measurements of viscosity of materials at high energy-density conditions are limited in parameter space, since few conventional viscometry techniques can be applied in this regime. Even at moderately high pressures, experimental viscosity values may disagree by several orders of magnitude. In this talk, we describe ongoing experimental and modeling campaigns at OMEGA and EP that use two different techniques to determine the dynamic viscosity of dynamically-compressed fluids, where viscous effects are expected to be felt at similar scales. In the first technique, we use x-ray radiography to measure the displacement of impulsively accelerated spheres in solid epoxy, and corroborate the particle trajectory with unsteady forcing models to obtain the epoxy's dynamic viscosity from viscous force contributions. In the second technique, viscosity will be deduced by measuring the decaying oscillations of a rippled shock front in polystyrene with VISAR. Determining the magnitude of viscosity will improve hydrodynamic modeling for these complex systems and guide the development of particle-based velocimetry. |
Tuesday, July 12, 2022 11:30AM - 11:45AM |
J05.00002: Viscous Effects in Shock-Particle Interaction Afreen Syeda, Jessica Shang, Hussein Aluie, Nitish Acharya, Arianna Gleason, Danae Polsin, Riccardo Betti, Ryan Rygg, Gilbert W Collins, John J Ruby, Hadley Pantell, Alex Chin Viscosity gives insight into the momentum transport in a system and plays a crucial role in mixing and growth of hydrodynamic instabilities. Viscosity measurements in High Energy Density (HED) states are particularly important to accurately develop hydrodynamic models and to bridge the gap between simulations and experimental results of complex systems such as Inertial Confinement Fusion. We measured viscosity in dynamically compressed epoxy (CH, 1.1 g/cc) by tracing the acceleration of particles embedded in the target. The OMEGA-60 laser facility was used to generate laser beams to drive a shock (⁓240 GPa) through the CH target, which was embedded with 40 and 60 μm stainless steel spherical particles (7.8 g/cc) that would be accelerated by the flow behind the shock. The particle positions were recorded with time-resolved X-ray radiography. The shock speed was measured using VISAR and the velocity of CH was calculated from this data. The velocities of the particles and CH were used to determine the viscous and inviscid force contributions acting on the particles using a shock-particle forcing model. From the viscous unsteady force, we determined the dynamic viscosity of shock compressed CH to be ranging from 0 to 100 Pa.sec. |
Tuesday, July 12, 2022 11:45AM - 12:00PM |
J05.00003: Growth of Richtmyer–Meshkov Instability in Water Tamped Copper Joseph D Olles, Matthew C Hudspeth, Christopher F Tilger, Tracy J Vogler The Richtmyer–Meshkov instability (RMI) arises at an impulsively accelerated interface between two materials of different density. Previous work showed material strength at high strain-rates in solids can extracted from the amplitude and growth of the RMI spike in an untamped environment (metal-vacuum) and in a distended tamping media (metal-porous solid). Here, a bridge to understanding the nonlinear mechanical behavior of copper into a water is investigated experimentally and computationally. Data collected from the tamped liquid environment range in metal breakout pressures up to ten GPa. Results shows the RMI growth rate and profile are dependent on initial shock strength, as well as the nondimensional perturbation, with an initial Atwood number of −0.78. The oscillatory shock front in water is used to approximate the viscosity from a transient 1-D analytic approximation. The viscosity is found to be in agreement with other experimental work, however is not determined to be the only dissipative force in the experiment. Hydrocode simulations of our experiments show reasonable alignment with current and previously published work. |
Tuesday, July 12, 2022 12:00PM - 12:15PM |
J05.00004: Dynamic compression behavior of composite media with varying “microstructural” conditions Mukul Kumar A significant body of work has developed for the case of dynamic compression response of polycrystalline and multi-phase alloy microstructures. The experimental studies have been augmented by constitutive laws that describe the flow behavior under these high strain rate, high pressure loading conditions. Composite media with constituents that do not chemically interact with each other have been less frequently studied, though they have importance where multi-functionality can only be introduced through artificial means. We will compare the volumetric response of polymer-metal composite microstructures using free-surface velocimetry measurements. As an analog with multiphase alloys, the effects of a length scale encoded in particle volume fraction and size will be elucidated. This will be discussed in the context of processes such as internal wave reverberation, multiphase drag, and particle-particle force transfer that determine the rate of compression in a shock deformed particulate composite. |
Tuesday, July 12, 2022 12:15PM - 12:30PM |
J05.00005: Experimental Investigation and Modeling of the Dynamic Behavior of as-built SLM AlSi10Mg Sara Ricci, Nicola Bonora, Gianluca Iannitti, Gabriel Testa AlSi10Mg alloy is a commonly used material in AM processes and there has been a great effort to investigate its microstructure, the influence of process parameters and post-treatments, and its quasi-static and fatigue response. However its mechanical behavior under extreme conditions has yet to be assessed. In this work, a thorough investigation of as-built SLM AlSi10Mg mechanical behavior and constitutive modeling are presented. Quasi-static and dynamic tests on smooth and round notched bars, and shear tests were performed and the influence of three different building orientation (0°, 45° and 90°) was considered. Dynamic Tensile Extrusion (DTE) and Taylor Cylinder Impact (TCI) tests, under different impact velocities, were used to probe the material response and fracture behavior under complex load paths, large plastic deformations, and high strain rates and temperatures. From the experimental data, an appropriate yield criterion, constitutive and damage models were selected and validated by the numerical simulation of both DTE and TCI tests. |
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