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 E05: Complex Loading of Soft MatterRecordings Available
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Chair: Rachel Huber, Los Alamos National Laboratory Room: Anaheim Marriott Platinum 3 |
Monday, July 11, 2022 2:00PM - 2:15PM |
E05.00001: Split Hopkinson pressure bar measurements of polymer energy dissipation and identification of the glass transition condition David M Williamson, Malvina Constantinou We explore the idea of using a split Hopkinson pressure bar to measure polymer energy dissipation. For an elastic specimen the sum of the mechanical energies within the transmitted and reflected pressure pulses ought to be equal to mechanical energy in the incident pressure wave. Any deficit is due to inelastic dissipation by the specimen. The amount of energy dissipated can be plotted as a function of temperature and will be greatest at the glass transition condition. Our results are discussed in the context of dynamic mechanical analysis data taken on the same polymer and the use of Group Interaction Modelling as a physical framework of understanding. |
Monday, July 11, 2022 2:15PM - 2:30PM |
E05.00002: Spall strength of polycarbonate measured using laser-driven micro-flyer impact experiments Jacob M Diamond, Kaliat Ramesh Polymers play an increasingly large role in application areas involving extreme loadings, from polymer-bonded explosives to personnel and vehicular protection systems. However, there remain substantial gaps in our knowledge of polymer mechanics at very high strain rates, especially regarding spall strength and dynamic void growth. Further, the underlying micromechanisms that control dynamic void growth and spall in polymers are not fully understood. Here we present experimental results on the spall strength of a model amorphous thermoplastic, polycarbonate, measured using laser driven micro-flyer (LDMF) plate impact and photonic Doppler velocimetry (PDV). Our experimental method enables high-throughput testing, such that we can collect an order of magnitude more data points than traditional gas gun spall experiments. This large volume of tests allows us to generate spall strength statistics, and to correlate spall response with material characteristics. The results presented here will serve as a basis for future efforts in modeling dynamic void growth and spall in amorphous polymers. |
Monday, July 11, 2022 2:30PM - 2:45PM |
E05.00003: Dynamic Strength of PDMS-Based Elastomers under Combined Pressure-and-Shear Impact Loading David B Bober, Matt Nelms, Vikas Prakash Filled elastomers are used in a variety of engineering applications from structural supports to impact mitigation protection. In rubbery elastomers, such as cross-linked polydimethylsiloxane (PDMS), silica and quartz fillers have been used to provide improved mechanical and creep properties. To-date, the strength of these materials at high strain rates and high pressures is poorly understood. In the present study, high-strain-rate pressure-shear plate impact (PSPI) experiments have been conducted to investigate the dynamic strength of two commercially available silicone elastomers, DC745U and Sylgard 184, the former containing a high filler content and the latter being unfilled. The goal is to better understand the effects of pressure, strain hardening, and strain rate sensitivity on their strength. The pressure range investigated is 0.75 to 3.6 GPa at shear strain rates up to 7x105/s. The flow stresses in both elastomers are observed to be highly pressure sensitive with the shear strengths of DC745U and Sylgard reaching 350 MPa and 280 MPa, respectively, at pressures ~ 3.6 GPa. Both elastomers show considerable strain hardening, the effect of which increases with increasing pressures. In contrast to the observed pressure and strain sensitivity, the strength appears nearly insensitive to strain rate within the pressure range investigated. |
Monday, July 11, 2022 2:45PM - 3:00PM |
E05.00004: Molecular-Dynamics Simulations and Laser-Drive Shock-Release Experiments on Polystyrene Under Inertial Confinement Fusion Conditions Shuai Zhang, Suxing Hu, Dayne E Fratanduono, Ryan Rygg, Michelle C Marshall, Amy E Lazicki, Alex Shvydky, Daniel J Haberberger, Valeri N Goncharov, Thomas R Boehly, Gilbert W Collins We report extensive studies of polystyrene (CH) shock release by large-scale molecular dynamics and laser-drive experiments.1,2 The simulations show species separation and H streaming ahead of C, preferentially for CH under strong shocks. Our experimental design prevents radiation preheating of the sample and employs a witness foil to investigate the release of shocked CH across a vacuum gap. We observed earlier acceleration of the foil under stronger shocks as well as reflectivity changes before the foil moved, which is consistent with the findings of our simulations that H streams ahead of C at the release front. Furthermore, our calculations show that lighter species or hydrogen isotopes can carry more mass by 1 to 2 orders of magnitude to farther distances during the release and that less than 0.1× thermal expansion (as predicted by hydrodynamics) is needed to explain the high velocities and scale lengths of low-density plasmas observed in radiation-preheated CH experiments.3,4 These results imply general occurrences of species separation in the shock release of compounds, which shall be considered and its potential effects shall be clarified in the design, interpretation, and analysis of future high-energy-density and inertial confinement fusion experiments. |
Monday, July 11, 2022 3:00PM - 3:15PM |
E05.00005: 1-D Method for Gram-Scale Performance Characterization of Explosive Materials Forrest R Svingala TBD |
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