Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session T5: Inelastic Deformations, Fracture and Spall X |
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Chair: Justin Brown, Sandia National Laboratories Room: Regency Ballroom B |
Thursday, July 13, 2017 11:15AM - 11:30AM |
T5.00001: Role of interfacial bonding in the design and realization of Magnetically Applied Pressure Shear (MAPS) experiments Jow Ding, C. Scott Alexander MAPS (Magnetically Applied Pressure Shear) is a new technique that can be used to explore the material behavior under dynamic compression-shear loadings at strain rates and pressures that are much higher than those that can be achieved by gas-gun driven pressure shear experiments. A significant challenge for MAPS is the transmission of large shear stress through material interfaces. In this study, numerical simulations were used to gain insights on the behavior of the interface between molybdenum, which is the driver, and zirconia, the anvil, in MAPS experiments. Molybdenum was stressed into the plastic regime and zirconia stayed elastic but appeared to have incurred some spall damage at the later stage of the experiments. By including damage for the anvil and interfacial sliding in the simulations, both the longitudinal and transverse velocity data were able to be reasonably simulated. The results indicate that the interfacial slip appears to usually occur at the beginning stage of the shear loading when the pressure is relatively low. After the pressure reaches a certain level, the shear stress could be fully transmitted. Some other possible experiment designs to minimize the role of interface in MAPS are discussed. [Preview Abstract] |
Thursday, July 13, 2017 11:30AM - 11:45AM |
T5.00002: Pressure-Shear Plate Impact experiments at pressures beyond 20 GPa Christian Kettenbeil, Michael Mello, Tong Jiao, Rodney Clifton, Guruswami Ravichandran Recent modifications of a powder gun facility at Caltech have enabled pressure-shear plate impact experiments (PSPI) in a regime of pressures and strain rates that were not accessible previously. Heterodyne fiber optic interferometers are adapted to simultaneously monitor normal and transverse particle velocity histories using a 400 line/mm diffraction grating deposited onto the polished rear surface of the target plate. A PDV measurement system interferes the $0^{th}$ order beam to probe the normal particle velocity, while a transverse PDV (TPDV) arrangement employs the $1^{st}$ order diffracted beams to extract the transverse velocity. Results are interpreted using a strength model developed through symmetric PSPI experiments beyond the Hugoniot elastic limit of the target plates. These developments have been driven by the desire to characterize material strength at pressures exceeding 20 GPa. We present initial findings of our work on the pressure-shear response of silica glass at nominal strain rates in the range of $10^{6}$ - $10^{7}$$s^{-1}$. [Preview Abstract] |
Thursday, July 13, 2017 11:45AM - 12:00PM |
T5.00003: Estimating and Interpreting an "Average'' Strength from Richtmyer-Meshkov Instability Experiments. Michael Prime Richtmyer-Meshkov Instabilities (RMI) have recently been used to estimate metal strength at strain rates of about 10\textasciicircum 7/s. RMI experiments involve shocking a metal interface with sinusoidal perturbations that invert, grow, and possibly arrest subsequent to shock in a way very sensitive to deviatoric strength. All published RMI-based strength estimates report a strength averaged over the duration of the experiment interrogated by the diagnostic. Since strain, strain rate, temperature and pressure all affect strength and all vary in the experiment, what does ``average'' strength mean, and is it useful for calibrating a high-rate constitutive model? In this study, we use a series of numerical simulations to establish the regimes and extent of those variables to which the instability is most sensitive. We assess assigning the strength estimate to a point in (strain, strain rate, temperature, pressure) space and using that in to aid in calibration of a strength model. We then apply the findings to experimental RMI data on copper at five different perturbation sizes so we can attempt to fit a PTW constitutive model and reproduce the data. Finally we compare the estimate of average strength to other estimates of high-rate strength in copper. [Preview Abstract] |
Thursday, July 13, 2017 12:00PM - 12:15PM |
T5.00004: Results of tantalum Rayleigh-Taylor strength experiments at high pressure and high strain rates on NIF and Omega H. -S. Park, N. R. Barton, R. M. Cavallo, C. M. Huntington, J. M. McNaney, B. A. Remington, R. E. Rudd, P. D. Powell, S. Prisbrey, D. C. Swift, C. E. Wehrenberg, A. Arsenlis Understanding the high pressure, high strain rate plastic deformation dynamics of materials is an area of research of high interest to a number of fields, including meteor impact dynamics and advanced inertial confinement fusion designs. Developing predictive theoretical and computational descriptions of such systems, however, has been a difficult undertaking. We have performed many strength experiments on Omega [1] and NIF to test Ta strength models at high pressures (up to 8 Mbar), high strain rates (\textasciitilde 10$^{\mathrm{7}}$ s$^{\mathrm{-1}})$ and high strains (\textgreater 30{\%}) under ramped compression condition using Rayleigh-Taylor instability properties. Our studies show that the work hardening dominates in this regime. We will describe the experimental results of the high pressure plastic deformation dynamics of tantalum from Omega and NIF in comparison with the various strength models including Livermore Multiscale Model [2]. [1] H. --S. Park et al., Phys. Rev. Lett. 114, 065502 (2015). [2] N. Barton, et al., J. App. Physics, 109, 073501 (2011). [Preview Abstract] |
Thursday, July 13, 2017 12:15PM - 12:30PM |
T5.00005: Measurements of Rayeigh-Taylor growth in solid and liquid copper in the Mbar regime J. M. McNaney, A. Arsenlis, C. M. Huntington, H.-S. Park, S. Prisbrey, B. A. Remington, D. C. Swift, C. E. Wehrenberg Face-on radiographic measurements of ripple growth in solid and liquid copper have been performed at the OmegaEP laser facility. Pre-imposed ripples of 80\textmu m wavelength were accelerated by the stagnation of a releasing shocked polyimide ``reservoir'' which was directly driven by 4-9kJ of laser energy. The state of the copper was varied from solid to liquid by increasing the initial shock amplitude of the loading wave from below to above the Hugoniot shock-melting limit. A comparison with 2-dimensional hydrodynamic simulations indicates that growth in the solid phase is consistent with a strength roughly 1-3x that predicted by the commonly used Steinberg-Guinan model while growth in the liquid phase is consistent with little or no material strength. [Preview Abstract] |
Thursday, July 13, 2017 12:30PM - 12:45PM |
T5.00006: Modeling of Laser-Driven High-Rate Deformation of BCC Tantalum and Lead Robert Rudd, A. Arsenlis, R. M. Cavallo, J. McNaney, S. T. Prisbrey, B. A. Remington, C. E. Wehrenberg, H.-S. Park, P. Graham Multiscale strength models for high-rate deformation have been developed for tantalum and other metals starting with atomic bonding and extending up through the mobility of individual dislocations, the evolution of dislocation networks and so on until the ultimate material response at lab scale. This LMS model [1] can be run in continuum simulations. High-energy laser platforms such as the National Ignition Facility can probe plasticity at extremely high rates in largely shock-free ramp-compression waves. [2] Experiments on Ta at pressures of \textasciitilde 1 Mbar and strain rates of \textasciitilde 10$^{\mathrm{7}}$/s agreed well with the LMS model. [3-4] We examine recent results that suggest the reliance of the model on a simple pressure scaling based on the shear modulus is not sufficient in the range 3.5-5.0 Mbar. We also discuss a simpler strength model for the body-centered cubic (BCC) phase of lead in the range 3.5-5.0 Mbar. [1] N.R. Barton et al., J. Appl. Phys. \textbf{109}, 073501 (2011). [2] R.E. Rudd et al., MRS Bulletin \textbf{35}, 999 (2010). [3] H.-S. Park et al., Phys. Rev. Lett., \textbf{114}, 065502 (2015). [4] R.E. Rudd et al., AIP Conf. Proc. \textbf{1793}, 110004 (2017). [Preview Abstract] |
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