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 L05: Strength IFocus Recordings Available
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Chair: Camelia Stan, Lawrence Livermore Natl Lab Room: Anaheim Marriott Platinum 3 |
Tuesday, July 12, 2022 2:00PM - 2:15PM |
L05.00001: Multiphase Strength Coupled with Phase Change Kinetics in RMI Experiments on Tin Across the Beta-Gamma Boundary Michael Prime, Nathan R Barton, Justin L Brown, Patrick M Donovan, Saryu J Fensin, David R Jones, Calvin R Lear, Kevin N Love, Darby J Luscher, Daniel Martinez, Thao Nguyen, William Schill A series of impact-driven Richtmyer-Meshkov Instability (RMI) experiments were used to study multiphase strength, in the presence of phase change kinetics, in tin across the ambient beta phase and higher-pressure gamma phase. Two experiments at shock stresses of 4 and 6 GPa did not change phase, and the measured velocities were used to calibrate a strength model for the beta phase. As with all the experiments in this study, representative strain rates ranged from about 106 to 107 /second. An experiment shocked to 14 GPa overdrove the phase transition, was sensitive to strength in both phases, and was used to calibrate strength in the gamma phase, assuming independence from kinetics. Finally, the data from an experiment shocked to 11 GPa showed simultaneous indications of strength and slow kinetics of the beta-gamma phase change and was used solely for validation. Two sets of parameters for phase change kinetics, combined with the calibrated strength models, were checked against that 11 GPa data. The kinetics parameters came from two independent Bayesian calibrations that simultaneously fit various combinations of the multiphase strength, forward and reverse transition kinetics, anelasticity, and phase boundaries. Data used simultaneously in the fits included flyer plate data and ramp-release data from pulsed-power machines. The comparisons with the 11 GPa RMI data show that the multiphase strength was highly coupled with phase change kinetics and the equation of state. Combined experimental and modeling strategies for handling the complex, coupled problem will be discussed. |
Tuesday, July 12, 2022 2:15PM - 2:30PM |
L05.00002: Simple and deep surrogate models for Taylor cylinders and shaped charges Sky K Sjue, Kyle S Hickmann, Nga Thi Thủy Nguyen We characterize strength model sensitivities of Taylor cylinders and shaped charges using ensembles of simulations based on the FLAG hydrocode from Los Alamos National Laboratory. We apply singular value decomposition and neural networks, for regression and parameter estimation, based on simulations and experimental data. Results will be presented for the Preston-Tonks-Wallace and Johnson-Cook models of plastic deformation. |
Tuesday, July 12, 2022 2:30PM - 3:00PM |
L05.00003: Bayesian methods to extract cold curves from shockless compression experiments on the Z machine Invited Speaker: Justin L Brown Statistical methods are becoming ubiquitous in the data sciences and many of the advanced techniques are now being leveraged to better understand the results from dynamic material experiments. Here, we examine how velocimetry measurements in multi-megabar shockless compression experiments can be coupled to hydrocode simulations to constrain the reference isotherm in equation of state development. Bayesian inference is used to incorporate all known sources of error across multiple data sets for rigorous uncertainty quantification, while Monte Carlo methods are used to understand relative sensitivities. Unexpected problems with high-pressure sensitivity emerge when using conventional parametric model forms for the cold curve; a novel non-parametric model form is suggested as a better approach. Examples from materials with and without phase transformations including platinum compressed to 600 GPa and tin loaded to 120 GPa will be presented and compared to traditional analysis methods. |
Tuesday, July 12, 2022 3:00PM - 3:15PM |
L05.00004: Assessment of Heated Reverse Taylor Cylinder Experiments for the Calibration of Tantalum Strength Models Ben Thorington-Jones, Glenn Whiteman, Daniel Eakins, Dave Chapman, Liam Smith A series of heated reverse Taylor impact experiments using an improved experimental heating and alignment system have been undertaken with our partners at the University of Oxford. Multiple combinations of flyer velocity and temperature in the 100-200m/s and 300-1000K respective ranges were combined to probe the individual and interdependent effects of strain-rate and temperature on tantalum targets. This talk discusses the interpretation of the velocimetry and high speed photography data obtained, in comparison to Lagrangian hydrocode simulations, to assess the ability of existing strength models to capture the deformation behaviour of tantalum in these strain-rate and temperature regimes. A particular emphasis is put on assessing the performance of the PTW (Preston-Tonks-Wallace) strength model. UK Ministry of Defence © Crown Owned Copyright 2022/AWE. |
Tuesday, July 12, 2022 3:15PM - 3:30PM |
L05.00005: MD- and crystal-plasticity guided material models for HMX and RDX under shocks Oishik Sen, Garrett M Tow, Puhan Zhao, James P Larentzos, John K Brennan, Tommy Sewell, Catalin Picu, H.S. Udaykumar Meso-scale computations of the shock response of energetic materials with resolved complex microstructures (e.g., a PBX) often rely on isotropic models for computing the elasto-plastic response. Although robust and computationally efficient, these models rely on empirical model constants, which are not predictive outside of calibration intervals and have large uncertainties even for relatively well-characterized high explosives such as HMX and RDX. We develop isotropic models from single crystal plasticity computations of HMX and RDX under shocks. All-atom MD is used to guide the model and serves as the fundamental metric for validation. The continuum simulations are performed in an Eulerian framework that incorporates thermally activated and drag-regulated dislocation motion as well as dislocation multiplication, trapping and annihilation for heterogeneous nucleation. Ensembles of anisotropic single-crystal plane-strain simulations of RDX and HMX are performed to compute the von Mises stress behind the shock for different orientations and loading velocities, which are then averaged to calibrate Johnson-Cook and Steinberg-Guinan-Lund models for HMX and RDX. Meso-scale computations performed using those models are validated against MD simulations under different shock strengths. |
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