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 U04: Strength and Constitutive Behavior IIRecordings Available
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Chair: Saryu Fensin, Los Alamos Natl Lab Room: Anaheim Marriott Platinum 2 |
Thursday, July 14, 2022 11:00AM - 11:15AM |
U04.00001: Elucidating size effects on the yield strength of single-crystal Cu via the Richtmyer-Meshkov instability Mitchell A Wood, James Stewart, Joseph Olles Capturing the dynamic response of a material under high strain-rate deformation often demands challenging and time consuming experimental effort. While shock hydrodynamic simulation methods can aid in this area, a priori characterizations of the material strength under shock loading and spall failure are needed in order to parameterize constitutive models needed for these computational tools. Moreover, parameterizations of strain-rate-dependent strength models are needed to capture the full suite of Richtmeyer-Meshkov instability (RMI) behavior of shock compressed metals, placing an unrealistic demand for this training data solely on experiments. Herein, we sweep a large range of geometric, crystallographic, and shock conditions within molecular dynamics (MD) simulations and demonstrate the breadth of RMI character in Cu that can be captured from the atomic scale. Yield strength measurements from jetted and arrested material from a sinusoidal surface perturbation were quantified. These defect-free, single crystal Cu samples used in MD will overestimate strength, but the drastic scale difference between experiment and MD is highlighted by high confidence neighborhood clustering predictions of RMI characterizations yielding incorrect classifications. These results will be discussed in a broader context of multi-scale modeling where individual methods probe vastly different length and time scales. |
Thursday, July 14, 2022 11:15AM - 11:30AM |
U04.00002: Design studies of copper strength via Rayleigh-Taylor instability from directly laser-driven experiments at the OMEGA-EP laser facility Tom Lockard, Matthew P Hill, Yong-Jae Kim, James M McNaney, Hye-Sook Park, Philip D Powell, Robert E Rudd, Camelia V Stan, Damian C Swift We present the design of experiments conducted at the OMEGA-EP laser facility using face-on radiography to measure ripple growth in solid copper and other metals to understand their dynamic strength under high pressure and high temperature. Historically these ramp-compression experiments have been accomplished by releasing a reservoir of material from a laser driven hohlraum onto a target configuration of materials. Here the target containing the copper sample is directly irradiated by the laser. The ramp-compression is achieved by the laser pulse shaping. Strength is inferred from experimentally obtained measurements using face-on radiographic measurements of ripple growth which are then compared to simulated growth factors using different strength models. The copper was designed to follow two different loading paths to megabar pressures: first using a smooth ramp yielding a low-temperature adiabatic path; the other by first shocking to a given pressure and then accelerating it to create a high-temperature adiabat path. The design simulations were set up using a combination of 1D and 2D simulations and the growth factor calculated through an areal density integration method. |
Thursday, July 14, 2022 11:30AM - 11:45AM |
U04.00003: Understanding Evolution of Metal Microstructures during Dynamic Deformation at Atomic Scales and Mesoscales Avinash Dongare, Marco Echeverria, Avanish Mishra, Ke Ma The response of structural metallic materials under dynamic loading conditions is determined by the evolution of defects, their interaction with each other, and their evolution behavior that dictates the failure behavior. Understanding the different plasticity contributors in FCC, and BCC metals during various loading and unloading stages using experiments is a challenge due to the fast time scales of the processes at high strain rates. This talk will provide an overview of the current understanding of the shock response and identification of plasticity contributors that determine the dynamic (spall) strengths of FCC, BCC, and HCP microstructures as predicted using molecular dynamics (MD) simulations. The talk will highlight our new capabilities to characterize the deformation modes using virtual diffractograms and quantify the corresponding plasticity contributors using virtual texture analysis. Example simulations comprise shock loading and spall failure of FCC (Cu) and BCC (Ta, Fe) microstructures generated using MD simulations. The virtual characterization unravels the contributions of the deformation modes on the shifts, broadening, and splitting behavior of the various peaks/spots in the diffractograms for single crystal and polycrystalline Cu, Ta, and Fe, microstructures during shock loading and spall failure. This talk will also discusses combining a mesoscale modeling method “Quasi-coarse-grained dynamics” and virtual XRD to bridge the mesoscale gap in characterizing the plasticity contributions in FCC and BCC metals from slip, twinning, and phase transformation behavior. |
Thursday, July 14, 2022 11:45AM - 12:00PM |
U04.00004: Meso-Scale Simulations of the Deformation in Additively Manufactured 316L Stainless Steel Lattices Characterized with in-situ X-ray Phase Contrast Imaging Brittany Branch, Paul E Specht, Scott Jensen, Bradley Jared Additive manufacturing (AM) has enabled the realization of topologically optimized lattice architectures for lightweight structural components that provide superior mechanical properties and energy absorption capabilities compared to bulk materials and yet the property-to-performance relationship of these structures at high strain rates have not been experimentally characterized, therefore limiting the development of mesoscale modeling techniques to further understand the constitutive response of metallic lattices. Here, we present a methodology to parameterize the constitutive response of metal lattice architectures through coupling detailed mesoscale simulations that incorporate an as-built lattice characterized by computed tomography (CT) to shock compression experiments combined with in-situ x-ray phase contrast imaging (PCI). We compare PCI images to simulated radiographs generated from the mesoscale simulations to investigate the influence of the constitutive parameters for an octet lattice impacted in a velocity range of 0.8 – 1.2 km/s. The coupled approach offers a more robust method to validate and optimize constitutive properties in AM metal lattices through direct comparison of the transient deformation states and can be extended to other AM architectures. |
Thursday, July 14, 2022 12:00PM - 12:15PM |
U04.00005: Investigating Process-Structure-Property Relations of Shock Loaded Wrought and Additively Manufactured 304L Stainless Steel Christopher R. Johnson, Scott Alexander, Bernardo Farfan, John P Borg, Paul E Specht Comparative shock loading experiments were performed to investigate the dynamic response of ingot-derived wrought and additively manufactured (AM) SS304L stainless steel. Experiments looked to study how microstructural properties related to the fabrication process influence compression and release behavior. Sample variants were as-received wrought and as-built AM Z-Cut (build direction), as well as heat treated and recrystallized (1250oC) wrought and AM Z-Cut SS304L. Samples were loaded under identical loading conditions utilizing a forward-ballistic configuration, and interferometry measurements were performed utilizing photonic Doppler velocimetry (PDV). Impact velocities spanned 0.25-1.50 km/s, resulting in peak compressive stresses of 5-34 GPa. Waveform profiles were analyzed to determine Hugoniot elastic limits (HEL), shock-particle velocity relations, and shock-release measurements. Microstructural attributes, such as, grain size, morphology, and residual stresses are considered to explain similarities and differences in the experimental results. |
Thursday, July 14, 2022 12:15PM - 12:30PM |
U04.00006: Self-Similar Solutions of shock propagation in particle composite materials: Scaling dependence on particle drag and percolation models. Roger W Minich Self-similar solutions are solved for a shock propagation in a hydrodynamically coupled, two-phase media system using Lie group analysis. The composite media consists of a polymer matrix loaded with micron-sized spherical tungsten particles. Tuning both the particle diameter, Dp, and the particle volume fraction, f0, we find that the self-similar solutions depend on the form of the particle drag law and the constitutive material behavior as the spherical particle percolation limit is approached. We study the scaling behavior of the self-similar solutions for different drag and percolation scaling laws. We then compare our analysis with experimental velocity time histories for different tungsten loadings of the polymer matrix. |
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