Dynamic Behavior of Materials IX: Poster Session
Sponsored by: TMS Structural Materials Division, TMS: Mechanical Behavior of Materials Committee
Program Organizers: Eric Brown, Los Alamos National Laboratory; Saryu Fensin, Los Alamos National Laboratory; George Gray, Los Alamos National Laboratory; Marc Meyers, University of California, San Diego; Neil Bourne, University of Manchester; Avinash Dongare, University of Connecticut; Benjamin Morrow, Los Alamos National Laboratory; Cyril Williams, US Army Research Laboratory
Monday 5:30 PM
February 28, 2022
Room: Exhibit Hall C
Location: Anaheim Convention Center
Session Chair: Eric Brown, Los Alamos National Laboratory; Saryu Fensin, Los Alamos National Laboratory; Avinash Dongare, University of Connecticut; Benjamin Morrow, Los Alamos National Laboratory; Cyril Williams, Army Research Laboratory; Marc Meyers, University of California San Diego; George Gray, Los Alamos National Laboratory; Neil Bourne, The University of Manchester
G-4: An Improved Method for High Strain Rate Nanoindentation Testing Using Piezoelectric Load Cell Measurements: Christopher Walker1; Benjamin Hackett1; Sudharshan Pardhasaradhi2; Warren Oliver3; George Pharr1; 1Texas A&M University; 2ARCI; 3KLA Corporation
Traditional nanoindentation relies on careful calibration of an electromagnetic actuator to determine the load applied to the indenter tip and assumes no dynamic forces are applied to the sample. This assumption does not hold for high strain rate nanoindentation, where the applied force is dominated by dynamic contributions from high velocities and accelerations during the test. Time derivatives of the measured displacement can be used to calculate the dynamic contributions but drastically amplify noise in the load. Here, an investigation was conducted to determine if a piezoelectric load cell can be used to improve load on sample accuracy in a high strain rate nanoindentation system. It was found that the measured piezoelectric load mitigates noise issues but introduces new time constants that have important implications for the load-depth curves with physical relevance for material characterization. In turn, reduced noise in the load measurements can lead to more precise hardness measurements.
G-5: Atomistic Investigation of Stress Release Mechanisms of Aramid Fibers: Emily Gurniak1; Subodh Tiwari1; Aiichiro Nakano1; Rajiv Kalia1; Priya Vashishta1; Paulo Branicio1; 1University of Southern California
Molecular Dynamics simulations using the Multi-Scale Shock Technique are employed to investigate the deformation and failure mechanisms of poly(p-phenylene terephthalamide) polymer crystals under shock loading. Shock states are generated from the propagation of shock waves with velocity between 4.8 and 10.0 km/s along the [100] and [010] directions, perpendicular to the polymer backbone. Both cases display an elastic regime at low shock velocities and chain cross-linking at high velocities. The intermediate shock velocity regime for the [010] case, displays hydrogen bond scission leading to planar amorphization. In contrast, in the intermediate shock velocity regime for the [100] case, polymer sheets re-arrange preserving hydrogen bonds to form a new crystal structure. These results indicate hydrogen bond preserving (structural phase transformation) and nonpreserving (planar amorphization) shock release mechanisms are essential for understanding the shock performance of aramid fibers and composites such as Kevlar and Twaron.
G-7: Deformation Mechanism of Laser Direct Metal Deposited Cu-Fe Alloy under High Strain Rate Condition: Arya Chatterjee1; Wesley Higgins2; Ethan Sprague1; George Pharr2; Amit Misra1; 1University of Michigan; 2Texas A&M University
The present investigation aims to study the plastic deformation mechanism in an immiscible Cu-Fe alloy. The Cu-Fe alloy used in the current study showed the presence of two phases (i.e. Cu and Fe) in equal amounts in the microstructure. This Cu-Fe alloy is prepared using a laser direct metal deposition (DMD) based additive manufacturing (AM) technique and produces a hierarchical microstructure. The 50Cu-50Fe alloy is then subjected to plastic deformation at different strain rates. Nano-indentation technique is used to apply different constant strain rates (in the range of 10-3 /sec to 102 /sec) deformation and impact loading (with varying strain rates) to the Cu-Fe alloy. The post deformation damages specifically near the indented tip regions are studied with the help of scanning transmission electron microscopy (STEM-HAADF) to elucidate the underlying mechanism of deformation at different strain rates for hierarchical microstructure in a Cu-Fe alloy.
G-10: Dynamic Compressive Response of Hot-pressed Boron Carbide: Understanding the Role of Microstructural Heterogeneities: Arezoo Zare1; Amartya Bhattacharjee1; Qi Rong Yang2; Kent Christian2; Richard Haber2; Lori Graham-Brady1; Matt Shaeffer1; K.T. Ramesh1; 1Johns Hopkins University; 2Rutgers University
A combination of high hardness and low density makes boron carbide (B4C) desirable for ballistic applications. However, commercially available B4C ceramics typically contain a high number density of microstructural heterogeneities resulting from processing. Investigations of the dynamic response of B4C have highlighted the role of such microstructural heterogeneities (particularly carbonaceous inclusions) on the initiation/propagation of cracks. Understanding the effects of the size, spacing, and orientation of these inclusions on the dynamic response is thus essential for designing B4C with improved performance. In this study, a modified Kolsky bar setup is used to evaluate the dynamic compressive response of hot-pressed B4C specimens that contain different sizes/concentrations of carbonaceous inclusions, and the results are compared to expectations from existing models. Preferential orientation of the inclusions is also studied by testing the specimens either parallel or perpendicular to the hot-pressing direction. Fragments of the tested specimens are collected to examine their size/shape distributions.
NOW ON-DEMAND ONLY - G-12: Equibiaxial Strength Testing of Lithium Hydride: Gabriella King1; Christian Bustillos1; Wyatt Du Frane1; Joshua Kuntz1; 1LLNL
Lithium Hydride pellets of varying size and density were tested as per ASTM equibiaxial flexural strength testing methods (C1499-15). While bend tests and radial and uniaxial compression tests have been performed on LiH, this work is the first to explore it’s equibiaxial behavior. Hot pressed pellets were sintered at temperatures ranging from 150-550C, to map the effect of consolidation conditions on the equibiaxial strength of the material. To mitigate uneven point loading during trials, a compliant material with a Shore hardness of 60 was placed between fixturing and samples. Density and subsequent equibiaxial strength were found to increase with consolidation temperature. Initial fractographic analysis was performed on post-test fragments to analyze the fracture source for each test case, showing similar fractographic behavior for the range of components. (This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344)
G-14: High Strain-rate Strength Response of Single Crystal Tantalum through In-situ Hole Closure Imaging Experiments: Jonathan Lind1; Robert Carson1; Nicolas Bertin1; Matthew Nelms1; 1Lawrence Livermore Laboratory
The properties of crystalline materials often depend on directionality and operating conditions. Specifically, strength can depend anisotropically on crystal direction and loading condition. A preliminary series of high strain-rate (>105/s) plate-impact hole closure experiments were performed on high-purity single crystal Tantalum. The impact/loading condition and orientation of the single crystals were varied to provide data to inform crystal plasticity modeling efforts. The experiments consist of in-situ high-resolution radiographic imaging of the hole collapse under dynamic compression conditions to infer the material strength. The recovered samples are characterized with EBSD to evaluate the deformation structure that developed. ---This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, by the Dynamic Compression Sector supported by National Nuclear Security Administration under Award Number DE-NA0002442, used resources of the Advanced Photon Source at Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
G-15: In Situ Analysis of Shear Bands and Fracture in Metals: Shwetabh Yadav1; Harshit Chawla2; Dinakar Sagapuram2; 1Department of Civil Engineering, Indian Institute of Technology Hyderabad; 2Department of Industrial & Systems Engineering, Texas A&M University
Using in situ high-speed imaging, we study a failure mode in metals where localized plastic flow inside shear bands acts as a precursor to fracture. Plane-strain cutting is used as an experimental framework to impose large strain deformation under controlled rates of shear. A range of outcomes --- homogeneous flow, shear localized flow, to complete material separation --- is demonstrated using the same geometry by simply varying the shearing rate. Shear band initiation, inhomogeneous strain field development, and subsequent fracture dynamics are visualized in situ and quantitatively characterized using Particle Image Velocimetry. It is shown that a critical stress criterion governs the first transition from homogeneous flow to shear banding, whereas the localized flow to fracture transition seems to follow a strain-based rule. Implications for using cutting or “machining” as a rapid method to study the behavior of metals under extreme strains and strain rates are discussed.
G-16: Influence of Microstructure on Radial Expansion of 4340 SS Cylinders: Carl Trujillo1; Saryu Fensin1; George Gray1; 1Los Alamos National Laboratory
Expanding cylinder techniques are useful methods of investigating dynamic fracture properties under a wide range of strains and strain rates. In this study, a gas-gun technique is used to achieve uniform radial expansion of a cylinder. This expansion is driven by the impact of a polycarbonate projectile (velocities up to 1000m/s) impacting a stationary polycarbonate cylinder within the specimen cylinder. This study aims to understand the dynamic expansion and fragmentation of additively manufactured 4340 SS in comparison to wrought 4340 SS. A combination of in-situ diagnostics was used to measure strain, strain rates, and temperature: High Speed Imaging, Photon Doppler Velocimetry (PDV), Digital Imaging Correlation (DIC), and a High-Speed IR Camera. Post mortem microscopy of the specimen and fractured segments was also performed to understand differences in failure.
G-18: Modeling Shock Wave Propagation Using a Moving Window CAC Framework: Alexander Davis1; Vinamra Agrawal1; 1Auburn University
We develop two distinct moving window approaches within a Concurrent Atomistic-Continuum (CAC) framework to model shock wave propagation through a one-dimensional monatomic chain. In the first method, the entire domain follows the shock in a conveyor fashion, while in the second method, the fine-scaled region travels through the chain by the simultaneous coarsening and refinement of the continuum regions. The CAC domain and moving window methods are verified through dispersion relation studies and phonon wave packet tests. We achieve good agreement between the simulated shock velocities and the values obtained from theory with the conveyor technique, while the coarsen-refine technique allows us to follow the propagating wave front through a large continuum domain. This work showcases the ability of the CAC method to accurately simulate propagating shocks and also demonstrates how a moving window technique can be used in a multiscale framework to study highly nonlinear, transient phenomena.
G-19: Phase Transformation in Cu: Nilanjan Mitra1; 1Johns Hopkins University
No solid-solid phase transformation is considered in Cu. However, Cu based Hume-Rothery shape memory alloys exhibit body centric phase transformations at high temperatures. Atomistic simulations along with Gibbs free energy calculations within the quasiharmonic approximations to demonstrate phase transformation of Cu (FCC to BCT) subjected to high temperature and high pressure in shock compression experiments, as per previous postulation by Friedel. Recent experimental investigations carried by Gupta at WSU on polycrystalline Cu demonstrated presence of body centered phases (PRB (2020): 102, 020103(R)). At comparatively low shock speed, various line defect formations can be observed in Cu which can typically be classified as plasticity mechanism within the material (including observance of twining in Cu under shock compression as observed by Meyer at UCSD).
G-20: Polymer Mechanics under High Pressure: Jennifer Jordan1; Daniel Casem2; Eric Brown1; Blake Sturtevant1; 1Los Alamos National Laboratory; 2CCDC US Army Research Laboratory
High pressure mechanics of polymers have been studied using a variety of techniques, including Paris-Edinburgh press, diamond anvil cell, pressure-shear experiments and lateral manganin gauges in shock experiments. In the present work, we have studied a variety of polymers,including polyurea, polymethylmethacrylate (PMMA), polytetrafluroethylene (PTFE), and polyethylene (PE), to understand the relationship between polymer structure. We will present experimental studies to understand the high pressure elastic behavior using a Paris-Edinburgh press and ultrasonic sound speed measurements. Additionally, we will present dynamic high pressure results using longitudinal and lateral manganin gauges to determine the normal and shear stress in the polymers. We will compare our experimental results to those in the literature using other experimental techniques.
G-22: Mechanical and Structural Transformation of Titanium Containing Helium Bubbles: Sarah Stevenson1; Peter Hosemann1; Saryu Jindal Fensin2; 1University of California Berkeley; 2Los Alamos National Laboratory
The effects of Helium (He) accumulation in materials are of great interest to the nuclear community since He is produced from radionuclide transmutation and high energy neutron reactions. He is insoluble in almost all solids, and precipitates into nanometer sized bubbles which results in degradation of the mechanical properties of nuclear structural materials. Despite that He bubbles may significantly impact dynamic materials properties and processes, including high strain rate loading, studies along these lines are quite rare. This work investigates He bubbles in Titanium (Ti) samples with and without dynamic loading. Ti is implanted with He ions and then characterized using Transmission Electron Microscopy (TEM). Additional TEM investigation of He implanted and subsequent shock loaded samples is performed to characterize defect production as well as the restructuring and production of He bubbles resulting from shock loading, thereby addressing the dynamic properties of He bubbles.
G-23: Shock-driven Foamed Metals for Studying Shallow Bubble Collapse: Eric Stallcup1; Garry Maskaly1; Fady Najjar1; Gerald Stevens2; William Turley2; Brandon La Lone2; Matthew Staska2; 1Lawrence Livermore National Laboratory; 2MSTS Special Technologies Laboratory
Study of shock-driven ejecta has historically focused on Richtmeyer-Meshkov instability (RMI) growth as the primary mechanism, but a fundamentally different method, termed Shallow Bubble Collapse (SBC), has recently been established. If a material is shocked multiple times, SBC describes the process by which the release after first shock forms cavitation bubbles directly beneath the surface, and the second shock collapses these bubbles. This releases significantly more ejecta than that described by RMI. In this work, we isolate the cavitation bubble collapse and ejecta release process by shocking a porous aluminum foam with a strong single shock. This simplified problem allows for more control over the shock conditions and access to additional diagnostics during experimentation. We compare results with differences in pore size, morphology, and pore fraction. These experiments, supported by numerical simulation, have shown this method accurately reproduces the physical processes taking place in SBC, therefore enabling faster model development.