A5046659976- High-pressure geophysics and materials
- High-Velocity Impact and Material Behavior
- Microstructure and mechanical properties
- Electrohydrodynamics and Fluid Dynamics
- Laser-Plasma Interactions and Diagnostics
- Fluid Dynamics and Heat Transfer
- Metal and Thin Film Mechanics
- Force Microscopy Techniques and Applications
- Aluminum Alloys Composites Properties
- Mass Spectrometry Techniques and Applications
- Granular flow and fluidized beds
- Particle Dynamics in Fluid Flows
- Microfluidic and Bio-sensing Technologies
- Metal Alloys Wear and Properties
- Diamond and Carbon-based Materials Research
- Combustion and Detonation Processes
- Magnetic and Electromagnetic Effects
- Microstructure and Mechanical Properties of Steels
- Advanced materials and composites
- Cellular Mechanics and Interactions
- Scientific Computing and Data Management
- High voltage insulation and dielectric phenomena
- Structural Response to Dynamic Loads
- High Entropy Alloys Studies
- High Temperature Alloys and Creep
Lawrence Livermore National Laboratory
2015-2023
Washington State University
2020
Irvine University
2015-2017
University of California, Irvine
2015-2017
Duke University
2011
Swarthmore College
2008
Abstract Pulsating cone-jets occur in a variety of electrostatic spraying and printing systems. This paper reports an experimental study the pulsation frequency to reconcile two models based on choked jet oscillating cone, respectively. The regimes are demarcated by ratio supplied flow rate ( ${Q}_{s} $ ) minimum ${Q}_{m} required for steady Taylor cone-jet. When \lesssim {Q}_{m} , electrohydrodynamic is at nozzle because intermittent jet, when on, emits mass rate; regime proportional / ....
Abstract We report on fabrication and characterization of layered, tungsten doped, spherical about 2 mm diameter microcrystalline diamond ablator shells for inertial confinement fusion (ICF) experiments at the National Ignition Facility. As previously reported, ICF can be fabricated by chemical vapor deposition (CVD) solid silicon mandrels using an ellipsoidal microwave plasma reactor. In present work, we further developed these embedding a W -doped layer sandwiched between two undoped...
In the past decade, high throughput screening (HTS) has changed way biochemical assays are performed, but manipulation and mechanical measurement of micro- nanoscale systems have not benefited from this trend. Techniques using microbeads (particles ∼0.1–10 μm) show promise for enabling measurements microscopic systems. We demonstrate instrumentation to magnetically drive in a biocompatible, multiwell magnetic force system. It is based on commercial HTS standards scalable 96 wells. Cells can...
Dynamic compression of composite materials is scientific interest because the mechanical mismatch between internal phases challenges continuum theories. Typical assumptions about steady wave propagation and quasi-instantaneous state changes require reexamination along with need for time-dependent models. To that end, data models are presented shock an idealized particulate composite. serve as a generic representative this material class, polymer matrix was filled tungsten particles, ranging...
Experiments were performed on grooved Sn and Cu samples to study the temporal evolution of microjets. Jets generated by impact gun-launched flyer plates against back targets made from either or (groove depth ∼250 μm). The Hugoniot states in various encompassed conditions where solid phases are maintained throughout (7 16 GPa) also melting occurs upon release compression (25 34 GPa); transition near a pressure 23 GPa. at 27 56 GPa provide comparisons which jets move similar speeds but remain...
When a shock wave enters heterogeneous material, local differences in density and compressibility drive pressure velocity gradients which can be nearly as sharp the incident shock. Subsequent momentum equilibration is comparatively slow, relying on reverberation, particle collisions, shear flow. The latter phenomenon depends constitutive behavior that often poorly known so process problematic to simulate. This compounded by fact conventional diagnostics, such velocimetry, blend response of...
Solid particles can be fragmented by a fast-moving fluid if their velocity difference is great enough, such as during the atmospheric entry of meteoroids or shock compression engineered particulate composites. The extent particle deformation and breakup in systems poorly understood because necessary extreme conditions make observation difficult data scarce. To meet this need, experiments combining ultrafast synchrotron-based radiography with plate impact loading were performed at dynamic...
In situ x-ray diffraction was performed on shock-generated microjets composed of Sn and Sn–4Ag. Under low pressure drives (∼21 GPa), a significant fraction the jet volume found to be in β-Sn phase, these crystallites were much smaller than initial grain size material. Significant quantities amorphous (molten) material observed for higher drive pressures (∼25–35 GPa). The extent melting at greater would predicted uniaxial shock loading. Diffraction patterns from Sn–4Ag alloy showed peak that...
Counting and sizing particles necessary in many fields from metallurgy to biology is commonly done with solid sensing apertures that suffer seriously clogging. Physicists at Duke University take a drastically different approach build clogging-free particle counter liquid bridges or jets.
Abstract
Investigations of shock compression heterogeneous materials often focus on the front width and overall profile. The number experiments required to fully characterize dynamic response a material belie structure–property relationships governing these aspects wave. Recent observations measured pronounced shock-front order 10 s ns in particulate composites. Here, we composites with disparate densities investigate whether mechanical interactions between phases are adequate describe this emergent...
If microstructure affects the shock response of particulate composites, then it follows that microstructural changes occur during loading will affect subsequent release/reshock behavior. While a composite's initial is easily measured, there currently little information on how evolves once shocked. Using model polymer-tungsten composite, high speed radiography was used to collect in situ images changing particle shapes. These show isolated 50 µm tungsten spheres responded stresses imposed by...
Grain boundary networks should play a dominant role in determining the mechanical properties of nanocrystalline metals. However, these are difficult to characterize and their response deformation is incompletely understood. In this work, we study grain network Ni explore whether it can be modified by plastic deformation. Mechanical cycling at room temperature did not lead structural evolution, but elevated alter network. addition mechanically-driven growth, 100 $°$C led 48% increase $Σ$3...