Optically recording velocity interferometer system configurations and impact of target surface reflectance properties [Invited]

Cooper, Marcia A.

doi:10.1364/ao.53.000f21

Cited by 3 publications

(1 citation statement)

References 17 publications

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“…The primary diagnostic used in these experiments was the line-VISAR [26,27], an optical interferometer that can resolve velocity histories along a narrow line. The line-VISAR was oriented perpendicular to the perturbation peaks as shown in Fig.…”

Section: Experimental Configurationmentioning

confidence: 99%

Shock Wave Perturbation Decay in Granular Materials

Vogler

2015

J. dynamic behavior mater.

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A technique in which the evolution of a perturbation in a shock wave front is monitored as it travels through a sample is applied to granular materials. Although the approach was originally conceived as a way to measure the viscosity of the sample, here it is utilized as a means to probe the deviatoric strength of the material. Initial results for a tungsten carbide powder are presented that demonstrate the approach is viable. Simulations of the experiments using continuum and mesoscale modeling approaches are used to better understand the experiments. The best agreement with the limited experimental data is obtained for the mesoscale model, which has previously been shown to give good agreement with planar impact results. The continuum simulations indicate that the decay of the perturbation is controlled by material strength but is insensitive to the compaction response. Other sensitivities are assessed using the two modeling approaches. The simulations indicate that the configuration used in the preliminary experiments suffers from certain artifacts and should be modified to remove them. The limitations of the current instrumentation are discussed, and possible approaches to improve it are suggested.

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Section: Experimental Configurationmentioning

confidence: 99%

Shock Wave Perturbation Decay in Granular Materials

Vogler

2015

J. dynamic behavior mater.

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Imaging perturbed shock propagation in powders

Cooper

Sapp

Guo

et al. 2020

Review of Scientific Instruments

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A novel experimental methodology is presented to study the deviatoric response of powders in shock regimes. The powders are confined to a cylindrical wedge volume, and a projectile-driven shock wave with a sinusoidally varying front propagates through the powder. The perturbed shock wave exhibits a damping behavior due to irreversible processes of viscosity and strength (deviatoric) of the powder with propagation through increasing powder thicknesses. The inclined surface of the wedge is polished and coated to establish a diffuse surface suitable for reflecting incident laser light into a high-speed camera imaging at 5 MHz. Images of the contrast loss upon shock wave arrival at the observation surface are post-processed for qualitative and quantitative information. New data of shock damping behavior with parameters of perturbation wavelength and initial shock strength are presented for powders of copper, tantalum, and tungsten carbide as well as their mixtures. We present the first full-field images showing additional spatial disturbances on the perturbed shock front that appear dependent on particle material and morphology.

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Quantifying particle-scale 3D granular dynamics during rapid compaction from time-resolved in situ 2D x-ray images

Gupta

Crum

Zhai

et al. 2021

Journal of Applied Physics

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Understanding the particle-scale dynamics of granular materials during rapid compaction and flow is of fundamental importance for manufacturing, planetary science, geology, and defense applications. Time-resolved 2D radiography and static 3D x-ray tomography are powerful in situ tools for studying particle-scale dynamics but provide detail only in 2D or with significant time-scale limitations, respectively. Here, we introduce a new method that uses 2D in situ x-ray imaging for determining time-resolved 3D particle-scale dynamics in rapidly compressed granular materials. The method employs initial particle packing structures obtained from x-ray tomography, a 2D x-ray image generation algorithm, and an optimization algorithm. We first describe and validate the method using finite element simulations. We then apply the technique to x-ray phase-contrast images obtained during rapid compaction of granular materials with varying particle morphology and sample thickness. The depth-resolved particle-scale dynamics reveal complex velocity and porosity fields evolving heterogeneously along and perpendicular to the compaction direction. We characterize these features, their fluctuations near the compaction front, and the compaction front thickness. Our technique can be applied to understanding granular dynamics during rapid compaction events, and rearrangements during slower, but non-quasi-static, flows.

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Optically recording velocity interferometer system configurations and impact of target surface reflectance properties [Invited]

Cited by 3 publications

References 17 publications

Shock Wave Perturbation Decay in Granular Materials

Shock Wave Perturbation Decay in Granular Materials

Imaging perturbed shock propagation in powders

Quantifying particle-scale 3D granular dynamics during rapid compaction from time-resolved in situ 2D x-ray images

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