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  • 1. Three-dimensional full-field velocity measurements in shock compression experiments using stereo digital image correlation

    Description:
    Shock compression plate impact experiments conventionally rely on point-wise velocimetry measurements based on laser-based interferometric techniques. This study presents an experimental methodology to measure the free surface full-field particle velocity in shock compression experiments using high-speed imaging and three-dimensional (3D) digital image correlation (DIC). The experimental setup has a temporal resolution of 100 ns with a spatial resolution varying from 90 to 200 μm/pixel. Experiments were conducted under three different plate impact configurations to measure spatially resolved free surface velocity and validate the experimental technique. First, a normal impact experiment was conducted on polycarbonate to measure the macroscopic full-field normal free surface velocity. Second, an isentropic compression experiment on Y-cut quartz–tungsten carbide assembly is performed to measure the particle velocity for experiments involving ramp compression waves. To explore the capability of the technique in multiaxial loading conditions, a pressure shear plate impact experiment was conducted to measure both the normal and transverse free surface velocities under combined normal and shear loading. The velocities measured in the experiments using digital image correlation are validated against previous data obtained from laser interferometry. Numerical simulations were also performed using established material models to compare and validate the experimental velocity profiles for these different impact configurations. The novel ability of the employed experimental setup to measure full-field free surface velocities with high spatial resolutions in shock compression experiments is demonstrated for the first time in this work.
    Keyword:
    Stereo Digital image correlation, Shock Compression, Full-field measurements, and High Speed imaging
    Subject:
    Applied Science and Engineering
    Creator:
    Ravindran, Suraj , Gandhi, Vatsa , Ravichandran, Guruswami , and Joshi, Akshay
    Owner:
    n.sakthivel@jioinstitute.edu.in
    Publisher:
    American Institute of Physics
    Location:
    United States
    Language:
    English
    Date Uploaded:
    21-03-2023
    Date Modified:
    21-03-2023
    Date Created:
    01-02-2023
    Rights Statement Tesim:
    In Copyright
    License Tesim:
    All rights reserved
    Resource Type:
    Article
    Identifier:
    10.1007/s40870-022-00359-2

  • 2. Mesoscale shock structure in particulate composites

    Description:
    Multiscale experiments in heterogeneous materials and the knowledge of their physics under shock compression are limited. This study examines the multiscale shock response of particulate composites comprised of soda-lime glass particles in a PMMA matrix using full-field high speed digital image correlation (DIC) for the first time. Normal plate impact experiments, and complementary numerical simulations, are conducted at stresses ranging from to elucidate the mesoscale mechanisms responsible for the distinct shock structure observed in particulate composites. The particle velocity from the macroscopic measurement at continuum scale shows a relatively smooth velocity profile, with shock thickness decreasing with an increase in shock stress, and the composite exhibits strain rate scaling as the second power of the shock stress. In contrast, the mesoscopic response was highly heterogeneous, which led to a rough shock front and the formation of a train of weak shocks traveling at different velocities. Additionally, the normal shock was seen to diffuse the momentum in the transverse direction, affecting the shock rise and the rounding-off observed at the continuum scale measurements. The numerical simulations indicate that the reflections at the interfaces, wave scattering, and interference of these reflected waves are the primary mechanisms for the observed rough shock fronts.
    Keyword:
    Shock structure, Shock compression, Composite, Plate impact, Digital image correlation, and Meso-scale
    Subject:
    Engineering and Applied Science
    Creator:
    Lawlor, Barry , Ravindran, Suraj , Gandhi, Vatsa , and Ravichandran, Guruswami
    Contributor:
    Jio Institute
    Owner:
    n.sakthivel@jioinstitute.edu.in
    Publisher:
    Elsevier
    Location:
    United States
    Language:
    English
    Date Uploaded:
    21-03-2023
    Date Modified:
    21-03-2023
    Date Created:
    01-02-2023
    Rights Statement Tesim:
    In Copyright
    License Tesim:
    All rights reserved
    Resource Type:
    Article
    Identifier:
    10.1016/j.jmps.2023.105239