TODAY, Tuesday 17-Jan-2023, 12:20pm Central
Prof. Suraj RavindranDepartment of Aerospace Engineering and Mechanics, University of Minnesota
Title: Mesoscale shock structure in particulate compositesAbstract: 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 the newly developed full-field
high-speed digital image correlation (DIC) for the first time. The high
spatial resolution measurement using high speed digital image
correlation allowed to measure the spatially resolved velocity profile.
Normal plate impact experiments, and complementary numerical
simulations, are conducted at stresses ranging from 1.1 − 3.1 GPa 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.For more information, visit the AEM Mechanics Research Seminar website:
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