Synopsis: Doubly Shocked

Shock waves in solids can propagate as a single structure made up of two zones with different mechanical properties.
Synopsis figure
Adapted from V. Zhakhovsky et al., Phys. Rev. Lett. (2011)

A shock wave is a pressure jump that propagates at supersonic speed. In solids, an impact or other sort of shock can generate two waves: an “elastic” compression wave followed by a separate, slower “plastic” wave that irreversibly deforms the material. At high impact intensity, the elastic wave was thought to disappear, resulting in a single plastic wave.  But in a paper in Physical Review Letters, Vasily Zhakhovsky of the University of South Florida, Tampa, and his colleagues now report simulations of high-pressure shock waves, in which a thin layer of elastic compression “paves the way” ahead of the advancing plastic wave front.

Prior models assumed that such a “two-zone” state should not exist, since any elastic zone would presumably be overridden by plastic deformations at the leading edge of a strong shock wave.  However, previous simulations were not able to follow the wave propagation in detail over long periods of time. The reported new molecular dynamics technique avoids this problem by simulating the shock wave inside a moving window. Material “flows” in from one edge of the window and out the other, as you would see if you filmed a wave while surfing on top of it. For a certain range of pressures, the authors identified an elastic compression zone that preceded the plastic deformation zone by a constant average distance that approaches a micron. The authors claim this could explain results of recent experiments studying shock waves in aluminum. – Michael Schirber


Features

More Features »

Announcements

More Announcements »

Subject Areas

Materials Science

Previous Synopsis

Particles and Fields

Slow Neutrons Are Dense

Read More »

Next Synopsis

Fluid Dynamics

Tiny Bubbles Burn Just Fine

Read More »

Related Articles

Synopsis: Tackling Electronic Correlations
Condensed Matter Physics

Synopsis: Tackling Electronic Correlations

A new “first principles” simulation method could broaden the range of strongly correlated materials whose properties can be theoretically predicted. Read More »

Viewpoint: Hydrogen Hides Surprises at High Pressure
Condensed Matter Physics

Viewpoint: Hydrogen Hides Surprises at High Pressure

Measurements of the melting curve of hydrogen at unprecedentedly high pressures call for a refinement of the theories describing the material. Read More »

Viewpoint: Porous Materials Exhibit Granular-Like Stress Chains
Materials Science

Viewpoint: Porous Materials Exhibit Granular-Like Stress Chains

Simulations of porous materials exhibit internal stress patterns like those in granular materials, despite the fact that these two systems are practically “negative images” of each other. Read More »

More Articles