Cracking the Sound Barrier

New simulations show it is possible for shear-induced cracks to travel at transsonic and supersonic speeds under certain conditions, contradicting classical theory. These simulations were performed in the fall of 2000 on several thousand processors of the initial-delivery ASCI White supercomputer at Lawrence Livermore National Laboratory. This is the work of Farid Abraham of IBM Almaden Research, in collaboration with LLNL personel Mark Duchaineau, Tomas Diaz De La Rubia, Brian Wirth, Terry Heidelberg, Mark Seager, and others.


HARM versus ANHARM: MPEG -- QUICKTIME -- QUICKTIME (no credits)

This movie compares the propagation speeds in the harmonic and anharmonic materials, and includes credits.

HARM: MPEG -- QUICKTIME

This movie shows the crack propagation in the harmonic (linear) material. The speed in this case is transsonic after the emergence of the daughter crack. A very large image (one atom per pixel) is available for frame 700 in TIFF format.

ANHARM: MPEG -- QUICKTIME

This movie shows the crack propagation in the anharmonic (stiff) material. The speed in this case is supersonic after the emergence of the daughter crack. A very large image (one atom per pixel) is available for frame 700 in TIFF format.

MIXED: MPEG -- QUICKTIME

This movie shows the crack propagation in a bilayer material with the top half of the slab being harmonic, and bottom half being anharmonic. The speed in this case shows a hybrid behaciour, where the crack first goes transsonic after the emergence of the daughter crack, and later on goes supersonic after the emergence of a granddaughter crack. A very large image (one atom per pixel) is available for frame 700 in TIFF format.


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