Simulating materials failure by using up to one billion atoms and the world's fastest computer: Work-hardening

Abstract

We describe the second of two large-scale atomic simulation projects on materials failure performed on the 12-teraflop ASCI (Accelerated Strategic Computing Initiative) White computer at the Lawrence Livermore National Laboratory. This investigation simulates ductile failure by using more than one billion atoms where the true complexity of the creation and interaction of hundreds of dislocations are revealed.

Figure 1

Early-time sequence of the propagating dislocations is shown growing as partial landscapes and the subsequent collision of the dislocations from the opposing notches. The reduced times in a clockwise sequence are 0, 22.5, 45 and 67.5 (reduced time units). Only atoms with a potential energy less than 97% of the bulk value are displayed, resulting in the selected visualization of atoms neighboring surfaces and dislocations.

Figure 2

Close-up snapshots of the propagating dislocations and rigid junctions evolving into a complex topology of the defect-solid landscape. The time interval in the dynamics is 290 to 430 (reduced time units).

Figure 3

Late-time snapshot picture of the dislocation network of the billion atom slab. A coarse grain cubical skeleton of rigid junctions (sessile dislocations) becomes apparent from a distant view. The reduced time is 700.

Figure 4

Magnified view of the rigid junction network at a reduced time of 900.

Figure 5

The total number of atoms associated with dislocations of all types is plotted versus time (in units of 100 time steps equal to 0.045 reduced time units).