Shockwave-induced plasticity via large-scale nonequilibrium molecular dynamics
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
Nonequilibrium molecular-dynamics (MD) simulations of shock waves in single crystals have shown that, above a threshold strength, strongly shocked crystals deform in a very simple way. Rather than experiencing massive deformation, a simple slippage occurs at the shock front, relieving the peak shear stress, and leaving behind a stacking fault. Later calculations quantified the apparent threshold strength, namely the yield strength of the perfect crystal. Subsequently, pulsed x-ray experiments on shocked single crystals showed relative shifts in diffraction peaks, confirming our MD observations of stacking faults produced by shockwave passage. With the advent of massively parallel computers, we have been able to simulate shock waves in 10-million atom crystals with cross-sectional dimensions of 100{times}100 fcc unit cells (compared to earlier 6{times}6 systems). We have seen that the increased cross-section allows the system to slip along all of the available {l_brace}111{r_brace} slip planes, in different places along the now non-planar shock front. These simulations conclusively eliminate the worry that the kind of slippage we have observed is somehow an artifact of transverse periodic boundary conditions. Thus, future simulations are much more likely to show that weak-shock plasticity is nucleated by pre-existing extended defects embedded in the sample. {copyright} {ital 1998 American Institute of Physics.}
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 302878
- Report Number(s):
- CONF-970707-; ISSN 0094-243X; TRN: 99:002530
- Journal Information:
- AIP Conference Proceedings, Vol. 429, Issue 1; Conference: Meeting of the topical group on shock compression of condensed matter of the American Physical Society, Amherst, MA (United States), 27 Jul - 1 Aug 1997; Other Information: PBD: Jul 1998
- Country of Publication:
- United States
- Language:
- English
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