Plasticity induced by shock waves in nonequilibrium molecular-dynamics simulations

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Understanding material behavior under extreme conditions like shock waves is crucial for designing robust materials.
• Previous simulations were limited in scale, potentially introducing artifacts and limiting the observation of complex phenomena.

Purpose of the Study:

• To investigate the behavior of shock waves in large-scale three-dimensional face-centered cubic crystals.
• To explore the influence of initial material inhomogeneities on shock wave response.
• To elucidate the nanostructure formed after shock wave propagation.

Main Methods:

• Utilized nonequilibrium molecular-dynamics simulations with 10-million atoms.
• Simulated shock waves in 3D face-centered cubic crystals with large cross-sectional dimensions.
• Introduced non-flat piston faces to mimic material inhomogeneities.

Main Results:

• Observed widespread slip along all available 111 slip planes in the large-scale simulations.
• Confirmed that slippage is not an artifact of periodic boundary conditions by comparing with smaller simulations.
• Demonstrated that stacking faults can be nucleated by pre-existing defects for shock waves below the perfect-crystal yield strength.

Conclusions:

• Shock waves in large FCC crystals induce complex slip patterns and rich nanostructures.
• Material inhomogeneities play a critical role in defect nucleation under weaker shock conditions.
• The study provides insights into the fundamental mechanisms governing material response to dynamic loading.