Modeling and Simulating Dislocation Dynamics Near Sound Speeds in Cubic Crystals
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
The motion of crystal dislocations near sound speeds is investigated using atomic-scale molecular dynamics (MD) simulations and continuum equations of motion. A material’s deformation rate is influenced by whether dislocations can propagate in the high-velocity high-stress regime. In the femto-second resolved MD simulations, a shear stress is applied to a pair of partial edge dislocations in copper at T = 25 K, and the pair’s average position is tracked with time. Analysis for the steady-state motion reveals that the dislocations can move faster than at least two transverse sound speeds depending on the applied stress. On the modeling side, the dislocation glide equations govern the evolution of the local displacement field according to material elastic constants. A second-order accurate finite difference scheme is applied to solve the screw dislocation equation in the continuum limit for aluminum. This method proved difficult to implement due to numerical instabilities surrounding the dislocation core, so alternative solving schemes may be needed. Combining an external acceleration with the equation of motion should reveal whether the strain energy density remains finite at transonic and supersonic glide speeds.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- DOE Contract Number:
- 89233218CNA000001
- OSTI ID:
- 1545735
- Report Number(s):
- LA-UR-19-26824-Rev.1
- Country of Publication:
- United States
- Language:
- English
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