Atomistic study of the mechanical response of copper nanowires under torsion

The length, loading rate and thermal effects on the torsional response of hollow copper nanowires are investigated with molecular dynamics simulation. Evolution of atomic configuration is studied, which shows that partial dislocations nucleated from the surfaces accommodate the plastic deformation of the nanowires under torsion. With the increase in torsional angle, necking appears and the corresponding cross-section transforms from a hollow square to a solid circle. Meanwhile, atomic rearrangement from being amorphous to fcc occurs, which becomes more obvious at higher loading rates. To understand the relation between material and geometrical instabilities, the torsional buckling mode is also investigated and found to strongly depend on both wire length and temperature.