Molecular dynamics simulation of timescale effect and lattice transformation of copper nanorod under bending

Abstract

Mechanical behaviors of materials and structures at nanoscale are essentially different from those at macroscale, resulting from surface effect, size effect and time scale effect. In some experimental research at nanoscale, the bending displacement of nanorod is measured and used to gain the lateral force. In our present work, the bending behavior of metal Cu nanorod is simulated by molecular dynamics method. Embedded-atom potential is employed to represent the atomic interactions. The simulation results show that the bending behavior of metal nanorod is significantly loading rate dependent and nonlinear. It is found that in the elastic bending process, crystal lattice can transform from FCC structure to HCP structure. After such lattice transformation, metal nanorod is thickened and shortened. Its bending stiffness is remarkably strengthened. Whether lattice transformation occurs or not depends on both the loading magnitude and the loading rate.