PNNL

Abstract

Molecular dynamics methods using the Tersoff bond-order potential are performed to study the nanomechanical behavior of [111]-oriented ß-SiC nanowires under tension, compression, torsion, combined tension-torsion and combined compression-torsion. Under axial tensile strain, the bonds of the nanowires are just stretched before the failure of nanowires by bond breakage. The failure behavior is found to depend on size and temperatures. Under axial compressive strain, the collapse of the SiC nanowires by yielding or column buckling mode depends on the length and diameters of the nanowires, and the latter is consistent with the analysis of equivalent continuum structures using Euler buckling theory. The nanowires collapse through a phase transformation from crystal to amorphous structure in several atomic layers under torsion strain. Under combined loading the failure and buckling modes are not affected by the torsion with a small torsion rate, but the critical stress decreases with increasing the torsion rate. Torsion buckling occurs before the failure and buckling with a big torsion rate. Plastic deformation appears in the buckling zone with further increasing the combined loading.