Deformation behaviors of an armchair boron-nitride nanotube under axial tensile strains

Abstract

Deformation behaviors of an (8,8) boron-nitride nanotube (BNNT) under axial tensile strains were investigated via molecular dynamics (MD) simulations. The Tersoff potential was employed in the simulations with potential parameters determined by fitting the MD simulations results to those obtained from density functional theory calculations for BNNTs with the aid of the force-matching method. Variations in the axial stress, bond lengths, bond angles, radial buckling, and slip vectors with tensile strain were all examined. The axial, the radial, and tangential components of the slip vector were employed to monitor the local elongation, the local necking, and the local twisting deformations, respectively, near the tensile failure of the BNNT. From this study, it was noted that the BNNT started to fail at the failure strain of 26.7%. The components of the slip vector grew abruptly and rapidly after the failure strain, especially for the axial component. This implies that the local elongation dominates the tensile failure of the BNNT. With further axial tensile strains, subsequent bond breaking was found in the BNNT and finally resulted in a chain-like failure mode before complete breaking of the BNNT. No apparent yielding was noticed before the tensile failure of the BNNT.