Anisotropic nanomechanics of boron nitride nanotubes: Nanostructured “skin” effect

The stiffness and plasticity of boron nitride nanotubes are investigated using generalized tight-binding molecular dynamics and ab initio total energy methods. Due to boron nitride ~BN! bond rotation effect, compressed zigzag BN nanotubes are found to undergo anisotropic strain release followed by anisotropic plastic buckling. The strain is preferentially released toward N atoms in the rotated BN bonds. The tubes buckle anisotropically toward only one end when uniaxially compressed from both. A ''skin-effect'' model of smart nanocomposite materials is proposed, which localizes the structural damage toward the skin or surface side of the material.