Mechanics of boron nitride nanotubes: A continuum theory based on the interatomic potential

Boron nitride nanotubes (BNNTs) display unique properties and have many potential applications. An atomistic-based continuum theory is developed for BNNTs. The continuum constitutive model for BNNTs is obtained directly from the interatomic potential for boron and nitrogen. Such an approach involves no additional fitting parameters beyond those introduced in the interatomic potential. The atomistic-based continuum theory is then applied to study the Young's modulus, stress-strain curve and nonlinear bifurcation in BNNTs.;An analytic approach is then established to determine the tensile and bending rigidity of a hexagonal boron nitride (h-BN) monolayer and single- and multi-wall BNNTs directly from the interatomic potential. Such an approach enables one to bypass atomistic simulations and to give the tensile and bending rigidity in terms of the parameters in the potential. The thickness of h-BN monolayer is also discussed.;A hybrid atomistic/continuum model based on the interatomic potential for boron nitride is also developed to study the Stone-Wales transformation (90° rotation of an atomic bond) in boron nitride nanotubes under tension. It is found that the critical strains for Stone-Wales transformation for BNNTs agree well with the atomistic simulations.