Tensile strength of single-walled carbon nanotubes with defects under hydrostatic pressure

Elastic properties and tensile strength of single-walled carbon nanotubes, which have topological and coordinated defects, under hydrostatic pressure have been studied by using molecular-dynamics simulations and ab initio electronic structure calculations. The Young's moduli in both the axial direction and the radial direction are determined under different levels of hydrostatic pressure. It is found that the stiffness of the nanotubes changes with the strain in a graded manner. When the strain is larger than 0.10, the tubes become softened. The strength at failure of the tubes is lowered by the existence of the defects.