Fig. 5. Defect orientation, shape, and scale.

(A) Effect of chirality on the defect orientation and length 2a. The direction of the load is indicated by the solid arrow. (B) Vacancy defects of equivalent SWNT strength, sharing the same length 2a and tip curvature r₀, but with different width 2b, shape, and orientation. The dashed arrows indicate possible crack propagation paths. (C) Comparison of defects at the microscale and nanoscale. Microscale defects are surrounded by a continuum and, if sharp, can cause infinite stress concentrations. Nanoscale defects (that is, SWNT vacancies) are surrounded by a truss-like lattice (they are not sharp), cause finite stress concentrations, and cannot be smaller than a minimal size 2a_min (the length of a monovacancy).