4.8.3. Mechanical Properties of Nano-Tubes
The basic information needed for analysis are elastic modulus, stress-strain behavior,
strain capacity in compression and tension, shear modulus and strengths in various
modes. These values can be obtained using either experimental techniques or theoretical
formulations. The small dimensions of the tubes impose a tremendous challenge for
experimental study. Various types of high-resolution microscopes with the recent
innovative developments in the area of nano manipulation have helped to obtain
quantitative results. However, the numbers reported on strengths and modulus values
vary widely. The modulus values reported range from 270 to 3600 GPa. Theoretical
predictions indicate that the modulus can be as high as 5000 GPa. Typical stress-strain
plots reported two investigators are shown in Fig. 3 [10]. The stresses were estimated
assuming a uniform thickness of 0.34 nm for the single tube. The strains reported are
engineering strains.