TY - EJOU AU - Chiroiu, Veturia AU - Munteanu, Ligia AU - Delsanto, Pier Paolo TI - Evaluation of the Toupin-Mindlin Theory for Predicting the Size Effects in the Buckling of the Carbon Nanotubes T2 - Computers, Materials \& Continua PY - 2010 VL - 16 IS - 1 SN - 1546-2226 AB - Conventional continuum theories are unable to capture the observed indentation size effects, due to the lack of intrinsic length scales that represent the measures of nanostructure in the constitutive relations. In order to overcome this deficiency, the Toupin-Mindlin strain gradient theory of nanoindentation is formulated in this paper and the size dependence of the hardness with respect to the depth and the radius of the indenter for multiple walled carbon nanotubes is investigated. Results show a peculiar size influence on the hardness, which is explained via the shear resistance between the neighboring walls during the buckling of the multiwalled nanotubes. KW - Toupin-Mindlin strain gradient theory KW - nanoindentation KW - size effects KW - buckling KW - carbon nanotubes DO - 10.3970/cmc.2010.016.075