Mechanical behavior of a carbon nanotube turf
by Harish Radhakrishnan, M.S.
Washington State University
Chair: Sinisa Dj. Mesarovic
Carbon nanotubes grown on a substrate form a turf – a complex structure of
intertwined, mostly nominally vertical tubes, cross-linked by adhesive contact and a few
bracing tubes. The mechanical behavior of such a turf is analyzed and the physical
mechanism of deformation deduced on the basis of (a) experimental results – standard
and continuous stiffness nanoindentation tests and (b) micromechanical scaling analysis.
The objective here is to develop a phenomenological model to simulate the behavior of
the turf in nanoindentation tests, taking into account the various features observed during
Under moderate strains and deformations, the turf is fully reversible (non-linear
elastic response) with a small Kelvin-Voigt type relaxation. Also observed in the
experiments is the strong adhesion between the turf and indenter tip – due to the van der
Waals forces of attraction. A finite element model has been developed and is able to
reproduce the results from the indentation tests with reasonable accuracy.
While the adhesive contact in the indentation of linear elastic solids is thought to
be well understood through analytical models, a finite element model for the problem is
yet to be developed. To benchmark the developed contact algorithm, runs were done to
compare the results with existing theories of adhesion. The comparison revealed an
unanticipated deviation from the existing models and is thought to be due to the finite
deformation in the elastic material, not considered by the existing theories.
School:Washington State University
School Location:USA - Washington
Source Type:Master's Thesis
Keywords:nanotubes carbon and graphite products
Date of Publication: