Chemistry Reference
In-Depth Information
9.5.1 BUCKLING BEHAVIOR OF CNTS
One of the technical applications on CNT related to buckling properties
is the ability of nanotubes to recover from elastic buckling, which allows
them to be used several times without damage. One of the most effec-
tive parameters on buckling behaviors of CNT on compression and tor-
sion is chirality that thoroughly investigated by many researchers [27, 28].
Chang et al. [29] showed that zigzag chirality is more stable than armchair
one with the same diameter under axial compression. Wang et al. [30]
reviewed buckling behavior of CNTs recently based on special character-
istics of buckling behavior of CNTs.
The MD simulations have been used widely for modeling buckling
behavior of CNTs [31-35]. MD use simulation package which included
Newtonian equations of motion based on Tersoff-Brenner potential of in-
ter atomic forces. Yakobson et al. [36] used MD simulations for buckling
of SWCNTs and showed that CNTs can provide extreme strain without
permanent deformation or atomic rearrangement. Molecular dynamics
simulation by destabilizing load that composed of axial compression, tor-
sion have been used to buckling and postbucking analysis of SWCNT [37].
The buckling properties and corresponding mode shapes were stud-
ied under different rotational and axial displacement rates which indicated
the strongly dependency of critical loads and buckling deformations to
these displacement rates. Also buckling responses of multiwalled carbon
nanotubes associated to torsion springs in electromechanical devices were
obtained by Jeong [38] using classical MD simulations.
Shell theories and molecular structural simulations have been used
by some researchers to study buckling behavior and CNT change ability
for compression and torsion. Silvestre et al. [39] showed the inability of
Donnell shell theory [40] and shown that the Sanders shell theory [41]
is accurate in reproducing buckling strains and mode shapes of axially
compressed CNTs with small aspect ratios. It's pointed out that the main
reason for the incorrectness of Donnell shell model is the inadequate kine-
matic hypotheses underlying it.
It is exhibited that using Donnell shell and uniform helix deflected
shape of CNT simultaneously, leads to incorrect value of the critical angle
of twist, conversely Sanders shell model with non uniform helix deflected
shape presents correct results of critical twist angle. Besides, Silvestre et
al. [42] presented an investigation on linear buckling and postbuckling
