کلیدواژهها
عنوان مقاله English
نویسندگان English
For extraordinary properties of carbon nanotube (CNT), a lot of research has been done about its
application to reinforce different materials such as electronic and building materials, and good effects
of CNT have been observed. Experimental approach for determining the properties of composites
containing fibers, especially carbon nanotubes, needs using of complex experimental methods and
expensive laboratorial equipments. Theoretical approach can lower the cost of predicting properties of
these composites. So, in this paper, an analytical relation is presented by continuum mechanics method
to predict the compressive strength of cement composite reinforced with carbon nanotube. For
simplicity of computations, carbon nanotubes were assumed to be isotropicand firstly oriented
unidirectionally and uniformly in the cement composite. Representative Elementary Volume(REV), as
anindicatorelement of this nanocompositeis, was chosen and analyzed by continuum mechanics
method. A fiber embedded in a cylinder of cement with certain radius is named REV. The strains
under loads were calculated and the stresses were obtained by Hook’s law. Then, for prediction failure
of composite, von Mises’ yield criterion was applied and by that, the compressive strength of cement
composite reinforced with unidirectionally oriented carbon nanotubes was obtained. For real cases, the
results of this analysis should be generalized to cement composites reinforced with random orientation
of nanotubes, since there is no control on the distribution of fibers in the laboratory and they are
oriented randomly in composites, although researchers are studying on production of CNT/cement
composites with arbitrary orientation of fibers.To apply the random orientation effect, Cox’s method
was used. For this purpose, the fibers' distribution function f ( ) was assumed and it was observed
that the random orientation of fibers reduces the effect of fiber reinforcing with respect to
unidirectional orientation. Therefore, an orientation factor 1 was used considering random
orientation in comparison with unidirectional orientation. As a suggestion, this factor can be
experimentally obtained too. Experimental method was used to determine the orientation factor of
fibers incomposites and good results were obtained. Then the presented analytical relationship was
compared with experimental data. Matches and differences between the analytical method and the
experimental data were studied and the suggestions were presented to lower the differences between
the analytical and experimental methods. The effect of some parameters such as compressive strength
of cement and the amount of carbon nanotubes added on the compressive strength of CNT/cement
composite were obtained too. Accordingly that an ideal nanocomposite with regard to economical
considerations can be obtained.
کلیدواژهها English
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