In this paper, the effects of additives of a single-walled carbon nanotube (SWCNT) on the nonlinear free vibration of neat resin and carbon fiber reinforced polymer composites (CFRPs) are investigated experimentally. To establish this purpose a sensitive noncontact setup is designed and prepared. In order to obtain a proper SWCNT dispersion pattern, a simple multistage method is presented to fabricate and test nanocomposite beams. First, the increase in the Young's modulus of the nanocomposites by adding carbon nanotube is investigated using the mechanical bending test and validated with available test results. Next, the nonlinear free vibration behavior of cantilever beams under small to large-deflection is investigated. The results of the vibration tests indicate that the nonlinear vibration behavior of all models is close to homogenous materials with increasing SWCNT. The results also show that transverse initial excitation (displacement) imposed an axial load on the slender beams, which thus leads to an increase in the nonlinear frequency of oscillation. In addition, the increase in frequency bears a relation to the initial displacement. Also, large initial displacements, especially on models without carbon fiber (reinforced epoxy), cause that the convergence of frequencies under different initial excitation did not occur. The results of this study show that adding SWCNT can lead to convergences of frequencies’ hybrid composites and reinforced epoxy during final cycles.
The main goal of this research is to extract a suitable continuum modeling of buckyball-C60. For this purpose, firstly the lattice structure of buckyball-C60 is modelled and subsequently a spherical structure equivalent to fullerene structure is considered. The fullerene structure modeled with shell elements is under internal pressure and in the continuum shell modeling process. The results of simulation demonstrate that the fullerene structure can be modelled using spherical structure. The comparison between strain energies of the equivalent fullerene spherical model and molecular mechanics model under radial displacement, shows that C60fullerene spherical structures can be modeled using a shell with 0.665 Å thickness, 5.07 TPa elastic modulus and 0.165 Poisson's ratio or a shell with 0.75 Å thickness, 4.84 TPa elastic modulus and 0.19 Poisson's ratio. Moreover, the applied elliptical strain is used to demonstrate that the performance of the continuum spherical shell model of C60 is faultless.
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