• Advances in nano research
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• v.9 no.3
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• pp.193-210
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• 2020

In this research, beside presenting real images of produced Functionally Graded Carbon Nanotube-Reinforced Composites (FG-CNTRCs) and a brief review of the synthesis method of FG-CNTRCs, static and buckling analysis of FG-CNTRC with piezoelectric layers are investigated. It is assumed that the material properties of FG-CNTRC are varied through the thickness direction using four different distributions of Carbon Nanotubes (CNTs). To capture the size effects, nonlocal elasticity theory proposed by A.C. Eringen is also adopted in our model. One of the topics in our paper is using a higher order theory with eight different displacement fields and comparing their results with each other. To solve the governing equations, an analytical method is used to find the deflections and critical buckling loads of FG-CNTRCs. To show the accuracy of present methodology, our results are compared with the results of simply supported rectangular nano plates available in the literature. In this research, the effects of aspect ratio, piezoelectric layer and nonlocal parameter are also studied. It is hoped that this work leads to more accurate models on FG-CNTRC.

• Steel and Composite Structures
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• v.24 no.6
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• pp.727-740
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• 2017

The present paper studies the stability analysis of the continuously graded CNT-Reinforced Composite (CNTRC) panel stiffened by rings and stringers. The Stiffened Panel (SP) subjected to axial and lateral loads is reinforced by agglomerated CNTs smoothly graded through the thickness. A two-parameter Eshelby-Mori-Tanaka (EMT) model is adopted to derive the effective material moduli of the CNTRC. The stability equations of the CNRTC SP are obtained by means of the adjacent equilibrium criterion. Notwithstanding most available literature in which the stiffener effects were smeared out over the respective stiffener spacing, in the present work, the stiffeners are modeled as Euler-Bernoulli beams. The Generalized Differential Quadrature Method (GDQM) is employed to discretize the stability equations. A numerical study is performed to investigate the influences of different types of parameters involved on the critical buckling of the SP reinforced by agglomerated CNTs. The results achieved reveal that continuously distributing of CNTs adjacent to the inner and outer panel's surface results in improving the stiffness of the SP and, as a consequence, inclining the critical buckling load. Furthermore, it has been concluded that the decline rate of buckling load intensity factor owing to the increase of the panel angle is significantly more sensible for the smaller values of panel angle.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1465-1471
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• 2013

The electrical and mechanical properties of room temperature vulcanized (RTV) silicone rubber composites are investigated as functions of multi-walled carbon nanotube (CNT), carbon black (CB), and thinner content. The thinner is used to improve the CNT and CB dispersion in the matrix. The electrical and mechanical properties of the composite with CNT are improved when compared to the composite with CB at the same content. As the thinner content is 80 phr, the electric resistance of the composite decreases significantly with the CNT content and shows contact point saturation of CNT at 2.5 phr. As the thinner content increases, the dispersion of conductive particles improves; however, the critical CB content increases because of the reduction in the CB weight ratio. It is believed that an electrode that needs good flexibility and excellent electrical properties can be manufactured when the amount of CNT and CB are increased with the thinner content.

• Computers and Concrete
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• v.20 no.2
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• pp.229-246
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• 2017

The dynamic bending response of single walled carbon nanotube reinforced composite (SWCNTRC) plates subjected to hygro-thermo-mechanical loading are investigated in this paper. The mechanical load is considered as wind pressure for dynamic bending responses of SWCNTRC plate. The dynamic version of the High Order shear deformation Theory (HSDT) for a composite plate with Matrix and SWCNTRC plate is first formulated. Distribution of fibers through the thickness of the SWCNTRC plate could be uniform or functionally graded (FG). The dynamic displacement response is predicted by using Nemarck integration method. The effective material properties of SWCNTRC are estimated by using micromechanics based modeling approach. The effect of different environmental condition, volume fraction of SWCNT, Width-to-thickness ratio, wind pressure, different SWCNTRC-FG plates, boundary condition, E1/E2 ratio, different temperature on dynamic displacement response is investigated. The dynamic displacement response is compared with the available literature and it shows good agreement.

• Transactions of Materials Processing
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• v.19 no.7
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• pp.423-428
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• 2010

Carbon nanotubes(CNTs) are expected to be ideal reinforcements of metal matrix composite materials used in aircraft and sports industries due to their high strength and low density. In this study, a high pressure torsion(HPT) process at an elevated temperature(473K) was employed to achieve both powder consolidation and grain refinement of aluminummatrix nanocomposites reinforced by 5vol% CNTs. CNT/Al nanocomposite powders were fabricated using a novel molecular-level mixing process to enhance the interface bonding between the CNTs and metal matrix before the HPT process. The HPT processed disks were composed of mostly equilibrium grain boundaries. The CNT-reinforced ultrafine grained microstructural features resulted in high strength and good ductility.

• Structural Engineering and Mechanics
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• v.76 no.1
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• pp.27-56
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• 2020

In this paper, the deflection and buckling analyses of porous nano-composite piezoelectric plate reinforced by carbon nanotube (CNT) are studied. The equations of equilibrium using energy method are derived from principle of minimum total potential energy. In the research, the non-local strain gradient theory is employed to consider size dependent effect for porous nanocomposite piezoelectric plate. The effects of material length scale parameter, Eringen's nonlocal parameter, porosity coefficient and aspect ratio on the deflection and critical buckling load are investigated. The results indicate that the effect of porosity coefficient on the increase of the deflection and critical buckling load is greatly higher than the other parameters effect, and size effect including nonlocal parameter and the material length scale parameter have a lower effect on the deflection increase with respect to the porosity coefficient, respectively and vice versa for critical buckling load. Porous nanocomposites are used in various engineering fields such as aerospace, medical industries and water refinery.

• Steel and Composite Structures
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• v.29 no.3
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• pp.319-332
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• 2018

This paper investigates the free vibration of geometrically imperfect functionally graded car-bon nanotube-reinforced composite (FG-CNTRC) beams that are integrated with two sur-face-bonded piezoelectric layers and subjected to a combined action of a uniform temperature rise, a constant actuator voltage and an in-plane force. The material properties of FG-CNTRCs are assumed to be temperature-dependent and vary continuously across the thick-ness. A generic imperfection function is employed to simulate various possible imperfections with different shapes and locations in the beam. The governing equations that account for the influence of initial geometric imperfection are derived based on the first-order shear deformation theory. The postbuckling configurations of FG-CNTRC hybrid beams are determined by the differential quadrature method combined with the modified Newton-Raphson technique, after which the fundamental frequencies of hybrid beams in the postbuckled state are obtained by a standard eigenvalue algorithm. The effects of CNT distribution pattern and volume fraction, geometric imperfection, thermo-electro-mechanical load, as well as boundary condition are examined in detail through parametric studies. The results show that the fundamental frequency of an imperfect beam is higher than that of its perfect counterpart. The influence of geometric imperfection tends to be much more pronounced around the critical buckling temperature.

• Composites Research
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• v.29 no.4
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• pp.161-166
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• 2016

Carbon nanotube buckypaper (CNTs-BP)/thermoplastic polyurethane (PU) elastomer composites were successfully fabricated. The CNTs-BP/PU nanocomposites exhibited simultaneous improvements in both tensile modulus and strength by 1360 and 430%, respectively, as compared to pure PU. Possible reinforcing mechanisms were evidenced by SEM analyses and tensile tests. The CNTs-BP/PU nanocomposites can be potentially used as an inter-reinforcing agent in ultra-lightweight, high-strength aircraft, carbon-fiber-reinforced plastics, etc.

• Polymer(Korea)
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• v.35 no.1
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• pp.60-65
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• 2011

In order to maximize the performance of polymer nano-composites, it is essential to understand an effect of a dispersion state on material properties as well as to achieve highly dispersed composites. In this work, a simple quantitative approach to evaluate the degree of dispersion was suggested for carbon nanotube (CNT) embedded polymer nano-composites. Through UV-visible spectroscopy analysis, the transmittance of nano-composites was measured at various dispersion states and it was found that the transmittance reduced as the dispersion state of CNT improved. Based on the results, an effective concentration factor for quantitative evaluation of dispersion state was introduced into the Beer-Lambert transmittance law. The proposed method and parameter to evaluate the degree of dispersion were verified by analyzing the transmittances at different dispersion states of CNT, concentrations of CNT and sample thicknesses.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.164-165
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• 2006

Carbon nanotube(CNT)-reinforced poly(ethylene-co-ethyl acrylate)(EEA) nanocomposites were prepared by melt mixing with a Haake internal mixer. The CNT loading was vaned from 0 to 20 wt%. The changes m CNT dispersion and shape were investigated with FE-SEM observation with and without the Tensile strain of 40%. The CNT was protruded over the fracture surface upon Tensile strain, which is a very interesting behavior.