Effect Of Carbon Nanotubes Agglomeration Research Articles

Vibration and buckling analysis of agglomerated CNT composite plates via isogeometric analysis using non-polynomial shear deformation theory

The present study employs the non-polynomial shear deformation theory within the framework of isogeometric analysis to study the vibration and buckling behavior of carbon nanotubes reinforced composite plates. Owing to the higher aspect ratio of carbon nanotubes, they are prone to agglomeration in matrix. Therefore, to analyze the effect of carbon nanotubes agglomeration in composite plates, a two-parameter micromechanics model is used to determine the effective mechanical properties of the composite plate. Current study opts isogeometric analysis as numerical method, as it can represents the complex shape geometries, and provides higher-order element continuity. Higher-order element continuity is desirable for implementation of non-polynomial shear deformation theory. By the virtue of non-uniform rational B-splines, isogeometric analysis turns out to be better analysis numerical method for complex and shell structures. Governing isogeometric element equations are derived using Hamilton's principle. A detailed parametric study is also performed to investigate the effect of degree of agglomeration, thickness to length/radius ratio, different boundary conditions, and complex shape cutouts in a composite plate. The presented formulation is validated across analytical and finite element method solutions with available literature.

Thermal free vibration examination of sandwich piezoelectric agglomerated randomly oriented CNTRC Timoshenko beams regarding pyroelectricity

For the first time, thermal free vibration examination of sandwich piezoelectric agglomerated Timoshenko beams strengthened by carbon nanotubes is addressed here considering the pyroelectric effect. The top, and the bottom layers are piezoelectric layers serve as a sensor. The host lamina is a polymer matrix strengthened by means of randomly oriented carbon nanotubes. Mori-Tanaka's approach is used to define the thermal and mechanical attributes of the carbon nanotube reinforced nanocomposite. The effect of carbon nanotube agglomeration is incorporated to the constitutive relations. The behavior of the materials is considered to be linearly elastic. The Chebyshev-Ritz method is used to derive the correlated natural frequencies. The influences of the pyroelectricity and the carbon nanotube agglomeration on the first natural frequency are investigated for three different boundary conditions. The results show that the first natural frequency decreases by neglecting the effect of the pyroelectricity. In addition, the agglomeration eliminates the possibility of static instability predicted for the nanocomposite beam exposed to a thermal ambient.

Buckling behavior of porous CNT-reinforced plates integrated between active piezoelectric layers

This work presents the buckling resistance of a novel active multidisciplinary sandwich plate (AMSP) under in-plane mechanical load or temperature change. The proposed sandwich plate includes an advanced porous core reinforced with carbon nanotubes (CNTs) integrated between two active piezoelectric faces. Functional graded (FG) profiles are considered for the dispersions of CNTs and porosity along the thickness of core layer. In addition, the effect of CNT agglomeration in core layer on the buckling resistance of the proposed AMSP has been studied by employing Eshelby-Mori-Tanaka (EMT)'s approach. A third order shear deformation theory (TSDT) of plates is adopted to obtain governing Eigen value equations for the thermal and mechanical buckling analyses of AMSP. The critical buckling resistance of each analysis has been extracted from the governing equations through a developed mesh-free solution based on moving least squares (MLSs) shape functions. The impacts of porosity, CNTs and geometrical dimensions on the buckling resistance of AMSPs have been investigated. The results show that embedding porosity in core results in a slight reduction in mechanical responses and a significant improvement in thermal buckling resistance. Moreover, reinforcing core layer with CNTs leads to remarkable drop and increase in thermal and mechanical buckling resistances, respectively. However, the formation of CNT agglomerations significantly reduces such CNTs impacts.

Vibrational analysis of sandwich sectorial plates with functionally graded sheets reinforced by aggregated carbon nanotube

In the present work, by considering the agglomeration effect of single-walled carbon nanotubes, free vibration characteristics of functionally graded nanocomposite sandwich sectorial plates are presented. The volume fractions of randomly oriented agglomerated single-walled carbon nanotubes are assumed to be graded in the thickness direction. To determine the effect of carbon nanotube agglomeration on the elastic properties of carbon nanotube-reinforced composites, a two-parameter micromechanical model of agglomeration is employed. In this research work, an equivalent continuum model based on the Eshelby–Mori–Tanaka approach is considered to estimate the effective constitutive law of the elastic isotropic medium (matrix) with oriented straight carbon nanotubes. The two-dimensional generalized differential quadrature method as an efficient and accurate numerical tool is used to discretize the equations of motion and to implement the various boundary conditions. The proposed sectorial plates are simply supported at radial edges, while all possible combinations of free, simply supported, and clamped boundary conditions are applied to the other two circular edges. The benefit of using the considered power-law distribution is to illustrate and present useful results arising from symmetric and asymmetric profiles. The effects of agglomeration, geometrical, and material parameters together with the boundary conditions on the frequency parameters of the sandwich functionally graded nanocomposite plates are investigated. It is shown that the natural frequencies of structure are seriously affected by the influence of carbon nanotubes agglomeration. This study serves as a benchmark for assessing the validity of numerical methods or two-dimensional theories used to analyze the sandwich sectorial plates.

The effect of carbon nanotubes agglomeration on vibrational response of thick functionally graded sandwich plates

In the present work, by considering the agglomeration effect of single-walled carbon nanotubes, free vibration characteristics of functionally graded (FG) nanocomposite sandwich plates resting on Pasternak foundation are presented. The volume fractions of randomly oriented agglomerated single-walled carbon nanotubes (SWCNTs) are assumed to be graded in the thickness direction. To determine the effect of CNT agglomeration on the elastic properties of CNT-reinforced composites, a two-parameter micromechanical model of agglomeration is employed. In this research work, an equivalent continuum model based on the Eshelby-Mori-Tanaka approach is employed to estimate the effective constitutive law of the elastic isotropic medium (matrix) with oriented straight CNTs. The 2-D generalized differential quadrature method (GDQM) as an efficient and accurate numerical tool is used to discretize the equations of motion and to implement the various boundary conditions. The proposed rectangular plates have two opposite edges simply supported, while all possible combinations of free, simply supported and clamped boundary conditions are applied to the other two edges. The benefit of using the considered power-law distribution is to illustrate and present useful results arising from symmetric and asymmetric profiles. The effects of twoparameter elastic foundation modulus, geometrical and material parameters together with the boundary conditions on the frequency parameters of the laminated FG nanocomposite plates are investigated. It is shown that the natural frequencies of structure are seriously affected by the influence of CNTs agglomeration. This study serves as a benchmark for assessing the validity of numerical methods or two-dimensional theories used to analysis of laminated plates.

The effect of carbon nanotube agglomeration on the thermal and mechanical properties of polyethylene oxide

AbstractThe effects of agglomerated versus deagglomerated multiwalled carbon nanotubes on the thermal and mechanical characteristics of polyethylene oxide were studied. The specimens were prepared via solution‐sonication method, using two procedures. In the first procedure, CNT‐PEO solutions were prepared with as‐received MWCNTs, before sonication using an ultrasonic bath; in the second procedure, aggregated MWCNTs were first deagglomerated using high‐intensity ultrasonic processor, before mixing with the PEO. The two solution preparation procedures did result in significant thermal property differences such as increased transition temperature and crystallinity, but only one mechanical property can be conclusively associated with the sample preparation method—the breaking strain which was marginally higher for nanocomposites containing deagglomerated CNTs, although in all cases the breaking strains were much lower for nanocomposites than for unfilled polymer. However, the overall results confirm the effectiveness of CNTs both as nucleation agents for semicrystalline polymers, and as fillers for enhancement of mechanical properties of the matrix polymer. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers