Nanotube Volume Fraction Research Articles

Mobility of Polymer Melts in a Regular Array of Carbon Nanotubes

In polymer nanocomposites, mechanical properties essentially depend on the alignment of nanoparticles and polymers. In this work, we investigate an entangled polymer melt in a confinement computationally, in order to get an insight into the mobility behavior of the polymer chains. The confinement consists of nanotubes, arranged in a hexagonal array. We use dissipative particle dynamics, a fast, soft-core simulation method, and reintroduce entanglement dynamics via slip-springs. We observe a distinct influence of the confinement as diffusion is increased in the direction parallel to the nanotubes. Furthermore, we observe that an orientation of the polymers parallel to the nanotubes and chains are compressed in the direction orthogonal to their primitive path. The diffusion parallel to the nanotubes increases further as we increase the nanotube volume fraction in our systems. Moreover, we investigate the slip-spring distribution in the proximity of the nanotube surfaces of our fast and simple slip-spring model, which we find to coincide with results reported for more sophisticated and expensive methods. Our DPD model shows potential applicability to a wide range of polymer nanocomposites while preserving reptation behavior, which is typically lost due to the use of soft-core models.

An effect of MHD fluid flow heat transfer using CNTs with thermal radiation and heat source/sink across a stretching/shrinking sheet

Current work studies the magnetohydrodynamics (MHD) flow of the boundary layer and heat transfer with carbon nanotubes. Furthermore, the velocity and temperature profiles are examined using different physical parameters. The governing equations are reduced to highly nonlinear partial differential equation and ordinary differential equation via similarity variables that can be solved analytically. This research focuses on the magnetohydrodynamics flow and heat transfer of carbon nanotubes across a flat plate. Water is utilised as a base fluid with two types of carbon nanotubes; SWCNT (single wall carbon nanotubes) and MWCNT (multi wall carbon nanotubes). Carbon nanotubes have a wide range of industrial, biomedical, energy production, and space cooling applications because they can improve the thermal properties of base materials. The present work of the magnetohydrodynamics fluid flow with mass transpiration using carbon nanotubes due to a stretching/shrinking surface is deliberated in the momentum and temperature profiles. Moreover, when compared to the lower branch solutions, the upper branch solutions of the magnetic field profiles are analytically stable. According to the results, in comparison to negative values, positive values of the magnetohydrodynamics flow give stable profiles. The new research is expected to serve as a foundation for the dual solution of different sorts of Newtonian fluid flows across diverse types of surfaces. The impact of the actual boundaries used in the issue is discovered, and the results are graphically shown and analyzed. The momentum and temperature profiles of water-SWCNTs are significantly higher than those of water-MWCNTs, while fluid movement slows in the nanofluid region due to nanoparticle temperature and the thickness of the thermal boundary layer increases as the volume fraction of carbon nanotubes increases.

Nonlinear free vibrations and stability analysis of FG-CNTRC pipes conveying fluid based on Timoshenko model

The nonlinear free vibrations and stability of pipes conveying fluid constructed of Functionally Graded Carbon Nano-Tube Reinforced Composite (FG-CNTRC) materials are studied in this paper. The material properties of FG-CNTRC are supposed to be graded within the thickness direction and estimated by the modified rule of mixtures. The equations of motion of the system are derived using the extended Hamilton’s principle for open systems based on Timoshenko beam theory. To consider nonlinear effects, large deformations-small strains hypothesis is adopted by applying the von Kármán geometric nonlinear theory. The nonlinear free vibration and the fluid flow effects in the pipe system are investigated numerically, employing the super convergent finite element method to discretize nonlinear coupled partial differential equations. This is a powerful method to accurately predict steady state response of a dynamical system. The Newmark and Newton-Raphson methods are also applied to solve the resulted set of ordinary nonlinear differential equations. The applicability of the proposed mathematical approach is then be studied through several numerical investigations with different parameters including nanotube volume fraction, mass ratio, CNT distributions, fluid velocity and pipe geometry.

Bioconvective electromagnetohydrodynamic hybrid nanoliquid flow over a stretching sheet with stratification effects: a four-factor response surface optimized model

The current work presents a theoretical investigation on the bioconvective electromagnetohydrodynamic (EMHD) hybrid nanofluid flow over a stretching surface considering viscous dissipation, chemical reaction, and stratification effects. The highly nonlinear system of partial differential equations (PDEs) is reduced to a system of ordinary differential equations (ODEs) with the aid of effectual similarity transformations. The transmuted ODEs are then treated numerically using bvp4c (a finite difference-based built-in numerical procedure) in MATLAB. It is observed that an increase in the electric field parameter augments the velocity profile. It is also noted that the Nusselt number is a decreasing function of the thermal stratification parameter. Further, the influence of nanoparticle volume fraction of carbon nanotubes , the nanoparticle volume fraction of magnetite nanoparticles , Hartmann number , and electric field parameter on the drag coefficient has been statistically scrutinized utilizing the four-factor response surface methodology. The highest drag coefficient is experienced for smaller values of Hartmann number and larger values of electric field parameter. The current work finds application in cancer therapy, bio-microsystems, biomedical imaging, and therapeutic drug delivery.

Three-Dimensional Study of Magnetohydrodynamic Natural Convection, Entropy Generation, and Electromagnetic Variables in a Nanofluid Filled Enclosure Equipped with Inclined Fins.

This article provides a numerical study on carbon nanotube–water nanofluid convection in a three-dimensional cavity under a magnetic field effect. Two walls are kept at a hot temperature, and the upper and lower horizontal walls are considered adiabatic. As a new configuration, the beneficial effect of using a nanofluid is coupled with the incorporation of cold V-shape obstacle placed in the cubic cavity; in addition, an external magnetic field is applied toward the horizontal x-axis direction. The finite element method based on the Galerkin’s Weighted Residual technique is used to solve the three-dimensional governing equations. In this paper, the ranges of the parameters used are the Hartmann number, varied from 0 to 100, Rayleigh number from 103 to 105, nanofluid volume fraction between 0% and 4.5%, and the body V-shaped opening angle varied from 0 to 80°. The effect of the obstacle shape and the added nanoparticle concentration on the flow behaviors, the different instabilities generated, and the heat transfer exchanged were exposed. An enhancement in heat transfer was recorded by increasing the obstacle opening angle and the volume fraction of the carbon nanotubes. Special attention has also been devoted to the calculation of the different kinds of entropy generations.

Nonlinear Static Stability of Stiffened Nanocomposite Plate s Subjected Various Types of Loads

This work deals with the nonlinear buckling and post-buckling of stiffened nanocomposite plates reinforced functionally graded carbon nanotubes (FG CNTRC) resting on elastic foundation in thermal environment. Obtained results showed that the properties of the nanocomposited plates embedded with single-walled carbon nanotubes are dependent on temperature and altered according to linear functions of the thickness. The governing equations are derived by the third-order shear deformation plate theory taking into account von Kármàn geometrical nonlinearity and solved by both the Airy’s stress function and Galerkin method. In numerical results, the influences of various types of distribution and volume fractions of carbon nanotubes, geometrical parameters, elastic foundations on the nonlinear buckling and post-buckling behaviour of stiffened FG-CNTC plates subjected mechanical, thermal loading and both are demonstrated.
 Keywords: Stiffened FG CNTRC plates; Buckling and Post buckling analysis; Third-order shear deformation theory; Thermal environment; Galerkin method
 This work deals with the nonlinear buckling and post-buckling of stiffened nanocomposite plates reinforced functionally graded carbon nanotubes (FG CNTRC) resting on elastic foundation in thermal environment. Obtained results showed that the properties of the nanocomposited plates embedded with single-walled carbon nanotubes are dependent on temperature and altered according to linear functions of the thickness. The governing equations are derived by the third-order shear deformation plate theory taking into account von Kármàn geometrical nonlinearity and solved by both the Airy’s stress function and Galerkin method. In numerical results, the influences of various types of distribution and volume fractions of carbon nanotubes, geometrical parameters, elastic foundations on the nonlinear buckling and post-buckling behaviour of stiffened FG-CNTC plates subjected mechanical, thermal loading and both are demonstrated.

Modeling analysis of elastic properties of graphene‐carbon nanotube (G‐C) reinforced composites

AbstractThis article describes in detail the research on the elastic properties of carbon nanotube reinforced composite materials and graphene‐carbon nanotube (G‐C) reinforced composite materials. Several different composite material models were established using finite element software ABAQUS to study the influence of the inclination angle, quantity and volume fraction of carbon nanotubes and graphene on the elastic modulus of reinforced composites. The results show that as the volume fraction of graphene and carbon nanotubes increases, the Young's modulus and shear modulus of the reinforced composite material increase significantly. In addition, the tilt angle and quantity of graphene and carbon nanotubes will also affect the elastic properties of the composite material. The Young's modulus E and the shear modulus G decrease with the increase of the inclination angle, and increase with the increase of the number of graphene and carbon nanotubes.

Influence of Temperature and Moisture on Free Vibration Behavior of Skew Laminated Composite Sandwich Panels with CNTRC Core

This paper presents the influence of temperature and moisture on the free vibration characteristics of skew laminated composite sandwich (SLCS) panels. The face sheets of the panels are made of graphite–epoxy composite, while the core consists of carbon nanotube-reinforced composite. The coupled hygro-elastic and thermo-elastic relations for the SLCS shells/panels are formulated using first-order shear deformation theory. The nonmechanical stiffness matrices are represented by the initial stress stiffness matrix developed using nonlinear strain–displacement relations. The temperature and moisture-dependent material properties are considered to analyze the laminated composite sandwich spherical, hyperbolic, ellipsoid, cylindrical Shells, and flat plates. Several numerical examples are comprehensively studied to establish the influence of temperature, moisture, the volume fraction of carbon nanotubes in the core material, functional gradation types, skew angle, and edge constraints on the vibration responses of SLCS shells. Further exploration is devoted to studying the combined effect of moisture, temperature, and the geometrical parameters such as length to width ratio, length to thickness ratio, radius-to-length ratio, and the core thickness to face sheet thickness ratios on the natural frequency of the skew laminated composite sandwich panels.

Free vibrational analysis of composite beams reinforced with randomly aligned and oriented carbon nanotubes, resting on an elastic foundation

The main interest of this paperwork is to examinate the dynamic behavior (free vibrational response) of carbon nanotubes (CNT) composite beams standing on an elastic foundation of Winkler-Pasternak’s. The affected beam consists of a polymer matrix reinforced with single-wall carbon nanotubes (SWCNT’s), in which, a large number of CNT’s reinforcement of infinite length are distributed in a linear elastic polymer matrix. In this study the CNT’s are considered either aligned or randomly oriented on the matrix.
 A refined high-order beam theory (RBT) is adopted in the present analysis using a new shape function. The refined beam theory which is summarized by differentiating the displacement along the beam transverse section into shear and bending components, initially the material properties of the composite beam (CNTRC) are estimated using the Mori-Tanaka’s method. The beam is considered simply supported on the edge-lines. NAVIER’s solutions are proposed to solve the boundary conditions problems. Since there are no results to compare with in the literature; the results in this study are compared with a free vibrational analysis of an isotropic beam. Several aspects such as the length/thickness ratio, volume fraction of nanotubes, and vibrational modes are carried out in the parametric study.

Electromagnetic Flow of SWCNT/MWCNT Suspensions in Two Immiscible Water- and Engine-Oil-Based Newtonian Fluids through Porous Media

This article deals with steady-state laminar, electrically conducting immiscible fluids. The Newtonian fluid considered passes between two parallel vertical plates in a porous medium. The channel consists of two regions, one of them filled with engine-oil-based carbon nanotubes (CNTs) and the second region filled with water through a porous medium. The assumptions for the channel walls are electrically non-conducting and are at two different temperatures. Mathematical formulation is formed using rules for the conservation of mass, momentum and energy in both regions. Continuous conditions are used for velocity, temperature and also for shear pressure at the crossing area. The governing equations are first transformed in a non-dimensional form by using appropriate transformations, and then the subsequent differential equations are solved using a topological approach by means of the homotopy analysis method. It is found that the impact of the actual boundaries utilized in the issue is directed, and the outcomes are introduced graphically and discussed. It is noted that the engine-oil SWCNTs experience a significant increase in temperature profiles as compared to the engine-oil MWCNTs, while the movement of fluid slowdown in the nanofluid region due to the concentration of nanoparticles and the thickness of the thermal boundary layer increases by increasing the volume fraction of the carbon nanotubes.

Entropy generation and heat transfer analysis of magnetic nanofluid flow inside a square cavity filled with carbon nanotubes

Combination of MWCNTsandwater based nanofluid flow, isentropic lines and isotherms features inside a square enclosure with radiation and magnetic field is examined numerically in the current article. The dimensionless equations representing entropy generation, heat and momentum are solved numerically by applying finite difference scheme. The changes in the sketches of isotherms, streamlines and isentropic fields with dissimilar values of radiation parameter (0.01≤R≤0.1), volume fraction of nanoparticle parameter (0.01≤ϕ≤0.1), Rayleigh number (103≤Ra≤104), Prandtl number (5.2≤Pr≤8.2) and magnetic parameter (0.1≤M≤0.7) have scrutinized and are plotted through sketches. The scatterings of rates of heat transfer with respect to these parameters are also depicted through graphs. Non – dimensional rates of heat transfer intensifies in the nanofluid region with augmenting values of radiation parameter. The sketches of temperature lines of water−−MWCNTs based nanofluid lost their nature in the central part of the chamber and they are virtually vertical shape close to the right cold wall as the values of volume fraction of carbon nanotubes rises. 7.2% augmentation in heat transfer rate is noticed when 4% volume fraction of MWCNTs are added to the base fluid .

Research on anti-irradiation properties of PDMS/MWCNT composite force-sensitive structure

This study aimed to design a polydimethylsiloxane multi-walled carbon nanotube composite force-sensitive structure. Five composite materials with different volume fractions of carbon nanotubes were prepared, and the microscopic morphology of the samples recorded. Conductive pathways were formed inside the composite materials. The force-sensitive performance was verified through tensile experiments on the material. The sample with a content of 3 vol. % had a sensitivity of up to 165, which was good for detecting small strains. The samples were irradiated with 60Co-γ rays, and the irradiation doses were 5, 10, 20, 50, and 100 kGy. After irradiation with the highest dose of 100 kGy, the sensitivity of the sample with a content of 3 vol. % was reduced to 125. The samples exposed to different irradiation doses were stretched and released 3000 times to verify the repeatability of the force sensitive characteristics; almost no difference was found in the resistance strain results of the sample. Experiments showed that the designed composite force-sensitive structure had high sensitivity, good repeatability, and good resistance to gamma radiation.

Enhancement on flexural strength of glass fiber composite addition of nano clay and (Mwcnt) using novel C shaped spiral tube position by vacuum bag molding process

This study is to enhance and evaluate the Flexural strength of glass fiber reinforced polymer epoxy composite compared with the GFRP Epoxy composite with Nano clay filler. Epoxy resin (LY556) and hardener (HY951) were used as matrix materials and glass fiber as reinforcing material, montmorillonite Nanoclay of volume fraction 4 % as a filler. In the Control group Glass fiber Epoxy composite is taken as the control group (N = 20). Glass fiber with 4 % Nano clay filler reinforced epoxy composite is taken as an experimental group (N = 20) fabricated by the C shaped spiral tube position Vacuum bag process. The results obtained for 20 samples of plain and filler added GFRP composite specimens were recorded and analyzed using SPSS statistical analysis tool. The Glass fiber with 4 % volume fraction of NC filler and multiwall carbon nanotube reinforced epoxy composite compared with the Glass Fiber epoxy reinforced composite without filler shows the mean significant differences of p = 0.036 obtained using SPSS-V26 software. within the limits of this study the flexural strength of GFRP composite with 4 % volume fraction of Nano clay shows significantly higher flexural strength than the GFRP without filler composite.

Percolation Threshold and Depression in Properties of Polymer Nanocomposites

Percolation threshold is an important phenomenon to be addressed when producing nanocomposites, especially because the literature suggests a depression of properties near this region. In this study, epoxy matrix nanocomposites were produced with different volume fractions of multi-walled carbon nanotubes and were characterized according to their electrical, thermal, and mechanical properties. In addition, digital image correlation (DIC) was used to measure the strain of nanocomposites and to show how it behaves in different percolation states. Electrical conductivity indicated a percolation threshold near 0.22% v/v of nanoparticles. Differential scanning calorimetry analysis showed a depression followed by an increase in glass transition temperature near the percolation threshold. Tensile strength tests presented a depression followed by an increasing near percolation threshold. DIC images showed that nanocomposites present a different behavior when near the percolation threshold, with a more distributed strain over the surface of the sample under stress and fracture toughness decreased near the percolation threshold.

Static bending of functionally graded single-walled carbon nanotube conjunction with modified couple stress theory

This paper focused on studying the transeverse deflection behavior of three functionally graded microbeam models: material, porous material, and functionally graded single-walled carbon nanotube-reinforced composite (FG-SWCNTRC) microb beam. To calculate micro size effects of the non-classical beam model, the modified couple stress theory (MCST) uses just length material scale parameters. A numerical solution to the static deflection equation is the Lagrange multiplier method. The characteristics studied included length, material parameter ratio, volume fraction of material, porosity and carbon nanotube, SWCNT distribution types, boundary conditions, and aspect ratio (length/thickness). The static behavior of FG-micro beams demonstrates that the theory of modified couple stress (MCST) produces more accurate results than classical beams. This is especially true if the beam thickness is close to the length scale parameter. As the CNT volume fraction grows and the porosity volume fraction falls, the microbeam FG structure deflects less.

Effect of CNT volume fractions on nonlinear vibrations of PMMA/CNT composite plates: A multiscale simulation

The volume fraction of the carbon nanotube (CNT) plays a key role in ensuring the performance of the CNT reinforced polymer composite, especially under the severe vibration, which leads to the resonance and failure of the composite structure. In this paper, a bottom-up multiscale method is adopted to study the effect of the CNT volume fractions on the nonlinear vibration of the poly (methyl methacrylate) (PMMA)/CNT composite. According to the molecular simulation, the longitudinal, transverse and shear moduli of the PMMA/CNT nanocomposites are found to increase with the increasing CNT volume fractions. Substituting the simulated moduli into the extended rule of mixtures (EROM), the efficiency parameters of the PMMA/CNT composite with various CNT volume fractions are derived based on a homogenization approach. The derived efficiency parameters are used in the functionally graded (FG)-based EROM to obtain the expressions of the longitudinal, transverse and shear moduli of the macroscopic composite plate, so as to obtain the constitutive equation for the nonlinear vibrations of the FG-based PMMA/CNT composite plate. The subsequent meshless simulation results demonstrate that the natural frequencies of the FG-based composite plate increase with the increasing volume fractions, whereas the ratios of the nonlinear to linear frequencies decrease. Using the bottom-up multiscale analysis, the macroscopic vibration responses are analyzed for the PMMA/CNT composites with the CNT volume fractions up to 9.0%, which provides a paradigm of the design of the PMMA/CNT composite by considering the CNT volume fraction effect.

Modeling thermo‐mechanical behaviors of carbon nanotube/polyurethane functionally graded shape memory polymer beam

AbstractIn this paper, a new constitutive model which can model the thermo‐mechanical behaviors of functionally graded shape memory polymer (SMP) beam is established. The kinematic equation was established based on the SMP constitutive equation further derived and Euler–Bernoulli beam theory. The material parameter equations were established by taking the volume fraction of carbon nanotubes (CNT) as the gradient based on the material parameter equations of SMP and properties of functionally graded materials. According to the constitutive model, the simply supported beam was taken for example to be solved and simulated by using the virtual work principle. The results show material parameters properties, deflection properties, stress properties and shape memory properties of CNT/carbon nanotube/polyurethane (PU) functionally graded beam and some conclusions are concluded. This work shows the thermo‐mechanical behavior of CNT/PU functionally graded beam, and it provides a theoretical basis for the practical application of functionally graded SMP materials.

Effect of carbon nanotube-reinforced magneto-electro-elastic facings on the pyrocoupled nonlinear deflection of viscoelastic sandwich skew plates in thermal environment

This work presents a finite-element-based numerical formulation to evaluate the nonlinear deflections of magneto-electro-elastic sandwich skew plates with a viscoelastic core and functionally graded carbon nanotube-reinforced magneto-electro-elastic face sheets. Meanwhile, the proposed formulation accommodates the geometrical skewness as well. The magneto-electro-elastic sandwich skew plate is operated in the thermal environment and subjected to various multiphysics loads, including electric and magnetic loads. The viscoelastic core is modelled via the complex modulus approach. Two different forms of viscoelastic cores, such as Dyad 606 and EC 2216, are considered in this study. Also, different thickness configurations of core and facing arrangements are taken into account. The plate kinematics is presumed through higher-order shear deformation theory, and von Karman's nonlinear strain displacement relations are incorporated. The global equations of motion are arrived at through the total potential energy principle and solved via the direct iterative method. Special attention is paid to assessing the influence of pyroeffects, coupling fields and electromagnetic boundary conditions on the nonlinear deflections of magneto-electro-elastic sandwich plates working in the thermal environment and subjected to electromagnetic loads, which is the first of its kind. Also, parametric studies dealing with the skew angles, carbon nanotube distributions and volume fractions, thickness ratio, and aspect ratio have been discussed. The results of this work are believed to be unique and serve as a guide for the design engineers towards developing sophisticated smart structures for various engineering applications.

An effect of MHD and radiation on CNTS-Water based nanofluids due to a stretching sheet in a Newtonian fluid

The present article makes on the presence of the magnetohydrodynamic (MHD) flow of an electrically conducting Newtonian fluid over a superlinear stretching/shrinking sheet. A similarity transformation is utilized to interpret the representing construction of nonlinear PDEs by nonlinear ODEs. These equations are solved analytically along with the corresponding boundary conditions. The impact of radiation, mass transpiration, and carbon nanotube (CNT) volume fraction on MHD Newtonian fluid flow and heat transfer is under investigation. Water, ethylene glycol, and engine oil are used as base liquids in the sample along with single and multi-walled carbon nanotubes (MCNTs). Heat transfer in an electrically conducting fluid, including internal heat generation and absorption, is evaluated over a continuously stretching/shrinking sheet with power-law surface temperature or heat flux. Furthermore, the heat equation is solved analytically via the Kummer’s function and WKB method, respectively. The studied results verify that CNTs have significant properties in improving heat transfer processes which have been extensively developed in manufacturing industrial applications, especially in nanomedicine, where the use of carbon nanotubes as drug-carriers is being pursued, particularly in cancer treatment.

A thermal conductivity model for hybrid heat and mass transfer investigation of single and multi-wall carbon nano-tubes flow induced by a spinning body

The enhancement of thermal heat transfer utilizing the hybrid nanofluids is explored widely by numerous researchers over the years. Because of these exciting characteristics features of hybrid nanofluids, the prime focus of this article is the investigation of engine oil and mineral oil-based hybrid nanofluids consisting of carbon nanotubes (SWCNT-MWCNT) over a rotating cone present in a convectively heated permeable environment. In the flow supposition, a mathematical model is formulated, Boundary layer approximations are used to minimize the structure of partial differential equations. The dimensionless system of highly non-linear partial differential equations is obtained through boundary layer approximation. The findings obtained showed a rise in temperature for both CNT's, the thickness of the thermal boundary layer has increased under the impact of solid volume fraction of nanotubes. SWCNTs provide a reduction in skin friction and enhancement in Nusselt number. The hybrid nanofluid with EO (engine oil) base has demonstrated a greater heat transfer coefficient and reduced fluid motion's skin friction than MO (mineral oil) based. The model hybrid flow can be used in industries like turbine heat production, wind energy generation, and pharmaceutical processes.