Carbon Nanotube-reinforced Polymer Research Articles

Active vibration control of piezoelectric multilayers FG‐CNTRC and FG‐GPLRC plates

AbstractThis study investigates the active vibration control of multilayer Functionally Graded Carbon NanoTube Reinforced polymer Composite (FG‐CNTRC) plates and multilayer functionally graded graphene platelets reinforced polymer composite (FG‐GPLRC) plates covered with a piezoelectric layer (PZTG1195N) serve as both actuators and sensors. The plate's heart is supposed to be reinforced nonlinearly using both types of reinforcement. Active vibration control of plates under uniform load was achieved by utilizing a velocity feedback control algorithm with a specific gain value. The finite element method is employed to analyze both the static and dynamic behavior of a square plate discretized into 9‐node quadratic finite elements with 5 ° of freedom per node. The material properties are assumed to change across the thickness direction following a power law distribution, exhibiting various patterns: Uniform Distribution (UD), as well as Functionally Graded types X, O, and A (FG‐X, FG‐O, and FG‐A). The geometrical nonlinear equations are solved by the Newmark integration method. This work begins by validating the natural frequencies of a Functionally Graded (FG) composite plate reinforced with four different distributions of Nano‐filler and then aims to show the effect of the nonlinear distribution of nanofillers on the plate's stiffness. The Results obtained after the execution of a developed code highlight the significance of employing a nonlinear distribution of nanofillers to attenuate vibrations.Highlights FG composite and sandwich plates reinforced with GPLs and CNTs. Effect of nonlinear nanofillers distribution of reinforcement on free and forced vibration. The ability of the nonlinear distribution of nanofillers to attenuate forced vibrations.

Enhancing the performance of anti-blast windows through the use of carbon nanotube reinforced polymer gaskets

Anti-blast windows are critical in ensuring the safety of structures exposed to explosive threats, such as terrorist attacks or accidental explosions. These windows consist of blast-resistant glass and a structural framing system that must be able to withstand the high-pressure shock of an explosion. The present study presents a novel structural framing system for anti-explosion windows that adheres to the standards set forth by the American Institute of Steel Construction (AISC) 360-16 Specifications and the Aluminum Design Manual (ADM) 2020. The system encompasses a distinct combination of aluminum 6063-T6 angles and ASTM A36 steel embed plates that are connected by spaced bolts and augmented by the addition of a carbon nanotube-reinforced polymer CNT/polymer gasket. A numerical investigation utilizing ABAQUS software was performed to evaluate the mechanical behavior of the window assembly under intense blast loads, taking into account the effect of incorporating the CNT/polymer gasket and the impact of the gasket weight fraction on the performance of the structure. The results of the study demonstrate that the use of the CNT/polymer gasket and increasing the wight fraction ratio resulted in improvement of the blast performance of the window frame structure in terms of the significant reduction in stress, deformation and rotation, as well as the increasing of the energy dissipation during the blast event compared to when the gasket was not utilized. These findings offer crucial benchmarks for the proposed structure and offer recommendations for its implementation in industry practice, with the ultimate goal of developing more efficient and effective designs for anti-explosion windows that meet industry standards.

Percolation in Carbon Nanotube-Reinforced Polymers for Strain-Sensing Applications: Computational Investigation on Carbon Nanotube Distribution, Curvature, and Aggregation.

The present article investigates the possibility of simulating the electrical conductivity of carbon nanotube-reinforced polymer composites by numerical methods. Periodic representative volume elements are generated by randomly distributing perfectly conductive reinforcements in an insulating matrix and are used to assemble an electrical network representative of the nanocomposite, where the nanotube-nanotube contacts are considered equivalent resistors modeled by means of Simmons' equation. A comparison of the results with experimental data from the literature supports the conclusion that a random distribution of reinforcements is not suitable for simulating this class of materials since percolation thresholds and conductivity trends are different, with experimental percolation taking place before the expectations. Including nanotube curvature does not solve the issue, since it hinders percolation even further. In agreement with experimental observations, the investigation suggests that a suitable approach requires the inclusion of aggregation during the volume element generation to reduce the volume fraction required to reach percolation. Some solutions available in the literature to generate properly representative volume elements are thus listed. Concerning strain sensing, the results suggest that representative volume elements generated with random distributions overestimate the strain sensitivity of the actual composites.

Carbon nanotube-reinforced polymer nanocomposites for sustainable biomedical applications: A review

Carbon nanotube-reinforced polymer nanocomposites for sustainable biomedical applications: A review

Multi-Response Modelling and Optimization of Agave Cantala Natural Fiber and Multi-wall Carbon Nano Tube Reinforced Polymer Nanocomposite: Application of Mixture Design

Multi-Response Modelling and Optimization of Agave Cantala Natural Fiber and Multi-wall Carbon Nano Tube Reinforced Polymer Nanocomposite: Application of Mixture Design

Performance Evaluation and Sustainability Assessment in Laser Micro-drilling of Carbon Nanotube-Reinforced Polymer Matrix Composite Using MOORA and Whale Optimization Algorithm

Performance Evaluation and Sustainability Assessment in Laser Micro-drilling of Carbon Nanotube-Reinforced Polymer Matrix Composite Using MOORA and Whale Optimization Algorithm

An analytical solution for vibro-acoustic characteristics of sandwich panel with 3DGrF core and FG-CNT reinforced polymer composite face sheets

This paper presents the analytical solution on vibro-acoustic characteristics of three-dimensional graphene foam core and functionally graded carbon nanotube-reinforced polymer face sheet (3DGrFC-CNTRPFS) sandwich panel. Stress resultants of functionally graded carbon nanotube reinforced composite face sheets and 3D graphene foam core are determined by integrating their relevant stress expressions over the thickness of the face sheet and core, respectively. Further, this stress resultants are used in the equation based on Hamilton's principle to develop the governing equation. The third-order shear deformation theory is used to capture the effect of transverse shear in dynamic response. Based on mode superposition principle, the vibration response is calculated. This vibration response is given as an input to the Rayleigh integral to calculate the sound radiation characteristics. The study focuses on capturing the acoustic characteristics by varying the porosity coefficient of 3D graphene foam in the core while the carbon nanotubes are varied along with the thickness of the face sheets. The detailed analysis of the effect of the various functionally graded pattern of carbon nanotube and porosity coefficient of 3D graphene foam on acoustic characteristics is studied and the results are discussed.

Development of an advanced Takayanagi equation for the electrical conductivity of carbon nanotube-reinforced polymer nanocomposites

Currently available models for the conductivity of nanocomposites commonly disregard the roles of interphase and tunneling sections. Here, the interphase and tunneling parts are considered to yield an expanded Takayanagi equation to express a model for the electrical conductivity of carbon nanotubes (CNTs)-reinforced polymer nanocomposites (PCNTs). Invoking the interphase section, the operative filler loading and percolation onset are shown to control the volume fraction of networks. Application of the advanced model allows calculation of the conductivity over disparate ranges of various factors and estimation of the conductivity for real specimens. Experimental data for several examples show good matching with the predictions. Straighter CNTs, a dense interphase region, large nets, large tunneling diameter, low polymer tunneling resistivity, and short tunnels give rise to high conductivity. Conductivity is increased to 3.5 S/m at a CNT radius (R) of 5 nm and a CNT length of 20 μm, whereas an insulating sample is observed at R > 8 nm. A percolation onset (ϕp) below 0.0012 results in a conductivity of 0.13 S/m, but it decreases to 0.1 S/m at ϕp> 0.0044. A high CNT volume fraction of 0.02 raises the conductivity to 0.35 S/m, whereas a low CNT volume fraction of 0.005 lowers it to 0.05 S/m.

Fabrication, Functionalization, and Application of Carbon Nanotube-Reinforced Polymer Composite: An Overview.

A novel class of carbon nanotube (CNT)-based nanomaterials has been surging since 1991 due to their noticeable mechanical and electrical properties, as well as their good electron transport properties. This is evidence that the development of CNT-reinforced polymer composites could contribute in expanding many areas of use, from energy-related devices to structural components. As a promising material with a wide range of applications, their poor solubility in aqueous and organic solvents has hindered the utilizations of CNTs. The current state of research in CNTs—both single-wall carbon nanotubes (SWCNT) and multiwalled carbon nanotube (MWCNT)-reinforced polymer composites—was reviewed in the context of the presently employed covalent and non-covalent functionalization. As such, this overview intends to provide a critical assessment of a surging class of composite materials and unveil the successful development associated with CNT-incorporated polymer composites. The mechanisms related to the mechanical, thermal, and electrical performance of CNT-reinforced polymer composites is also discussed. It is vital to understand how the addition of CNTs in a polymer composite alters the microstructure at the micro- and nano-scale, as well as how these modifications influence overall structural behavior, not only in its as fabricated form but also its functionalization techniques. The technological superiority gained with CNT addition to polymer composites may be advantageous, but scientific values are here to be critically explored for reliable, sustainable, and structural reliability in different industrial needs.

Reliability evaluation of Carbon-Nanotube-Reinforced-Polymer composites based on multiscale finite element model

Experimental investigations to study the material behavior of nanocomposites have limitations. Hence, computational modeling and simulation encompassing multiscale material behavior provide an alternate approach to study the mechanical properties of such materials. The objective of the present work is to develop a computational framework for performing a probabilistic analysis of a Carbon-Nanotube-Reinforced-Polymer (CNRP) material by using the stress-strength model to determine the reliability and hazard associated with its mechanical properties, in terms of its longitudinal elastic modulus and ultimate longitudinal strength. A 3D multiscale finite element model of the Representative Volume Element of the nanocomposite consisting of a polymer matrix, an imperfect Single-Walled-Carbon-Nanotube (SWCN) and an imperfect interface region has been constructed for this purpose. The polymer matrix is modeled with the Mooney-Rivlin strain energy, the imperfect SWCN is modeled as a space frame structure using the Morse potential, and the interface region is modeled via van der Waals (vdW) links. In practical applications, the SWCN is not perfect, and it possesses structural defects, and moreover, the vdW links are not perfect. Such imperfections are characterized using the Monte Carlo simulation technique. The reliability and Hazard functions of the CNRP material are calculated using the Maximum Entropy Method.

Prediction of interface stiffness of single-walled carbon nanotube-reinforced polymer composites by shear-lag model

Interfacial stress transfer of single-walled carbon nanotube-reinforced polymer composites subjected to uniaxial tension was investigated by a newly developed shear-lag model integrated with a spring layer model. A linear relationship between the tangential relative displacement and the interfacial shear stress was assumed for the interface which is determined by van der Waals forces. The interface stiffness parameter was determined through comparing the stress distribution of the shear-lag model with multiscale simulation results. The effect of the interface stiffness and the nanotube’s aspect ratios on the distribution of stress in CNT-reinforced composites was studied.

Enhancement of stiffness and dynamic mechanical properties of polymers using single-walled-carbon-nanotube – a multiscale finite element formulation study

The static and dynamic mechanical properties of polymeric materials can greatly be enhanced by using carbon nanotubes as reinforcement material. However, studies still need to be carried out to characterize the dynamic mechanical properties of the Carbon-Nanotube-Reinforced-Polymer (CNRP) material. Experimental investigations for this purpose have severe limitations and, in most cases, appropriate and reliable experimental work could not be carried out. Computational modelling and simulation encompassing multiscale material behavior provides an alternate approach to study the material behavior. The objective of the present work is to study the enhancement of stiffness and dynamic mechanical properties of Carbon-Nanotube-Reinforced-Polymer (CNRP) material by using a 3D multiscale finite-element model of the representative volume element of the CNRP material. A composite material model consisting of a polymer matrix, an interface region, and a Single-Walled Carbon Nanotube (SWCNT) is constructed for this purpose. The polymer matrix is modeled with the Mooney-Rivlin strain energy function to calculate its non-linear response and the interface region is modeled via van der Waals links. The SWCNT is modeled as a space frame structure by using the Morse potential and as a thin shell model based on Donnell’s Shell Theory. The stiffness response of the CNRP is calculated and the natural frequencies of the CNRP are also determined. The viscoplastic behavior of the polymer matrix material is considered and the rate-dependent characteristics of the CNRP are studied. The damping properties of the CNRP are investigated based on its viscous and structural damping mechanisms. The effectiveness of the SWCNT reinforcement is quantified and characterized.

A new form of a Halpin–Tsai micromechanical model for characterizing the mechanical properties of carbon nanotube-reinforced polymer nanocomposites

In the present work, a new form of a Halpin–Tsai (H–T) micromechanical model is proposed to characterize the elastic modulus and tensile strength of carbon nanotube (CNT)-reinforced polymer nanocomposites. To this end, three critical factors, including random dispersion, non-straight shape and agglomerated state of the CNTs are appropriately incorporated into the H–T model. A comparison of the model predictions with some experiments on the CNT/polymer nanocomposites serves to verify the applicability of the proposed approach. It is found that the present predictions are in good agreement with the available experimental data. The results clearly reveal that for a more accurate prediction of the mechanical properties of the CNT/polymer nanocomposites, considering the random orientation, waviness and agglomeration of CNTs into the polymer matrix is critically essential. Also, some parametric studies are carried out to show the effects of volume fraction, non-straight shape, aspect ratio, mechanical characteristics and non-uniform dispersion of CNTs as well as matrix properties on the elastic modulus and tensile strength of CNT/polymer nanocomposites. The results reveal that it is necessary to eliminate the agglomeration and use the straight CNTs if the full potential of CNT reinforcement is to be realized.

Recent Advances in Characterization Techniques for the Interface in Carbon Nanotube-Reinforced Polymer Nanocomposites

The current state of characterization techniques for the interface in carbon nanotube-reinforced polymer nanocomposites is reviewed. Different types of interfaces that exist within the nanocomposites are summarized, and current efforts focused on understanding the interfacial properties and interactions are reviewed. The emerging trends in characterization techniques and methodologies for the interface are presented, and their strengths and limitations are summarized. The intrinsic mechanism of the interactions at the interface between the carbon nanotubes and the polymer matrix is discussed. Special attention is given to research efforts focused on chemical functionalization of carbon nanotubes. The benefits and disadvantages associated with covalent and noncovalent functionalization methods are evaluated, respectively. Various techniques used to characterize the properties of the interface are extensively reviewed. How the mechanical and thermal properties of the nanocomposites depend on the physical and chemical nature of the interface is also discussed. Better understanding and design of the interface at the atomic level could become the forefront of research in the polymer community. Potential problems going to be solved are finally highlighted.

Dynamic response of Carbon-Nanotube-Reinforced-Polymer materials based on multiscale finite element analysis

Nanocomposites are preferred over conventional materials because of their superior mechanical properties. Studies need to be carried out, especially on the dynamic response of the composite material. The objective of the present work is to study the dynamic response of Carbon-Nanotube-Reinforced-Polymer (CNRP) material by developing a 3D multiscale finite-element model of the Representative Volume Element (RVE) of the composite material to determine its dynamic properties, in terms of its natural frequencies and damping properties. A computational model consisting of a Single-Walled Carbon Nanotube (SWCN), an interface region and the polymer matrix is constructed for this purpose. The SWCN is modeled as a space frame structure by using the Morse potential and as a thin shell model based on Donnell's Shell Theory. The polymer matrix is modeled with the Mooney-Rivlin strain energy to calculate its non-linear response and the interface region is modeled via van der Waals links based on the Lennard-Jones Potential. The natural frequencies of CNRP are compared with the natural frequencies of the polymer matrix. A relation between damping ratio and natural frequencies is then obtained. Finally, the analysis of harmonic response is conducted to characterize the effects of the SWCN reinforcement in the polymer material.

Effects of curvature and alignment of carbon nanotubes on the electrical conductivity of carbon nanotube-reinforced polymers investigated by mesoscopic simulations

Carbon nanotube-reinforced polymers belong to a class of composite materials, which have been largely investigated due to their special electrical, thermal and mechanical properties. In the case of electrical conductivity of carbon nanotube-reinforced polymer, a critical amount of carbon nanotubes as a filler material enables a sharp increase of electrical conductivity. At this certain volume fraction of carbon nanotubes, the material turns into a conductor because of the percolation effect. This effect occurs due to the formation of a closed pathway of filler material through the system. Mesoscopic simulation models of these materials were carried out to predict their electrical conductivity. In this paper, the effects of carbon nanotube curvature and their alignment parallel or perpendicular to the electrical flow direction inside a representative volume element were analysed and an optimized carbon nanotube distribution is presented. A network with a longest average path length per (rigid) carbon nanotube but also cross-linking (only nearly isotropic alignment) shows the best conductivity in the preferred direction.

Large deformation bending responses of nanotube-reinforced polymer composite panel structure: Numerical and experimental analyses

The large deformation deflection responses of randomly oriented multi-walled carbon nanotube-reinforced polymer composite structures were examined theoretically using a novel higher order shear deformation kinematic model. Moreover, the excess geometrical distortion within the structure is incorporated via the full geometrically nonlinear strain–deformation relations (Green–Lagrange strain) including all of the nonlinear higher order terms to achieve the generality. The randomly oriented nanotube-reinforced polymer composite properties were evaluated computationally via Mori–Tanaka scheme for the theoretical analysis purpose. The deflection responses were evaluated numerically using an original MATLAB program with the help of the direct iterative method and finite element steps. The performance of the currently developed numerical model was verified by solving various numerical examples for the convergence and subsequent comparison purpose. Also, the deflection values were evaluated experimentally and compared with the current numerical results using the experimentally obtained elastic properties. Finally, the generality and the applicability of the currently developed higher order nonlinear finite element model is revealed by solving various numerical examples.

Carbon nanotube-reinforced smart composites for sensing freezing temperature and deicing by self-heating

Carbon nanotube-reinforced polymer composites were fabricated by high shear mixing. The microstructure and the electrical properties of the carbon nanotube–polymer composites were investigated by scanning electron microscopy and electrical resistance measurement. We found that the carbon nanotube composites showed high electrical conductivity (1.5 S m−1) at 7.0 wt% of carbon nanotubes, and the increase in thickness enhanced the electrical conductivity of the composites. The multifunctional properties of the carbon nanotube composites were also investigated for use in sensing the freezing temperature and also in deicing by self-heating. The results showed that the carbon nanotube–polymer composites had high temperature sensitivity in the freezing temperature range from −5 to 5 C and an excellent heating performance due to the Joule heating effect. The carbon nanotube composites are promising to be used as smart coating materials for deicing by self-heating as well as by detection of the freezing temperature.

Nonlinear finite element solutions of thermoelastic flexural strength and stress values of temperature dependent graded CNT-reinforced sandwich shallow shell structure

This research article reported the nonlinear finite solutions of the nonlinear flexural strength and stress behaviour of nano sandwich graded structural shell panel under the combined thermomechanical loading. The nanotube sandwich structural model is derived mathematically using the higher-order displacement polynomial including the full geometrical nonlinear strain-displacement equations via Green-Lagrange relations. The face sheets of the sandwich panel are assumed to be carbon nanotube-reinforced polymer composite with temperature dependent material properties. Additionally, the numerical model included different types of nanotube distribution patterns for the sandwich face sheets for the sake of variable strength. The required equilibrium equation of the graded carbon nanotube sandwich structural panel is derived by minimizing the total potential energy expression. The energy expression is further solved to obtain the deflection values (linear and nonlinear) via the direct iterative method in conjunction with finite element steps. A computer code is prepared (MATLAB environment) based on the current higher-order nonlinear model for the numerical analysis purpose. The stability of the numerical solution and the validity are verified by comparing the published deflection and stress values. Finally, the nonlinear model is utilized to explore the deflection and the stresses of the nanotube-reinforced (volume fraction and distribution patterns of carbon nanotube) sandwich structure (different core to face thickness ratios) for the variable type of structural parameter (thickness ratio, aspect ratio, geometrical configurations, constraints at the edges and curvature ratio) and unlike temperature loading.

Theoretical and experimental investigation of vibration characteristic of carbon nanotube reinforced polymer composite structure

The vibration frequencies of multi-walled carbon nanotube-reinforced polymer composite structure are examined numerically via a generic higher-order shear deformation kinematics for different panel geometries. The extensive behaviour of the current higher-order model is demonstrated by comparing the results with the published data including the own in-house experimental values. In this analysis, the required elastic properties of the randomly distributed nanotube-reinforced polymer composite panel are evaluated numerically using Mori–Tanaka scheme. Firstly, the equation of motion of the vibrated nanotube composite panel derived via the classical Hamilton's principle and the isoparametric finite element steps are implemented for the numerical purpose. Further, the modal responses are obtained computationally using an original computer code (MATLAB) with the help of the higher-order finite element formulation. The necessary convergence and subsequent comparison have been made for the presently developed numerical model with those available published results including the values obtained via commercial package (ANSYS). Additionally, the model validation has been established by comparing the present numerical frequency values with the lab-scale free vibration experimental data. The specific conclusions are drawn by examining different numerical examples for various structural parameters using the experimental properties.