Volume Fraction Of Carbon Nanotubes Research Articles

Effect of carbon nanotubes on mechanical properties of aluminum matrix composites: A review

Abstract Carbon nanotubes (CNTs) are renowned for their low density, high elastic modulus, and exceptional electrical and thermal properties. The continuously developing applications of CNTs provide higher specific stiffness and strength for composite materials. The unique characteristics of CNTs make them ideal reinforcing particles in aluminum matrix composites (AMMCs), which generally exhibit excellent mechanical properties. CNTs/AMMCs are usually prepared using methods such as powder metallurgy, casting, spray deposition, and reactive melting. The uniform diffusion of CNTs in composites is crucial for enhancing the properties of CNTs/AMMCs. The properties of CNTs/AMMCs largely depend on the content, morphology, and distribution of reinforcements in the matrix and the interaction between reinforcements and the matrix. By adding an appropriate volume fraction of CNTs, the hardness, tensile strength, compressive strength, and electrical properties of CNTs/AMMCs were significantly improved. The effects of CNT content on the mechanical properties of CNTs/AMMCs, including the tensile strength, yield strength, compressive strength, stress–strain curve behavior, elastic modulus, hardness, creep, and fatigue behavior, were revealed. The design of microstructure, optimization of the preparation process, and optimization of composition can further improve the mechanical properties of CNTs/AMMCs and expand their application in engineering. The design concept of integrating material homogenization and functional unit structure through biomimetic design of novel gradient structures, layered structures, and multi-level twin structures further optimizes the composition and microstructure of CNTs/AMMCs, which is the key to further obtaining high-performance CNTs/AMMCs. As a multifunctional composite material, CNTs/AMMCs have broad application prospects in fields such as air force, military, aerospace, automation, and electronics. Moreover, CNTs/AMMCs have potential applications in cell therapy, tissue engineering, and other areas.

Characterization and Evaluation of Mechanical Properties of Carbon Nanotube Filler Epoxy Composite

The outstanding mechanical properties of carbon nanotubes (CNT) have made them the focus of extensive investigation. To characterize and study the effects of the different volume fraction of multi walled carbon nanotubes (MWCNTs) on the mechanical properties of the nanocomposites attempted. The purpose of this work is to use experimental techniques to ascertain the mechanical characteristics of the nanocomposite. Tests on mechanical tensile strength were conducted to see how the MWCNT filler content affected the reinforced epoxy nanocomposite. The result of altered percentage of MWCNTs on the mechanical properties of the composites had been inspected. Results showed that 0.2 wt% MWCNT addition has the best effect on the mechanical properties of the matrix.

Magnetohydrodynamic flow of carbon nanotubes and heat transfer over a moving thin Needle: A numerical and research surface methodology

A steady flow of carbon nanotubes (CNTs) nanofluids and heat transfer past a horizontally moving thin needle are investigated under the influence of magnetohydrodynamic (MHD). Single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) are the two main nanoparticles that represent CNTs. The slender needle moves relative to the flow with parallel velocity in either the same or opposite direction. Using the similarity method, a system of partial differential equations (PDEs) subject to boundary conditions is converted into nondimensional ordinary equations (ODEs). The ODEs are then reduced to a first-order ODEs system and solved using the MATLAB R2022b bvp4c solver. On a numerical scale, the impacts of varying potential parameters, such as the magnetic, CNTs’ volume fraction, and moving parameters, on the velocity and temperature profiles, the skin friction, and heat transfer coefficients are investigated. Utilising response surface methodology (RSM), the optimisation of the response based on numerical experimentation of physical quantities is performed. The outcomes are depicted using tables and a graphical approach. Results indicate the existence of dual solutions when the needle travels in the opposite direction. Moreover, the increase in the magnetic parameter by 100% in the flow will increase both the skin friction and heat transfer coefficients by nearly 30% and 4%, respectively. Furthermore, when the value of the CNTs volume fraction increases by 100%, the heat transfer rate increases substantially by almost 33%.However, doubling the size of the thin needle cansignificantly reduce the skin friction coefficient by nearly 32%. RSM results demonstrate that the maximal heat transfer coefficient is generated at the highest values of the magnetic and CNTs’ volume friction parameters and the lowest value of the needle size parameter. Findings also show that SWCTNs are superior to MWCNTs both in the skin friction and heat transfer coefficients. When comparing the performance of water and kerosene, we find that water is less effective as a base fluid than kerosene.

Strain-rate sensitivity analysis of microwave processed polypropylene-carbon nanotube composites

The study investigates the strain rate sensitivity of microwave-processed polypropylene nanocomposites containing a 10% volume fraction of multi-walled carbon nanotubes (MWCNTs), synthesized using a domestic microwave applicator (DMA). Through experimental analysis under various loading conditions including tensile, flexural, and multistep relaxation loads, the mechanical strength of these nanocomposites is assessed alongside destructive testing and scanning electron microscopy (SEM) results. Mathematical models are proposed to elucidate the mechanical response under different strain rate loadings. The nanocomposite exhibits elastoplastic behavior, with maximum elongation observed at a strain rate of 3 mm/min. During uniaxial tension tests, the ultimate strength increases significantly from 5.74 MPa at 1.52 mm/min to 13.8 MPa and 15.7 MPa at 1 mm/min and 2 mm/min respectively during multistep relaxation tests. The true stress-true strain curve follows a power law of strain hardening under high strain rate tensile tests. Flexural tests reveal maximum flexural strength and modulus at a strain rate of 1.25 mm/min, with elongation peaking at 1.50 mm/min. Mechanical properties, including modulus and ultimate strength, show an increasing trend with strain rate until a limiting value is reached, beyond which thermal softening occurs. SEM fractography illustrates the random and spatial distribution of CNTs at low strain rates, whereas agglomeration and CNT pull-out are observed at higher strain rates. This comprehensive analysis sheds light on the intricate mechanical behavior of microwave-processed polypropylene nanocomposites, offering insights into their potential applications and optimization strategies.

Free Vıbratıon of a Carbon Nanotube-Reınforced Nanowıre/Nanobeam wıth Movable Ends

ObjectiveThe purpose of this work is to investigate the size-dependent free vibrations of carbon nanotube-reinforced nanowires/nanobeams with movable ends. For this purpose, two movable end conditions are considered for carbon nanotube-reinforced nanowires/nanobeams with different carbon nanotube distributions. The size effect is addressed with the modified couple stress theory, which includes a material length scale parameter.MethodsIn this study, a solution approach based on the Fourier sine series and Stokes' transformation is used. With the help of this approach, both rigid and movable end conditions can be investigated. Firstly, equation sets consisting of infinite series and movable end parameters are derived. Then, eigenvalue problems are obtained for the free vibration of carbon nanotube-reinforced nanowires/nanobeams. The eigenvalues of these problems give the frequencies of the carbon nanotube-reinforced nanowires/nanobeams with movable ends.ConclusionsThe eigenvalue problems obtained in this study can be used to examine both rigid and movable end conditions. The accuracy of the problems obtained for solution is proven by various comparison studies. Then, a series of analyses are carried out for nanowire/nanobeam reinforced with carbon nanotubes, including both the size effect and the rotary inertia effect. When the frequencies of nanowire/nanobeams reinforced with carbon nanotubes are examined, it is understood that the material length scale parameter, carbon nanotube distribution, carbon nanotube volume fraction, rotational and lateral spring parameters can cause significant changes in free vibration.

Evolution of surface oxide chemistry and its effect on the electrochemical degradation behaviour of AlCoFeCuNi high entropy alloy coating incorporated with multiwalled carbon nanotubes

AlCoFeCuNi high entropy alloy (HEA) coatings containing different volume fractions of carbon nanotubes (CNTs) were electrodeposited over mild steel substrate. Phase constitution, morphological evolution, electrochemical corrosion properties and surface oxide chemistry of the coatings were investigated as a function of their CNT content and correlated. With initial incorporation of the CNTs, the surface morphology of the composite coatings became progressively finer and compact till an optimum CNT volume fraction. Higher volume fractions of CNTs led to their agglomeration which yielded rougher and defective coating morphology. Corrosion rate of the HEA coating was highly sensitive to the CNT content and at an optimum CNT volume fraction HEA-CNT composite coatings (HEA_CNT-3 coating produced from electrolyte with 10 mg/L of CNT) with lowest corrosion rate was obtained (polarization resistance: Rp = 1178.85 Ω-cm2) while the highest corrosion rate was observed for the pristine HEA coating (Rp = 225.84 Ω-cm2). The coating with highest CNT volume fraction (HEA_CNT-6 coating produced from electrolyte with 35 mg/L of CNT) exhibited the polarization resistance value of 281.80 Ω-cm2. Contact angle measurement revealed that with increase in CNT content, coating hydrophobicity increased monotonically. Analysis of the surface oxide layer of the exposed samples exhibited increase in the relative content of Co3O4, CuO, NiO, AlO(OH) oxides with the presence of CNTs. This work shows that an optimum volume fraction of CNT which produces relatively compact morphology and facilitates evolution of stabler surface oxides leads to significant enhancement in the corrosion resistance of AlCoFeCuNi HEA-CNT composite coating.

Heat transfer analysis of MHD oscillatory SWCNT/MWCNT‐H2O hybrid nanofluid flow in a channel

AbstractRegulating the thermal conductivity of the fluid in various heat exchange systems plays an important role. In this regard, the carbon nanotubes (CNTs), with their higher thermal conductivity, can enhance the heat transfer potential. The main objective of the present study is to explore the impact of suction and injection on the oscillatory flow of CNT‐based hybrid nanofluid through a channel under the influence of the magnetic field for analysing heat transfer perspectives. While developing a mathematical model of the problem, we also considered other relevant elements, such as thermal radiation for optically thin fluids and porous mediums. The behaviour of a water‐SWCNT + MWCNT hybrid nanofluid is studied concerning the volume fraction of CNTs. The governing flow equations have been solved to obtain the correct solutions for the distribution of velocities and temperatures. Graphs and tables are used to assess the impact of relevant parameters on the flow and derived quantities. Adding CNTs to a fluid reduces its temperature and velocity, making it ideal for cooling systems. However, plates exhibit a maximum heat transfer of 35.35% and 25.35%, respectively, for and . The magnetic and constant pressure parameters greatly diminish the fluid's velocity, while the thermal buoyancy forces strengthen the flow. The effectiveness of the current study is confirmed by comparing its results to those from previous investigations.

Analytical modeling of the electrical conductivity of CNT-filled polymer nanocomposites

Electrical conductivity of most polymeric insulators can be drastically enhanced by introducing a small volume fraction [Formula: see text] of conductive nanofillers. These nanocomposites find wide-ranging engineering applications from cellular metamaterials to strain sensors. In this work, we present a mathematical model to predict the effective electrical conductivity of carbon nanotubes (CNTs)/polymer nanocomposites accounting for the conductivity, dimensions, volume fraction, and alignment of the CNTs. Eshelby’s classical equivalent inclusion method (EIM) is generalized to account for electron-hopping—a key mechanism of electron transport across CNTs, and is validated with experimental data. Two measurements, namely, the limit angle of filler orientation and the probability distribution function, are used to control the alignment of CNTs within the composites. Our simulations show that decreasing the angle from a uniformly random distribution to a fully aligned state significantly reduces the transverse electrical conductivity, while the longitudinal conductivity shows less sensitivity to angle variation. Moreover, it is observed that distributing CNTs with non-uniform probability distribution functions results in an increase in longitudinal conductivity and a decrease in transverse conductivity, with these differences becoming more pronounced as the volume fraction of CNTs is increased. A reduction in CNT length decreases the effective electrical conductivity due to the reduced number of available conductive pathways while reducing CNT diameter increases the conductivity.

Nonlinear bending examination of nanocomposite cylindrical shell exposed to mechanical loads using dynamic relaxation method

In the current context, the nonlinear bending examination of a carbon nanotube reinforced composite (CNTRC) shell exposed to mechanical loading using the first-order shear deformation shell model via the dynamic relaxation (DR) procedure, is perused. The composite shell is assumed to be reinforced in the longitudinal axis. The curved morphology distribution of CNTs is considered to be functionally graded (FG) or uniform along the shell thickness. Mechanical properties of the constituents are gathered based on the modified rule of the mixture. For verification, the present numeric outcomes are compared with available references and ABAQUS finite element package. Finally, the roles of effective items including carbon nanotubes (CNTs) distributions, thickness-to-radius and length-to-radius ratios, boundary conditions, and the volume fraction of CNTs are investigated on the maximum non-dimension deflection.

Enhancing interfacial shear strength with tailored carbon nanotube orientations: A micromechanical hierarchical model of single fiber fragmentation tests

This study explores the effects of carbon nanotube (CNT) orientation on stress transfer in carbon fiber (CF) composites using the Single Fiber Fragmentation Test (SFFT). A micromechanical hierarchical model, utilizing the Finite Element Method (FEM), is developed to analyze a CF composite with a CNT-reinforced interfacial region, encapsulated within an epoxy resin matrix. The Mori-Tanaka method is utilized to calculate the effective properties of the CNT-reinforced interfacial region of the CF, taking into account different CNT orientations and volume fractions. Scenarios involving radial, longitudinal, and random CNT orientations are considered. Moreover, the study also incorporates the nonlinear plastic behavior of the epoxy matrix. A novel analytical framework that leverages FEM to compute variables such as critical length, interfacial shear strength (IFSS), and average normal stress is proposed to accomplish it. Numerical results are compared to existing experimental data for validation. For the validation of the proposed methodology, experimental data available in the literature were used. The model predictions show that specific orientations and volume fractions of CNTs have the potential to enhance IFSS. However, the enhancement in the elastic stiffness of the interfacial region, attributed to the inclusion of CNTs, does not entirely explain the improvements in IFSS observed in the experimental studies from the literature.

Low speed impact on sandwich beam with flexible core and face sheets reinforced with FG-CNTs

Purpose The purpose of this study is to model the theory of the low-velocity impact (LVI) process on sandwich beams consisting of flexible cores and face sheets reinforced with functionally graded carbon nanotubes (CNTs). Design/methodology/approach A series of parameters derived from molecular dynamics are used to consider the size scale in the mixture rule for the combination of CNTs and resin. A procedure involving the use of the first-order shear deformation theory of the beam is used to provide the displacement field of the sandwich beam. The energy method and subsequently the generalized Lagrange method are used to derive the motion equations. Due to the use of Hertz’s nonlinear theory to calculate the contact force, the equations of motion are nonlinear. Validation of the problem is carried out by comparing natural frequencies with other papers. Findings The influence of a series of parameters such as CNTs distributions pattern in the face sheets, the influence of the CNTs volume fraction and the influence of the core thickness to the face sheets thickness ratio in the issue of LVI on sandwich beams with clamped-clamped boundary conditions is investigated. The result shows that the type of CNTs pattern in the face sheet and the CNTs volume fraction have a very important effect on the answer to the problem, which is caused by the change in the value of the Young’s modulus of the beam at the contact surface. Changes in the core thickness to the face sheets thickness ratio has little effect on the impact response. Originality/value Considering the important application of sandwich structures in vehicles, aviation and ships, in this research, sandwich beams consisting of flexible core and CNTs-reinforced face sheets are investigated under LVI.

Static Buckling and Free Vibration Analysis of Aligned CNTs Reinforced Composite Plates

This work introduces an analysis of the nonlinear buckling and free vibration behavior of polymer plates reinforced with aligned carbon nanotubes using Reddy's third-order shear deformation plate theory and incorporating Theodore von Kármán's geometric nonlinearity. The polymer plates were enhanced with single-walled carbon nanotubes assumed to exhibit either uniform distribution or functionally graded distribution across the thickness. The equations of motion were established through Hamilton’s principle and then solved by the Galerkin method and Airy’s stress function for the composite plates with fully simply supported edges. The investigation focused on assessing the effects of carbon nanotube distribution, volume fraction, and geometrical parameters on the buckling load and fundamental frequency parameters of composite plates through numerical results.

Random distribution of interphase characteristics on the overall electro-mechanical properties of CNT piezo nanocomposite: Micromechanical modeling and Monte Carlo simulation

A phenomenological study is carried out to speculate the statistical impacts of the CNT/polymer interphase on the overall electro-elastic behavior of piezo-polymer nanocomposites by presenting a full-field micromechanical model. The nanocomposite system consists of carbon nanotube (CNT) and PVDF. Various statistical distributions, including Weibull, log-normal, normal, beta, and uniform distributions on the thickness and strength of the interphase are carefully assessed. The results are compared with experimental data, and satisfactory agreements are reported. It is found that, compared to the random distribution of the interphase strength, the statistical distribution of the interphase thickness has more effect on the overall electro-elastic properties. For example, for the effective longitudinal modulus, the overall coefficients of variation are 14 %, 13 %, 13.56, and 10 %, respectively, for the normal, Weibull, beta, and uniform distributions of the thickness compared with the measured experimental values. Also, the effects of the CNT content, aspect ratio, and orientation on the effective electro-elastic properties by considering the various random distributions are fully examined. Moreover, using the Monte Carlo simulation, the probability of not meeting design specification (failure probability) is evaluated at the random distributions of the interphase strength and thickness to identify the optimum CNT content for which the values of the overall properties are maximum. It is obtained that the failure probabilities are different for 5–8 % CNT volume fraction in the distributions of the thickness, and for only 5 VF% CNT in the strength distributions. For other values of the CNT content, the failure probabilities are independent of the distribution of the interphase strength and thickness.

Darcy-Forchheimer flow of MHD free convective CNTs Casson nanoliquid via a cosinusoidally fluctuating heated plate

ABSTRACT This study explores the influence of carbon nanotubes (CNTs), spanwise cosinusoidally fluctuating thermal and mass diffusion on unsteady MHD free convective flow of Casson nanoliquid via an infinite hot vertical porous plate in a Darcy-Forchheimer porous medium. The overlapping grid multi-domain trivariate spectral collocation method is used to solve the non-dimensional equations. The impact of varying physical estimators on profiles alongside skin friction factor, rate of heat, and mass transport is contemplated. It was disclosed that the velocity and skin friction factors can be maximized via strong buoyancy forces and porous permeability but minimized through strong magnetic field and the Darcy–Forchheimer relation. The temperature and rate of heat transport can be increased by higher levels of heat generation, viscous dissipation, diffusion-thermo, and radiation absorption. Conversely, these factors can be minimized with higher thermal radiation. The introduction of activation energy and nonlinear chemically reactive species is responsible for the increase in species concentration and the rate of mass transport. The velocity and temperature are enhanced with increasing CNTs volume fraction, which leads to an increment in skin friction factor and thermal transport rate. Therefore, the suspension of CNTs in conventional fluids to control the coolant level in industrial apparatuses is absolutely practical.

An Investigation of Free Vibration Characteristics of a DFG-CNTRC Thin Laminated Shell in Thermal Environment

A dynamic model of dual-functional gradient carbon nanotube-reinforced composite (DFG-CNTRC) laminated shell in a thermal gradient environment is established. The carbon nanotubes (CNTs) are supposed to be FG distribution in the functionally graded material (FGM) consisting of metal and ceramic components, and its traveling wave vibration in thermal gradient environment environments is studied. The temperature between the internal and external sides of laminated shell varies linearly. Considering the impact of the thermal environment on material properties, the orthogonal polynomials are used as admissible function, and the vibration differential equation of the DFG-CNTRC laminated shell is obtained by using the Rayleigh–Ritz method. First-order shear deformation theory (FSDT) and artificial spring technique are applied to establish a general model of free vibration of rotating DFG-CNTRC laminated shells under arbitrary boundary in the thermal gradient environment. The effects of rotational speed, the environmental temperature, the thickness of the middle layer, and volume fraction of CNTs on the traveling waves are discussed.

Free vibration of functionally graded carbon nanotube-reinforced composite beam

The purpose of this paper is to investigate the free vibration behavior of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) beam. The carbon nanotubes (CNTs) are aligned and distributed in polymeric matrix with different patterns of reinforcement. The material properties of the FG-CNTRC beam are estimated by using the rule of mixture. The trigonometric shear deformation beam theory is employed to deal with the problem. The mathematical models provided in this paper are numerically validated by comparison with some available results. New results of free vibration analyses of FG-CNTRC beam are presented and discussed in detail. The effects of the length to thickness ratio and CNT volume fraction are taken into investigation.

Natural frequency analysis of sandwich plate with auxetic honeycomb core and CNTRC face sheets using analytical approach and artificial neural network

In this paper, an analytical investigation is presented on the natural frequency analysis of sandwich plate resting on Winkler-Pasternak type elastic foundations in thermal environment. The sandwich plate consists of an auxetic honeycomb core with negative Poisson's ratio, which is assumed to perfectly bond to two carbon nanotube reinforced composite (CNTRC) face sheets to ignore potential interface effects or imperfections in bonding. The material properties of CNTRC are assumed to be temperature dependent. The volume fraction of carbon nanotube (CNT) varies through the thickness dimension according to linear functions with five different distribution patterns of CNT including UD, FG-O, FG-V, FG-Λ and FG-X. The governing equations of motion are derived based on the Reddy's first order shear deformation plate theory and Hamilton's principle, and the expression of the natural frequency is performed via Galerkin method. Artificial neural network (ANN) model is established to accurately predict the natural frequency of the sandwich plate on the basis of 1450 data points collected from analytical results. The effects of various material and geometrical parameters on the natural frequency of the sandwich plate are investigated in details.

Experimental investigation and correlation development of flow condensation with R123/MWCNTs nanorefrigerant inside a horizontal tube

The current experimental study is focused on examining the behaviour of heat transfer of pure R123 and R123/multi-walled carbon nanotubes nanofluid condensing in a smooth horizontal pipe at a range of different working conditions, like the mass velocity of about 200–500 kg/m2s, multi-walled carbon nanotubes volume fraction of approximately 0.01, 0.05, and 0.1 %, vapour quality of approximately 0.05–0.9, and saturation temperature of about 35.3 and 40.9 °C. The heat transfer coefficient of pure R123 and nanorefrigerant is compared in this investigation. According to the results, employing multi-walled carbon nanotubes improves the heat transfer coefficient for all selected volume fractions. It is observed that the heat transfer coefficient for both pure and nanorefrigerant falls as the saturation temperature rises from 35.3 to 40.9 °C. For a mass velocity of about 400 kg/m2s, 0.1 % fraction of multi-walled carbon nanotubes results in the highest heat transfer coefficient increase of 29 % compared to the base refrigerant. The mean absolute error analysis is evaluated to forecast the accuracy of the experiments by comparing the experimentally captured condensation heat transfer data with available correlations, which shows good agreement. A new correlation for flow condensation heat transfer coefficient is suggested, with an acceptable mean absolute percentage error of about 9.6 %.

Experimental study on the thermodynamic performance optimization of phase change energy storage permeable concrete

To prepare Phase Change Energy Storage Permeable Concrete (PCESPC) with excellent thermodynamic performance, it is necessary to determine the optimal volume fraction of Microencapsulated Phase Change Material (MPCM), volume fraction of Carbon Nanotubes (CNTs), and Water-Binder ratio (W/B). In this study, we utilized the response surface methodology Box-Behnken Design (RSM-BBD) in Design-Expert software to optimize the experimental design and establish regression models to investigate the effects of the three aforementioned parameters on PCESPC's compressive strength, permeability coefficient, temperature change range, and snow melting rate. This approach aims to optimize the relationship between key factors and response variables in studying complex systems, helping researchers find the optimal process conditions to achieve the best response variable results. The study revealed that the optimal formulation includes 1.39 % volume content of MPCM, 0.3 % volume content of CNTs, and W/B of 0.33. This formulation yields PCESPC with compressive strength of 20.25 MPa, permeability coefficient of 1.25 mm/s, temperature drop amplitude of 3.97 ℃, temperature rise amplitude of − 4.96 ℃, and snow melting rate of 11.40 g/min. After experimental validation, the error between the predicted results and the experimental values was found to be less than 5 %, indicating the accuracy and reliability of the optimized results. Furthermore, the introduction of two MPCM with distinct phase change temperature ranges enabled dual-temperature regulation and snow melting effects for permeable concrete pavement under both high and low temperature conditions, which can provide valuable insights for the optimization of PCESPC composition and road surface temperature control.

Thermo-electrical postbuckling behavior of carbon nanotubes-reinforced composite beams with piezoelectric layers and tangentially restrained ends

An analytical investigation on the buckling and postbuckling behavior of carbon nanotube-reinforced composite beams integrated with surface-bonded piezoelectric layers under uniform temperature rise is presented in this paper. Carbon nanotubes (CNTs) are reinforced into isotropic matrix through uniform distribution and functionally graded distributions. The properties of material constituents are assumed to be temperature-dependent and effective properties of CNT-reinforced composite are estimated using an extended rule of mixture. Equilibrium equations of the beams are established based on Euler-Bernoulli theory including von Kármán nonlinearity and solved using analytical solutions and Galerkin method. Critical temperatures and postbuckling load-deflection paths are determined using an iteration algorithm. Parametric studies are performed to examine the influences of CNT distribution and volume fraction, applied voltage, in-plane and out-of-plane conditions of the ends, slenderness, and thickness ratio of layers on the critical loads and postbuckling load carrying capacity of beams. Results reveal that CNT volume fraction and degree of in-plane ends constraint have slight and significant influences on the critical temperatures and thermal postbuckling paths, respectively. The study also finds that negative and positive voltages increase and decrease the thermal buckling temperatures of piezoelectric CNT-reinforced composite beams.