Volume Fraction Of Carbon Nanotubes Research Articles

Analysis of forced and free vibrations of composite porous core sandwich cylindrical shells and FG-CNTs reinforced face sheets resting on visco-Pasternak foundation under uniform thermal field

The radial basis function and Newmark-beta methods were used to investigate the vibrational behavior of composite sandwich cylindrical shells with porous core and functionally graded carbon nanotube. The porous core material is a kind of open-cell metal foam, whose, depending on the porosity coefficient and the core thickness, mechanical properties vary. The Hamilton principle was used to extract its motion equations. In this cylindrical sandwich shell, temperature variations are uniformly distributed and resting on the visco-Pasternak foundation with different boundary conditions. Parametric studies were presented to investigate the influence of FG porosity, temperature change, visco-Pasternak foundation, volume fraction, geometrical properties, and distribution of carbon nanotubes on natural frequencies and response dynamics of the sandwich composite cylindrical shell. The numerical outcomes express the distribution of CNTs and volume fraction play a pivotal role in the natural rates and dynamic response of the cylindrical sandwich shell. It is also perceived that there is an increase in the cylindrical shell deformation amplitude with an increase in temperature, damping, and core porosity.

Heat waves interference regarding dual-phase-lag, hyperbolic and Fourier heat conduction in CNT reinforced composites under a thermal shock

We present a framework to investigate the effects of transient heat conduction on heatwave interference and the overshooting phenomenon in carbon nanotube (CNT)-reinforced composites. Material properties of the nanocomposite are temperature and volume dependent. Different kinds of heat conduction models such as Fourier, hyperbolic or single-phase-lag (SPL), and dual-phase-lag (DPL) are considered while the media is subjected to a heat pulse or periodic thermal shock. This paper attempts to add three contributions to the existing literature: (1) using the differential quadrature method (DQM) to solve for the first time, the nonlinear DPL heat conduction equations while the materials and properties are geometry- and temperature-dependent; (2) showing the effects of the volume fraction of CNTs and their distribution on the transient heat conduction and heatwave interference; (3) demonstrating heatwave interference and the high-temperature gradient as the origins of the overshooting phenomenon. The accuracy of the present solution is confirmed by comparing it with available results from the literature.

Deflections, stresses and free vibration studies of FG-CNT reinforced sandwich plates resting on Pasternak elastic foundation

The present study covenants with the static and free vibration behavior of nanocomposite sandwich plates reinforced by carbon nanotubes resting on Pasternak elastic foundation. Uniformly distributed (UD-CNT) and functionally graded (FG-CNT) distributions of aligned carbon nanotube are considered for two types of sandwich plates such as, the face sheet reinforced and homogeneous core and the homogeneous face sheet and reinforced core. Based on the first shear deformation theory (FSDT), the Hamilton\'s principle is employed to derive the mathematical models. The obtained solutions are numerically validated by comparison with some available cases in the literature. The elastic foundation model is assumed as one parameter Winkler - Pasternak foundation. A parametric study is conducted to study the effects of aspect ratios, foundation parameters, carbon nanotube volume fraction, types of reinforcement, core-to-face sheet thickness ratio and types of loads acting on the bending and free vibration analyses. It is explicitly shown that the (FG-CNT) face sheet reinforced sandwich plate has a high resistance against deflections compared to other types of reinforcement. It is also revealed that the reduction in the dimensionless natural frequency is most pronounced in core reinforced sandwich plate.

Nonlinear deflection analysis of CNT/magneto-electro-elastic smart shells under multi-physics loading

In this article, a first attempt has been made to address the nonlinear deflection problem of magneto-electro-elastic shells reinforced with carbon nanotubes subjected to multiphysics loads like mechanical, electric and magnetic loads. In this regard, a mathematical model based on higher-order shell theory, von-Karman’s nonlinearity is derived using finite element platform. The true flexural behavior of the functionally graded carbon nanotube reinforced magneto-electro-elastic shell under the action of individual/combined multiphysics loading is captured through higher-order nonlinear terms. Meanwhile, the results of this article emphasize on understanding the influence of coupling fields in conjunction with material and geometrical parameters on the deflection of functionally graded carbon nanotube reinforced magneto-electro-elastic shells. In addition, the study provides an intensive and meticulous insight into the deflection of curved shells with respect to different shell geometry, carbon nanotube distributions, carbon nanotube volume fractions, aspect ratio, thickness ratio, shallowness ratio, and electro-magnetic loads. The study is believed to pave way for extensive further studies on these classes of materials which can prove to be instrumental in various avenues of aerospace research and development.

A molecular dynamics investigation for predicting the effect of various parameters on the mechanical properties of carbon nanotube-reinforced aluminum nanocomposites.

Carbon nanotube (CNT)-reinforced aluminum (Al) composites are being developed to replace the conventional materials due to the enhanced stiffness for more cost-effective engineering applications. In the present study, a qualitative analysis has been conducted on carbon nanotube aluminum (CNT-Al) composites to predict the effect of CNT volume fraction, diameter, and structure (zigzag, armchair) on elastic modulus, shear modulus, bulk modulus, and ultimate tensile strength (UTS) through molecular dynamics simulation. This study shows that the elastic modulus was improved by 105% compared with pure Al, for the CNT-Al composite reinforced with the (4, 4) armchair SWCNT at a volume fraction of 8.79%. The highest value of Young's modulus of 130.37GPa occurred at the volume fraction of 11.75% for zigzag SWCNT. The CNT-Al composites showed better UTS for the Al matrix reinforced with larger diameter CNT. An enhancement of 31.65% was observed in the UTS of CNT-Al composite from 4.74 to 6.24GPa with (6, 6) CNT at 0.51% volume fraction. Elastic and bulk moduli were found to improve with a higher volume fraction of CNTs. The CNT-Al composite reinforced with smaller diameter CNT's have better elastic modulus than those reinforced with larger diameter CNT for the same volume fraction. Graphical abstract Variation of Young's modulus with SWCNT volume fraction for a constant cell size of CNT-Al composite.

Thermal effects on the free vibration of joined FG-CNTRC conical-conical shells

In this paper, the effects of temperature on free vibration of carbon nanotube reinforced composite (CNTRC) joined conical-conical shells are investigated. Carbon nanotubes (CNTs) are embedded across the thickness uniformly or functionally. Material properties of the shell are assumed to be functions of temperature. To study the free vibration of shells settled in thermal environments, it requires solving the static equations. Therefore, in order to derive these equations, first order shear deformation theory (FSDT) accompanied by von Kármán types of geometrical nonlinearity are employed in Hamilton's principle. Then, initial stress resultants due to equilibrium state, are extracted via linear membrane solution. Afterward, equations of motion are derived with regard to initial deformations and stresses. With considering the equations of motion for two cones together with boundary and continuity conditions, a set of governing equations is provided. To discretize the governing equations meridionally, generalized differential quadrature (GDQ) method is proposed. The results are primarily validated via comparing them with those of relevant researches in this field. Thereafter, some studies are carried out to exhibit the significant role of temperature variations, CNT distribution patterns, CNT volume fractions, cones' angles and boundary conditions on the free vibrational behaviors of joined conical shells. For the sake of preventing buckling occurrence during the present vibration analysis, critical buckling temperature Tcr is obtained by the procedure that the natural frequency takes zero value for the lowest temperature.

The stability of composite conical shells covered by carbon nanotube-reinforced coatings under external pressures

In this study, the stability of sandwich conical shells covered by functionally graded and uniform distributed carbon nanotube-reinforced composite coatings under external pressures is carried out. The mechanical properties of the carbon nanotube and matrix are assumed to be graded through the thickness of the coatings via three types of grading rule. The basic relationships and stability equations of sandwich conical shells reinforced by carbon nanotubes are obtained employing the modified Donnell-type shell theory and generalized first-order shear deformation theory. The Galerkin procedure is employed to define expressions for the external buckling pressures. For the accuracy of the proposed formulation, the results are compared with the results that are published in the literature. It follows a systematic study aimed at checking the sensitivity of the structural response to the type of pattern and the volume fraction of carbon nanotubes in the composite coatings.

Analytical investigation on sound transmission loss of functionally graded nanocomposite cylindrical shells reinforced by carbon nanotubes

This article presents the numerical results for acoustic transmission through relatively thick functionally graded carbon nanotube-reinforced composite (FG-CNTRC) cylindrical shells. The vibration behavior of cylindrical shell is modeled using the first-order shear deformation theory (FSDT) which takes into account the transverse shear strains averaged over the wall thickness. Effective properties of materials of the shell reinforced by single-walled carbon nanotubes (SWCNTs) are estimated through a micromechanical model based on the extended rule of mixture. Furthermore, four different types of distribution of carbon nanotubes (CNTs) along the thickness direction, i.e., UD, FG-V, FG-O, and FG-X, are considered. The shell is submerged in a fluid with an external airflow and an oblique plane wave excites on the external sidewall of the shell. In order to obtain an analytical solution of sound transmission loss (STL), the motion equations of the shell and acoustic wave equations are simultaneously solved. Then, natural frequencies and STL are extracted and they are compared with those available in the literature. Finally, the obtained results are discussed to demonstrate the effectiveness of the CNT distribution, volume fraction of CNTs, shell thickness, and Mach number on STL.

Vibration control of sandwich plate–reinforced nanocomposite face sheet and porous core integrated with sensor and actuator layers using perturbation method

In this article, the vibration control of the sandwich plate reinforced by carbon nanotube in the face sheet and porous core integrated with sensor and actuator layers is investigated. The piezoelectric layers at the bottom and top surfaces of the sandwich plate play the role of the sensor and actuator. By applying the Hamilton’s principle, the governing equations of the structure are derived based on the first-order shear deformation theory. The perturbation method is used to find the relationships between nonlinear frequency and amplitude response of the sandwich plate. The effect of porosity coefficient, temperature, volume fraction of carbon nanotube, and geometric parameters on nonlinear frequency and vibration control of the sandwich plate is studied. Moreover, the influence of material type of sensor and actuator and scale transformation parameter on the nonlinear frequency and vibration control of the system is investigated. According to the obtained results, in the case of ε < 0, the system stiffness presents softening behavior, whereas in the case of ε > 0, the system stiffness becomes hardening. By considering the effect of the voltage coefficient on the vibration control and the needed time for stabilization, the results of this article can be used to design, manufacture, and control modern structures.

Nonlinear forced vibration of sandwich plate with considering FG core and CNTs reinforced nano-composite face sheets

Nonlinear vibration of sandwich plate with functionally graded material (FGM) core and carbon nano tubes reinforced (CNTs) nano-composite layers by considering temperature-dependent material properties are studied in this paper. Base on Classical plate theory (CPT), the governing partial differential equations of motion for sandwich plate are derived using Hamilton principle. The Galerkin procedure and multiple scales perturbation method are used to find relation between nonlinear frequency and amplitude of vibration response. The dynamic responses of the sandwich plate are also investigated in both time and frequency domains. Then, the effects of nonlinearity, excitation, power law index of FG core, volume fraction of carbon nanotube, the function of material variations of FG core, temperature changes, scale transformation parameter and damping factor on the frequency responses are investigated.

Advanced nanoindentation simulations for carbon nanotube reinforced nanocomposites

Mechanical properties of Carbon Nanotube (CNT) reinforced composites are obtained utilizing finite element (FE) method-based indentation simulations considering large strain elasto-plastic behavior of elements. This study includes nanoindentation simulations for chemically non-bonded CNT/matrix interface, including the length scale effect of nanocomposites. In order to investigate the mechanical properties of CNT reinforced nanocomposites, a number of FE models for nanoindentation tests have been simulated. Sample nanocomposites are examined to determine the suitable types of CNTs and their effectiveness as a reinforcement of different potential matrices. The Parametric study is conducted to obtain the influence of wall thickness, relative positioning, and volume fraction of CNT and strain hardening parameter of matrix on the mechanical properties of nanocomposites. The obtained results indicate that, properties such as modulus of elasticity and hardness of the nanocomposites are largely dependent on wall thickness of CNT and strain hardening parameter of the matrix. This study also suggests, the minimum wall thickness of CNT to avoid local buckling in nanocomposite which is required to be at least 0.2 nm for a diameter to thickness ratio of 5.0. Moreover, a matrix having a value of strain hardening parameter near 0.1 is expected to be significantly effective for nanocomposite.

On static bending of multilayered carbon nanotube-reinforced composite plates

In this paper, the bending behavior of single-walled carbon nanotube-reinforced composite (CNTRC) laminated plates is studied using various shear deformation plate theories. Several types of reinforcement material distributions, a uniform distribution (UD) and three functionally graded distributions (FG), are inspected. A generalized higher-order deformation plate theory is utilized to derive the field equations of the CNTRC laminated plates where an analytical technique based on Navier\'s series is utilized to solve the static problem for simply-supported boundary conditions. A detailed numerical analysis is carried out to examine the influence of carbon nanotube volume fraction, laminated composite structure, side-to-thickness, and aspect ratios on stresses and deflection of the CNTRC laminated plates.

Static performance of agglomerated CNT-reinforced porous plates bonded with piezoceramic faces

Bonding the upper and lower faces of a nanocomposite porous plate with piezoceramics eventuates a smart multidisciplinary plate (SMP). In the current work, the deflection and stress responses of such SMPs under static electrical voltages and mechanical loads have been presented. The middle plate of SMP is assumed to have simultaneous functionally graded (FG) dispersions of pore and nanofiller along the thickness. The enhancement parts of the nanocomposite material are assumed to be carbon nanotubes (CNTs) and their agglomerations with random orientations. The mechanical properties of such three-part nanocomposites are evaluated using Eshelby-Mori-Tanaka (EMT)'s technique. The coupled electromechanical governing equation of SMP under static loads is obtained by the estimation of displacement field with Reddy's third order theory (Reddy's TSDT) of plates. The coupled equation is also treated by developing a mesh-free solution to examine the impacts of embedding nanofillers and pores on the static electromechanical deflection and stress responses of SMPs. The results reveal that embedding pores up to around 90% of the volume of the middle plate leads to only 11.3% and 2.2% increase in mechanical and electrical deflections, respectively. Moreover, due to the formation of CNTs agglomerations, enhancing the middle plate with CNTs has a sharp positive impact on the reduction of deflections only up to some limited values of CNT volume fractions.

Vibration analysis of shear deformable carbon nanotubes‐based functionally graded conical shells resting on elastic foundations

This article deals with the vibrational behavior of composite conical shells (CCSs) reinforced with carbon nanotubes (CNTs) resting on Winkler‐ and Pasternak‐type foundations. A generalized version of the Ambartsumian's first‐order shear deformation theory (FSDT) is here proposed to handle the vibration problems for CCSs reinforced with CNTs, resting on an elastic foundation, while considering a uniform and functionally graded (FG) distribution for the reinforcement phase throughout the shell thickness. The basic equations of the problem are determined and solved in closed form by means of the Galerkin procedure. First, we check for the reliability and accuracy of the proposed formulation with respect to the available literature. It follows a systematic investigation aimed at checking the sensitivity of the structural response to the geometry, the foundation stiffness, the type of distribution, and the volume fraction of CNTs.

Vibration analysis of porous nanocomposite viscoelastic plate reinforced by FG-SWCNTs based on a nonlocal strain gradient theory

This paper investigates the size dependent effect on the vibration analysis of a porous nanocomposite viscoelastic plate reinforced by functionally graded-single walled carbon nanotubes (FG-SWCNTs) by considering nonlocal strain gradient theory. Therefore, using energy method and Hamilton\'s principle, the equations of motion are derived. In this article, the effects of nonlocal parameter, aspect ratio, strain gradient parameter, volume fraction of carbon nanotubes (CNTs), damping coefficient, porosity coefficient, and temperature change on the natural frequency are perused. The innovation of this paper is to compare the effectiveness of each mentioned parameters individually on the free vibrations of this plate and to represent the appropriate value for each parameter to achieve an ideal nanocomposite plate that minimizes vibration. The results are verified with those referenced in the paper. The results illustrate that the effect of damping coefficient on the increase of natural frequency is significantly higher than the other parameters effect, and the effects of the strain gradient parameter and nonlocal parameter on the natural frequency increase are less than damping coefficient effect, respectively. Furthermore, the results indicate that the natural frequency decreases with a rise in the nonlocal parameter, aspect ratio and temperature change. Also, the natural frequency increases with a rise in the strain gradient parameter and CNTs volume fraction. This study can be used for optimizing the industrial and medical designs, such as automotive industry, aerospace engineering and water purification system, by considering ideal properties for the nanocomposite plate.

Analytical solutions for nonlinear magneto-electro-elastic vibration of smart sandwich plate with carbon nanotube reinforced nanocomposite core in hygrothermal environment

This paper presents an analytical approach on the nonlinear magneto-electro-elastic vibration of smart sandwich plate. The sandwich plate consists of a carbon nanotube reinforced nanocomposite (CNTRC) core integrated with two magneto-electro-elastic face sheets. For core layer, three types of carbon nanotube (CNT) distribution such as FG-O, FG-V, FG-X are considered while the volume fraction of BaTiO3 − CoFe2O4 in each face sheet is chosen to be 0.5. It is assumed that the smart sandwich plate is rested on Pasternak-type elastic foundations and subjected to the combination of external pressure, thermal, electric and magnetic loads. The coupled constitutive relations are derived based on the Hamilton's principle in which the kinematic nonlinearity is defined using Reddy's higher order shear deformation theory. The analytical solutions which satisfy the boundary conditions are assumed to have the trigonometric form. The Galerkin method is used to obtain the closed form expressions of natural frequency, the relation between the frequency ratio and dimensionless amplitude and the dynamic response of the sandwich plate. The numerical results are conducted to illustrate the effect of geometrical parameters, CNT volume fraction, temperature and moisture increment, electric and magnetic potentials on the nonlinear vibration of smart sandwich plate. The reliability of present results is evaluated by comparing with the previous results based on different approach.

The forced vibration of infinitely long cylinders reinforced by carbon nanotubes subjected to combined internal and ring‐shaped compressive pressures

In this study, the forced vibration of cylinders reinforced by carbon nanotubes (CNTs) under a moving load is estimated based on the theory of oscillations. The composite cylinders reinforced with CNTs of infinite length subjected to combined action of the internal pressure and ring‐shaped compressive pressure with constant velocity. Here, we consider uniform and nonuniform reinforcement distributions, with the mechanical properties varying linearly throughout the thickness and the effective material properties are estimated by employing the extended rule of mixture. Following the formulation of the problem, the basic equations are derived and then solved in order to determine the maximum static and dynamic deflections, dynamic factors, and critical velocity of composite cylinders reinforced with CNTs. After checking the reliability of the proposed formulation and the accuracy of the results in accordance with the available literature, a systematic study is aimed at checking the sensitivity of the dynamic response to the geometry, velocity, type of distribution, and volume fraction of CNTs.

ZnCo-carbon nanotube composite coating with enhanced corrosion resistance behavior

The electrochemical behavior, surface morphology characteristics, phase constitution and microstructure of electrodeposited ZnCo (~5 wt%) coatings with five different volume fractions of multi-walled carbon nanotubes (MWCNTs) are discussed. All the coatings contained a mixture of Zn and Zn10.63Co2.34 intermetallic phases the relative fraction of which was sensitive to the amount of the MWCNTs present in the coatings. For initial MWCNT addition, the morphology became smoother while higher MWCNTs addition lead to development of surface defects. It was observed that the addition of MWCNTs into the coating matrix produced compositional homogenization. The electrochemical measurements showed that the corrosion rate of the ZnCo-CNT composite coatings decreased for initial addition of MWCNTs to reach a minimum for an optimum MWCNTs concentration, after which it increased with further MWCNTs addition. The improved corrosion resistance for the composite coating with optimum MWCNTs addition was attributed essentially to its compact surface morphology and highest intermetallic (Zn10.63Co2.34) phase fraction.

Improvement fatigue life of polymer matrix composite by reinforcement with carbon nanotubes

This work, cover an improvement in fatigue life polymer matrix composite reinforcement with Carbon Nanotubes (MWCNT), by adding the reinforcements of Carbon Nanotubes to increase the fatigue strength. Three different percentage volume fractions added to the polymer matrix 3%, 5% and 7% to investigate which composition is more efficient and power full in mechanical application. The investigation was conducted experimentally deals with fabricated the tensile and fatigue specimens and evaluate the mechanical properties and the fatigue strength using the different volume fractions of Carbon Nanotubes and numerically by using Ansys software. Experimental results are compared with those obtained numerically using the finite element technique adopting. The comparison has shown a good agreement between the two techniques with a maximum discrepancy of (6.4%). Also, the results indicate that the reinforcement of the polymer by Carbon Nanotubes increase the fatigue limit, as the volume fraction increase the improvement of fatigue life increased.

Analytical buckling and post-buckling characteristics of Mindlin micro composite plate with central opening by use of nonlocal elasticity theory

The effect of central opening on the buckling and nonlinear post-buckling response of carbon nanotubes (CNTs) reinforced micro composite plate embedded in elastic medium is considered in this paper. It is assumed that the system is surrounded by elastic medium, therefore; the influence of Pasternak foundation on buckling and post-buckling behavior are analyzed. In order to derive the basic formulations of plate the Mindlin plate theory is applied. Furthermore, nonlocal elasticity theory is applied to consider the size-dependent effect. Analytical approach and Newton-Raphson iterative technique are utilized to calculate the impact of cut out on the buckling and nonlinear post-buckling response of micro composite plate. The variation of buckling and post-buckling of micro composite cut out plate based on some significant parameters such as volume fraction of CNTs, small scale parameter, aspect ratio, square cut out and elastic medium were discussed in details. According to the results, it is concluded that the aspect ratio and length of square cut out have negative effect on buckling and post-buckling response of micro composite plate. Furthermore, existence of CNTs in system causes improvement in the buckling and post-buckling behavior of plate. Meanwhile, considering elastic medium increases the buckling and post-buckling load of system.