Nanocomposite Plates Research Articles

Mechanical and radiation shielding properties of SWCNT reinforced polymer/glass fiber fabric‐based nanocomposite containing different filler materials: A comparative study

AbstractIn this study, polymer/glass fiber fabric‐based nanocomposite plates were fabricated with 0.01%–0.1% single‐walled carbon nanotubes (SWCNTs) and filler materials (barite, magnetite, and colemanite) using a hand layup process. Mechanical properties (e.g., tensile strength, flexural strength, and Charpy impact strength), thermal conductivity, and radiation shielding properties (e.g., gamma radiation and neutron radiation) of the specimens were determined. The results revealed that the specimens containing barite and magnetite managed to exhibit adequate mechanical properties (especially Charpy impact strength). Among different filler materials used, barite‐filled specimens outperformed colemanite and magnetite‐filled specimens in terms of mechanical properties. The mechanical performance of filler‐modified specimens can be further enhanced by adopting efficient dispersion techniques to disperse filler material and SWCNTs throughout the composite plates. The thermal conductivity of barite, magnetite, and colemanite‐filled specimens (with/without SWCNTs) increased by 30.56%–60% as compared to specimens only containing SWCNTs and neat polymer, which avoids the accumulation of heat required for radiation shielding applications. Similar to thermal conductivity, specimens containing filler materials (with and without SWCNTs) provided higher gamma and neutron radiation shielding properties as compared to neat polymer‐ and SWCNT‐modified specimens. In the case of gamma and neutron radiation shielding, barite‐ and colemanite‐filled specimens provided better results, respectively.

Stress waves in a lightweight substrate plate actuated with piezoelectric layers under sinusoidal time-dependent pressures

The dynamic behavior of cantilever lightweight substrate plates actuated by surface layers of piezoceramic with a potential application as an energy harvester is presented in this paper. The utilized passive substrate is made of nanocomposite plates with embedded pores where both nanofillers and pores are functionally graded (FG) distributed. Carbon nanotubes (CNTs) are employed as the enhancement part of the substrate whereas their major distribution drawback which is CNT accumulating in some clusters has been taken into account by employing a modified Eshelby's approach for the calculation of nanocomposite's material properties. The proposed structure is assumed under a half wave of sinusoidal time-dependent pressure to model an impact load and by providing a meshless solution, its dynamic behavior in a framework of stress wave propagation analysis has been conducted. By exploring porosity and CNT effects, the achieved results revealed that there is an optimum value for porosity volume fraction which offers the highest wave frequency. Moreover, it was observed that although there is a great difference between stress waves in structures with pure polymeric and nanocomposite substrates, involving higher CNT amounts without a perfect distribution would considerably reduce the enhancement efficiency of CNTs due to accumulating CNTs in some clusters.

Practical parameter tuning toward enhancing thermomechanical shock resistance of the nanocomposite structure

As pioneer research, the authors of this study focused on the analyzing impact of thermomechanical shock load on the behavior of the circumferentially graded single-walled carbon-nanotubes reinforced (CG-SWCNTR) nanocomposite sector circular plates with fully clamped boundaries. To ensure the highest level of accuracy, the three-dimensional theory of elasticity is considered the platform to define the governing equations. To solve the time-dependent equations, the differential quadrature approach (DQA) is combined with the Laplace transform. The construction of such structures will be possible in practice in the near future based on the accurate results obtained in this study.

Numerical assessment of the nanocomposite sector annular plates with the aim of promoting their mixed-form thermal shock response

As practical research, this study assesses the resistance of the radially-graded graphene-platelets reinforced (RG-GPLR) nanocomposite annular sector plates against thermal shock. Three-dimensional declaration of the elasticity theory is the base for defining the governing equations of the system. Discrete singular convolution technique (DSCT) is applied as an efficient solution to determine the stress and defection variation of the clamped plate against the instantaneous thermal shock. For the first time, this study considers the effect of thermal shock induced by the radical temperature gradient, heat flux, and the mixed form. Laplace transform combined with the extended Dubner and Abate's technique to find the time history of the system's thermomechanical behavior. The accuracy of the solution is inspected through a comparative analysis between the present and published studies’ results. As a valuable outcome, it is revealed that the fluctuations of the system's response around their ultimate constant values would be damped faster when the applied heat flux is higher.

Thermo-elastodynamic study of the nanocomposite circular sector plates exposed to swift thermal shock

Owing to ruinous effects of thermal shocks on the nanocomposite structures, this study scrutinizes the thermal shock resistance of the poroelastic nanocomposite circular sector plates in the scheme of elasticity theory and application of the harmonic differential quadrature approach (HDQA). Due to the fact that the related studies published priorly were just able to predict the response of the simply-supported plates, the current research would be considered as the first study on the transient thermal shock response of the above-mentioned plates with fully-clamped boundary conditions. To determine the system’s time-dependent response, differential equations are translated to the Laplace domain. Then, the modified declaration of the Dubner and Abate’s technique is exploited to derive the time realization of the system’s response from the Laplace domain. The validation procedure of the current analysis is performed by comparing the outcomes with those claimed in the published researches. In order to clearly assess the system’s shock resistance against the abrupt thermal load, effect of various parameters such as thermal relaxation time (TRT), different scattering models and volume fraction of the nano reinforcement, boundary conditions, intensity of the shock, poroelastic properties of the nanocomposite, and radius to thickness ratio of the sector plate on the thermo-elastodynamic response of the system are investigated. It is revealed that the sensitivity of the system’s response to increase of TRT subsides when TRT is over an upper bond.

Semi-Analytical Solution for Thermo-Piezoelectric Bending of FG Porous Plates Reinforced with Graphene Platelets

This research is devoted to investigating the thermo-piezoelectric bending of functionally graded (FG) porous piezoelectric plates reinforced with graphene platelets (GPLs). A refined four-variable shear deformation plate theory is utilized considering the transverse shear strain to describe the displacement components. The porous nanocomposite plate is composed of polymer piezoelectric material containing internal pores and reinforced with FG GPLs. In accordance with modified distribution laws, the porosity and GPLs volume fraction are presumed to vary continuously through the plate thickness. Four GPLs and porosity distribution types are presented. By applying the Halpin–Tsai model, the elastic properties of the nanocomposite plate are calculated. The governing equations are derived based on the present theory and the principle of virtual work. The deduced partial differential equations are converted to ordinary equations by employing Levy-type solution. These equations are numerically solved based on the differential quadrature method (DQM). In order to determine the minimum grid points sufficient to gain a converging solution, a convergence study is introduced. Moreover, the accuracy of the present formulations are examined by comparing the obtained results with those published in the literature. Additional parametric analyses are introduced to investigate the influences of the GPLs weight fraction, distribution types, side-to-thickness ratio, external electric voltage and temperature on the thermal bending of FG GPLs porous nanocomposite piezoelectric plates.

Nonlinear forced vibration of thermo-electro-elastic piezoelectric-graphene composite nanoplate based on viscoelastic foundation

Nonlinear forced vibration of thermo-electro-elastic piezoelectric-graphene composite nanoplate based on viscoelastic foundation

Layerwise formulation of poroelastic composite plate under pre-buckling and thermal shock loading

The present article scrutinizes the coupled time-variant poro-thermoelasticity behavior of functionally-graded graphene reinforced (FG-GPLR) composite plates embedded in an elastic foundation, intending to provide innovative solutions to preserve operating mechanisms toward harmful impacts of thermal shock load. The nanocomposite plate is initially stressed in three different orientations and subjected to thermal shock loading. The temperature distribution is acquired by employing the celebrated energy balance equation. The analytical solving approach is utilized for differential motion equations of the system based upon substitution of the equivalent Fourier series expansion for each state variable. Eventually, mapping the structure's response from Laplace to the time domain is carried out by a modified version of the celebrated Dubner and Abates' approach. Convergence of the outcomes regarding time is monitored and certified. The acquired results record the impact of varied parameters like length to thickness ratio of the structure, distribution pattern, and weight-content of GPL on the coupled time-variant poro-thermoelastic response of the FG-GPLR composite plate. One of the main conclusions of this survey is that increasing the weight-content of GPL in the way of locating more GPL near the upper and bottom surface of the plate applies enhancing impacts on the system's resistance against detrimental consequences of thermal shocks.

Gas permeameter for polymers and nanocomposites: a new equipment

Information on the gas transport coefficients in the permeation of homogeneous semipermeable materials such as semicrystalline polymers under extreme pressures and temperatures is rarely found in the literature. Therefore, the objective of this work is to showcase innovation regarding the accuracy and usability of the medium pressure and temperature gas permeameter suitable for polymeric and polymeric nanocomposite plates built by the authors, which was tested with nitrogen at 1 MPa and 69 °C (342.15 K) permeating pure high density polyethylene samples (HDPE) and HDPE samples with added nanoclay, redoing the tests published in a previous work on the subject. The results were compared against data obtained previously and information present in the literature, validating the permeameter presented in this work, which is capable of analyzing gas permeability under the described conditions with greater accuracy and ease of operation than the previous model for the values of the transport coefficients of nitrogen permeating HDPE, demonstrating that the implemented improvements and advances were adequate, allowing the measurement of the transport properties of gases permeating polymeric and nanocomposite plates, necessary information for the design of risers for the transportation of oil and natural gas, for example.

Interdependent effects of surface and flexoelectricity on the electromechanical behavior of BNRC nanoplate

The present work deals with the static and dynamic behavior of boron-nitride (BN) reinforced piezoelectric nanocomposite subjected to mechanical load while considering flexoelectric and surface effects. Based on the modified Kirchhoff plate theory and Navier's solution, an analytical model is derived to investigate the electromechanical response of simply supported (SS) boron-nitride reinforced nanocomposite (BNRC) plates. In addition, a micromechanical model by employing the Mori-Tanaka (MT) approach is derived to investigate the effective elastic and piezoelectric properties of the BNRC lamina. The BNRC lamina is composed of BN nanofiber and polyimide matrix, such that the BN nanofibers are oriented along the 3-direction. Our outcomes reveal that the incorporation of the BN nanofiber shows a substantial enhancement in the effective longitudinal and transverse piezo-elastic coefficients of the BNRC lamina. Further, the outcomes of the analytical model by adopting the Kirchhoff plate theory illustrate that the effects of flexoelectricity and surface show significant enhancement in the stiffness of the composite at the nanoscale, although the surface effect is more pronounced when compared with the flexoelectric effect. Based on the present analysis, we observed that the effects of flexoelectricity and surface influence the static and vibrational properties of BNRC. Thus, at the nanoscale, these size-dependent properties cannot be neglected. This work presents an opportunity for the development of high-performance and efficient BNRC nanoplates.

Natural frequency prediction of functionally graded graphene-reinforced nanocomposite plates using ensemble learning and support vector machine models

Functionally graded materials (FGMs) are modern engineering materials with increasing application in various industrial fields. In this study, the free vibration behavior of graphene-reinforced FGM plate is investigated using finite element method and machine learning (ML) approaches. For this purpose, three advanced ML models including ensemble learning algorithms (bootstrap aggregation and gradient boosting) and Gaussian support vector machine are employed to predict the natural frequency of functionally graded graphene/epoxy nanocomposite plates. In this regard, first, hyperparameter optimization is carried out using Bayesian optimization algorithm. Then, regression analysis is performed using the aforementioned ML approaches. According to the obtained results, all ML models have a high coefficient of determination (more than 96%) with low mean squared error (MSE) values. However, the best performance is related to the gradient boosting method, followed by support vector machine and bootstrap aggregation, respectively. Finally, the significance degree of involved parameters on natural frequency is estimated using the Shapley values concept. The obtained results reveal that the most significant parameters affecting the natural frequency of graphene-reinforced FGM plates are clamp type, the volume fraction of graphene, followed by thickness ratio and distribution pattern, respectively.

Post buckling responses of carbon nanotubes’ fiber reinforced and nanoclay modified polymer matrix hybrid composite plate under in-plane buckling load using the higher order shear deformation theory

The buckling response of carbon nanotubes’ fibers (CNTs’ fibers) reinforced and nanoclay modified polymer matrix hybrid nanocomposite plates under in-plane buckling loads (IBLs) is studied using the efficient finite element method (FEM) based on a higher order shear deformation theory (HSDT). The conventional carbon fibers are reinforced in polymer matrix materials of cross-ply and angle-ply CNTs’ fibers reinforced and nanoclay modified polymer hybrid nanocomposite plates. The material properties are discussed using modified Halpin-Tsai relationships. An interactive MATLAB program based on FEM is developed to evaluate the critical buckling load (CBL) of a hybrid nanocomposite plate through a minimum potential energy approach. The hybrid nanocomposite plates subjected to in-plane buckling loads (IBLs) are studied in detail for their linear and nonlinear responses with respect to the critical buckling load (CBL) and variations in (a) load ratio of the laminated hybrid plate, (b) amplitude ratio, (c) carbon nanotubes’ fibers and nanoclays’ particles, (d) inplane buckling loads such as uniaxial, biaxial, shear, uniaxial with shear, and biaxial with shear, (e) stacking sequences, (f) buckling modes, and (g) length-to-diameter ratio. The results of the simulations are in fairly good agreement with the previously published sources.

Innovative statistical approach on graphical optimization and closed-form dynamic response of the poroelastic nanocomposite sandwich structure

Present research with the aid of multivariate analysis of variance explores the closed-form dynamics of the poroelastic nanocomposite sandwich plate. Additionally, graphical optimization of the system’s vibration by proper adjusting the involved parameters is provided by employing response surface methodology. p-value and F-value tests are executed to determine the contribution percentage of each parameter on the dynamics of the structure. The nanocomposite face-sheets are made of graphene-platelets reinforced polymer. The main relations governing the dynamics of the initially stressed sandwich system are defined in the background of theory known as linear poroelasticity. Bidirectional format of discrete singular convolution approach (2D-DSCA) is employed in order to determine the design-points’ dynamic performance. Validity of the applied solution procedure is tested through comparison with the outcomes of the first-rate articles. In this research, it is revealed that the graphical optimization is a reliable way to determine the proper adjustment of the parameters for achieving the optimum vibration performance. Moreover, it is observed that the aspect ratio of the plate is the most decisive factor in the free oscillation response of the sandwich plate compared with other factors whose influence are examined in the present article including GPL’s weight-fraction, GPL’s dispersion patterns, in-plane initial stresses, and the poroelasticity coefficient.

Axisymmetric Postbuckling of Functionally Graded Graphene Platelets Reinforced Composite Annular Plate on Nonlinear Elastic Medium in Thermal Environment

This study investigates the axisymmetric postbuckling of functionally graded graphene platelets reinforced composite (FG-GPLRC) annular plates resting on nonlinear elastic medium in thermal environment. Five kinds of graphene platelets (GPLs) distribution patterns including [Formula: see text]-pattern, [Formula: see text]-pattern, [Formula: see text]-pattern, [Formula: see text]-pattern, and [Formula: see text]-pattern have been considered. The nonlinear equilibrium equations and associated boundary conditions are obtained based upon the Mindlin plate theory. The governing equations are solved via the generalized differential quadrature method (GDQM). Afterwards, the direct iterative method is implemented to accomplish postbuckling loads using the buckling mode deflection. In order to confirm the accuracy of the present model, comparisons between our data with those published in the available literature are put forth. Eventually, this paper emphasizes the impact of diverse parameters such as geometrical parameters of the structure, GPLs patterns and their geometric, GPLs weight fraction, boundary conditions, elastic medium’s parameters and temperature change on the buckling and postbuckling response of nanocomposite annular plates. It can be found that elastic medium overshadows the applicability of distribution patterns and weight fraction of GPLs.

Transparent Nanocomposites Comprising Ligand-Exchanged CuInS2/ZnS Quantum Dots and UV-Cured Resin for Wavelength Converters

Quantum dots (QDs) dispersed in UV-curable resin are used for patterning in photolithography and inkjet printing. However, low affinity between the main component of UV-curable resins known as celloxide, an alicyclic diepoxy compound, and QD surface ligands with alkyl chains causes significant aggregation of QDs. In this study, the dispersibility of core/shell CuInS2/ZnS QDs with adsorbed 1-dodecanethiol and oleic acid in celloxide was improved using the ligand exchange method to prepare transparent fluorescent nanocomposites. Cyclohexyl 3-mercaptopropionate (MPACH) and 3-mercaptopropionic acid (MPA) were successfully adsorbed onto the QDs. MPACH-modified QDs (QD-MPACH) were well dispersed in the UV-curable resin, whereas MPA-modified QDs (QD-MPA) exhibited significant aggregation. Nanocomposite plates containing dispersed QDs were prepared by UV irradiation. The QD-MPACH nanocomposite plate was transparent, while the QD-MPA nanocomposite plate was turbid. The homogeneous dispersion of QD-MPACH was attributed to the similarity in the molecular structure between MPACH and celloxide. The photoluminescence (PL) peak of the QD-MPA nanocomposite occurred at a longer wavelength than that of the QD-MPACH nanocomposite. Furthermore, compared with the absolute photoluminescence quantum yield (PLQY) of the as-prepared QDs in toluene (55%), that of the QD-MPA nanocomposite was smaller (46%), and that of the QD-MPACH nanocomposite was higher (61%). An enhanced self-absorption effect was observed for the QD-MPA nanocomposite because of significant light scattering by the aggregates and concentration quenching, resulting in the PL redshift and decreased PLQY. Moreover, the PL intensity of the QD-MPACH nanocomposite was maintained at 98% of the initial value after continuous excitation-light irradiation for 5 h. The high PLQY and photostability of the QD-MPACH nanocomposite are beneficial in practical applications.

Wave Dispersion Analysis of Functionally Graded GPLs-Reinforced Sandwich Piezoelectromagnetic Plates with a Honeycomb Core

This paper studies wave propagation in a new structure composed of three layers. The upper and lower layers are made of a piezoelectromagnetic material reinforced with graphene platelets (GPLs) that may be uniformly disseminated or continuously varied throughout the thickness of the layers. To produce a lighter plate, the core layer is assumed to comprise honeycomb structures. The smart nanocomposite plate is exposed to external electric and magnetic potentials. The effective elastic modulus of the face layers of the sandwich plate is evaluated based on Halpin-Tsai model. Whereas, the mixture rule is utilized to calculate mass density, Poisson’s ratio and electric and magnetic properties of both upper and lower layers of the sandwich plate. The governing motion equations of the lightweight sandwich plate are obtained by refined higher-order shear deformation plate theory and Hamilton’s principle. These equations are solved analytically to obtain wave dispersion relations. Impacts of the geometry of plates, GPLs weight fraction, GPLs distribution patterns, piezoelectric properties, external electric voltage and external magnetic potential on the wave frequency and phase velocity of the GPLs lightweight plates are discussed in detail.

Nonlinear magneto-mechanical-thermo coupling characteristic analysis for transport behaviors of carriers in composite multiferroic piezoelectric semiconductor nanoplates with surface effect

Nonlinear magneto-mechanical-thermo coupling characteristic analysis for transport behaviors of carriers in composite multiferroic piezoelectric semiconductor nanoplates with surface effect

Two-dimensional basic cobalt carbonate supported ZIF-67 composites towards mixed matrix membranes for efficient CO2/N2 separation

Two-dimensional (2D) porous materials have great potential in high-performance gas separation membranes. Herein, we demonstrate a facile synthesis of basic cobalt carbonate supported zeolitic imidazolate framework-67 (BCoC-ZIF) nanoplates via a template conversion method in aqueous solutions. Basic cobalt carbonate nanosheets were used as the metal source and BCoC-ZIF composites with various ZIF-67 loadings were obtained through adjusting the reaction time in an aqueous solution of 2-methylimidazole. Numerous mixed matrix membranes (MMMs) are prepared with different loadings of BCoC-ZIF composite nanoplates in the polymer of intrinsic porosity-1 (PIM-1), ranging from 1 to 20 wt% of filler loadings. The typical MMM with 10 wt% loading shows a CO2 permeability of 7326 Barrer and CO2/N2 separation factor of 32.5, exceeding the latest 2019 upper bound. The improved separation performance greatly relies on the multiply synergistic effect of high CO2 adsorption capacity, alignment of 2D morphology and molecular sieving ability of BCoC-ZIF. This study may offer a new direction for the rational design of MMMs for gas separation applications.

Wave Propagation in Smart Sandwich Plates with Functionally Graded Nanocomposite Porous Core and Piezoelectric Layers in Multi-Physics Environment

This research provides a mathematical model and solution for investigating wave propagation in graphene platelets (GPLs)-reinforced functionally graded (FG) metal foam plates integrated with piezoelectric actuator and sensor layers resting on an orthotropic visco-Pasternak medium in magneto-electro-thermo environment. The FG porous nanocomposite core and the actuator piezoelectric layer are exposed to steady magnetic and electric fields, respectively. The electric potential between two piezoelectric layers is governed by a proportional-derivative controller. The Halpin–Tsai micromechanics model and the Kelvin–Voigt model are adopted to express the effective elastic modulus of the FG porous nanocomposite core and material viscoelasticity of the core and piezoelectric layers, respectively. The governing equations of smart FG porous nanocomposite plates under thermal environment are derived grounded on the refined third-order shear deformation theory. Upon the validated theoretical model, the wave velocities and frequencies in plates are obtained by solving governing equations analytically. Finally, the effects of material viscoelasticity, porosity distribution and coefficient, GPL distribution and weight fraction, the plate and GPL geometries and external environment on wave propagation characteristics are demonstrated comprehensively. This work provides guidance on tunable control of wave propagation in smart sandwich plates affected by complex external environments.

Hygrothermal Buckling of Smart Graphene/Piezoelectric Nanocomposite Circular Plates on an Elastic Substrate via DQM

This paper aims to study the hygrothermal buckling of smart graphene/piezoelectric circular nanoplates lying on an elastic medium and subjected to an external electric field. The circular nanoplates are made of piezoelectric polymer reinforced with graphene platelets that are uniformly distributed through the thickness of the nanoplate. The material properties of the nanocomposite plate are determined based on the modified Halpin-Tsai model. To capture the nanoscale effects, the nonlocal strain gradient theory is applied. Moreover, the principle of virtual work is employed to establish the nonlinear stability equations in the framework of classical theory. The differential quadrature method is utilized to solve the governing equations. Among the important aims of the paper is to study the influences of various parameters such as graphene weight fraction, elastic foundation parameters, external applied electric field, humid conditions, and boundary conditions on the thermal buckling of the smart nanocomposite circular nanoplates. It is found that the increase in graphene components and elastic foundation stiffness enhances the strength of the plates; therefore, the buckling temperature will increase.