Nanocomposite Face Sheets Research Articles

Vibration analysis of asymmetric sandwich rotating FG porous discs coated with agglomerated nanocomposite facesheets

Vibration analysis of asymmetric sandwich rotating FG porous discs coated with agglomerated nanocomposite facesheets

Dynamic Response of Advanced Lightweight Porous Plates Integrated with Nanocomposite Face Sheets Resting on Elastic Substrate

This study centers on the analysis of a scale-dependent microplate configuration characterized by a porous core enveloped by nanocomposite patches embedded with graphene nanoplatelets. The microplate’s behavior is explored within a humid environment to comprehend the effects of moisture variations on its dynamic performance. Additionally, the microplate rests upon a Kerr foundation, a three-parameter elastic substrate. The material properties of all three layers are contingent upon thickness. To enhance precision, an innovative quasi-three-dimensional shear and normal trigonometric theory is employed, elucidating the kinematic interrelations of the microstructure. Notably, this novel theory accommodates the presence of transverse normal strain. For a comprehensive analysis of size influences, the modified couple stress theory is harnessed. This theory integrates a material length-scale parameter to anticipate outcomes at the micro-scale. By invoking Hamilton’s principle, differential motion equations are deduced and subsequently solved analytically. The investigation centers on probing the consequences of varied parameters on the natural frequencies. The findings underscore that the incorporation of GPLs amplifies the microplate’s stiffness, thus elevating its natural frequencies. In contrast, an escalation in the porosity index leads to a reduction in natural frequencies.

On the vibrational behavior of variable thickness FG porous beams with graphene-reinforced nanocomposite facesheets

On the vibrational behavior of variable thickness FG porous beams with graphene-reinforced nanocomposite facesheets

Analytical model of low-velocity impact penetration of sandwich panels with metal foam core and nanocomposite face sheets

This paper investigates the low-velocity penetration dynamic response of metal foam core sandwich panels with composite face sheets reinforced by nanoparticles. Based on the experimental results, an energy model is developed to predict contact force, impactor displacement, energy absorption, mechanisms of impact damage, and failure modes. An elastic–plastic–rigid (E–P–R) model is used to derive the energy absorbed by the metal foam. A stress function in terms of density ratio and strain is considered to predict the compression behavior of metal foam. The effect of nanoparticles investigated by the Halpin Tsai model. The analytical prediction is compared with the results of the experimental test and a reasonable agreement has been observed. The tested sandwich panel consisted of an aluminum foam core and an epoxy/carbon fiber face sheet reinforced with reduced graphene oxide (RGO). This model is useful for improving the design of sandwich panels with carbon fiber composite face sheet reinforced with nanoparticles and aluminum foam core. The results of impact test showed the addition of reduced oxide graphene increased the value of the first peak load by about 15%, the second peak load by about 36% and the amount of energy absorption in sandwich panel by about 18%. The radios of delamination and debonding reduced by 47% and 17.5%, respectively, compared to the sample without nanoparticles.

Flutter analysis of a cantilever trapezoidal sandwich plate with an auxetic honeycomb core and three-phase nanocomposite face sheets subjected to yawed supersonic gas flow

Flutter analysis of a cantilever trapezoidal sandwich plate with an auxetic honeycomb core and three-phase nanocomposite face sheets subjected to yawed supersonic gas flow

Nonlinear free vibration modeling of anisogrid lattice sandwich plates based on a weak formulation analysis

This research examines the geometrically nonlinear free vibrations of a type of sandwich plate. This plate consists of an anisogrid lattice core and two nanocomposite face sheets. The lattice core is made up of a set of straight and oblique ribs with rectangular cross-sections that meet at nodes that are not all in the same place (anisogrid nodes). The nanocomposite skins are reinforced with carbon nanotubes (CNTs) based on the various functionally graded models. The displacement field of the sandwich plate is estimated based on the third-order shear deformation plate theory. Also, the nonlinear von-Kármán strain–displacement relations are used. Based on the Hooke and Hamilton laws, the motion equations of the system for nonlinear free vibrations are derived in a weak form. Then, the nodal weak formulation method based on the Lagrange interpolation functions and Gauss–Lobatto–Chebyshev node distribution, for the first time, is employed to calculate the time-dependent equations. The residuals of the obtained equations are minimized by the Galerkin method. Next, a displacement control iterative technique is applied to compute the nonlinear frequency of the sandwich plate. The effect of anisogrid lattice core characteristics and nanocomposite face sheets properties on the linear and nonlinear frequencies and also mode shapes are examined in the results.

Static Response of Nanocomposite Electromagnetic Sandwich Plates with Honeycomb Core via a Quasi 3-D Plate Theory

This article investigates the static analysis of functionally graded electromagnetic nanocomposite sandwich plates reinforced with graphene platelets (GPLs) under hygrothermal loads. The upper and lower layers of nanocomposite face sheets are made of piezoelectromagnetic material with randomly oriented and uniformly disseminated or functionally graded (FG) GPLs throughout the thickness of the layers, while the core layer is made of honeycomb structures. The effective Young’s modulus of the face sheets of the sandwich plate is derived with the aid of the Halpin–Tsai model. While the rule of mixtures is incorporated to compute Poisson’s ratio and electric-magnetic characteristics of the sandwich plate’s upper and lower layers. The governing equations are obtained by a refined quasi-3-D plate theory, with regard to the shear deformation as well as the thickness stretching effect, together with the principle of virtual work. Impacts of the various parameters on the displacements and stresses such as temperature, moisture, GPLs weight fraction, external electric voltage, external magnetic potential, core thickness, geometric shape parameters of plates, and GPLs distribution patterns are all illustrated in detail. From the parameterized studies, it is significant to recognize that the existence of the honeycomb core causes the plate to be more resistant to the thermal condition and the external electric voltage because of the weak electricity and thermal conductivity of the honeycomb cells. Consequently, the central deflection decreases with increasing the thickness of the honeycomb core. Moreover, with varying the external electric and magnetic potentials, the deflection behavior of the sandwich structures can be managed; raising the electric and magnetic parameters contribute to an increment and decrement in the deflection, respectively.

Numerical solution hybridized by machine-leaning-based algorithm to provide an efficient method for analyzing thermomechanical shock behavior of the circumferentially-graded graphene-plates reinforced composite sandwich panel

The present research bridges the gap between a numerical solution with efficient machine-learning-based algorithms to provide a strong platform for predicting thermomechanical shock behavior of the sandwich cylindrical panels with polymer-made core and circumferentially-graded graphene-plates reinforced (CG-GPLR) nanocomposite face-sheets. The comprehensive declaration of the elasticity theory is considered to establish the governing equations of the system in three orthogonal directions. The well-known Lord-Shulman heat transfer theorem is implemented to present the time-variant nature of the system’s heat. The differential quadrature method (DQM) is used as a numerical approach to solve the spatial dependency of the governing differential equations. While the Laplace transform solves the time dependency of the governing differential equations. In order to decline the computational cost of predicting the time-variant analysis of the thermomechanical shock response of the system, an efficient machine-learning-based algorithm is employed in a way that it only requires the thermomechanical shock information of the selective set of points known as the training set. After completion of the training procedure, this machine-learning predictor can easily predict the thermoelastic response of all points included either as the train set or a new point. Validation of the applied solution is performed through a comparative process between the present results with those determined in the published literature. The results of this study are in excellent compatibility with those obtained in a solo numerical solution.

Natural Frequencies of Soft-Core Composite Sandwich Plates Reinforced by FG Graphene Platelets

Superior mechanical properties such as ultrahigh stiffness and strength along with amazing physical properties have led to the use of nano graphene platelets (GPLs) as a reinforcement in polymer composite structures such as sandwich plates. In this research, free vibration analysis of rectangular sandwich plates with functionally graded (FG) GPL-reinforced face sheets and a soft core is investigated. A high-order three-layer accurate sandwich plate theory is employed to model the soft-core sandwich structure. Third order shear deformable plate theory is applied for functionally graded graphene nano-composite face sheets while second and third order polynomials are used for displacements of the soft core. In this theory, the transverse flexibility of the core as well as the continuity conditions of transverse shear stresses are assumed. Hamilton’s principle is applied to extract the motion equations and the corresponding analytical solutions are presented. The effects of materials properties and geometrical parameters on the natural frequencies of the sandwich plates are studied. A comparison of the present results in particular cases with those of published studies confirms the accuracy of the present analysis. Results show that the natural frequencies of the sandwich plates are enhanced by reinforcing the face sheets with GPLs.

APPLICATION OF GDQ METHOD FOR FREE VIBRATION BEHAVIOR OF AN AUXETIC SANDWICH BEAM WITH FG CNT-REINFORCED NANOCOMPOSITE FACE SHEETS RESTING ON AN ELASTIC SUBSTRATE

In this study, the free vibration behavior of an embedded sandwich beam consisting of an aluminum auxetic core and two polymer nanocomposite face sheets reinforced with carbon nanotubes (CNTs) was investigated. The CNTs were dispersed along the thickness of the face sheets through various functionally graded (FG) and uniformly distributed (UD) patterns (i.e., FG-X, FG-V, FG-O, and UD). In addition, the structure was embedded on a Winkler-Pasternak elastic substrate in order to make the problem more realistic. The effective material properties of the face sheets and the core were estimated using the extended rule of mixtures and the relations of the auxetic materials, respectively. Next, the governing differential equations were derived based on the incorporation of the first-order shear deformation theory and Hamilton's principle. To obtain the natural frequencies of the structure, the differential equations were solved by implementing the generalized differential quadrature method, which is a well-known numerical strategy. In addition, the results were validated by comparing them with the results obtained in a reputed literature study, in which perfect agreement was achieved. Finally, the influences of various parameters such as the length-to-thickness ratio, cell inclined angle, substrate parameters, CNT volume fractions, various boundary conditions, and core-to-face sheet ratio on the first natural frequency of the sandwich beam were investigated.

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.

Multi-scale modeling and numerical analysis of sandwich beams with FG auxetic 3D lattice cores and GRC face sheets subjected to drop-weight impacts

Auxetic metamaterials possess enhanced impact resistance and hence are the ideal core of sandwich structures. Here we present the enhancement of the drop-weight impact resistance of composite sandwich beams with nanocomposite facesheets by taking advantage of auxetic 3D lattice cores with FG (functionally graded) configurations. 2D and 3D lattice metamaterials with negative Poisson’s ratios (NPRs) were modeled, analyzed, and compared. Furthermore, the 3D lattice cores were designed to possess four FG patterns along the thickness direction. The mechanical properties of graphene reinforced composites (GRCs) were determined by means of micromechanical modeling according to the extended Halpin-Tsai model. In view of shape changes of lattices due to the localized deformation, full-scale finite element modeling is necessary, followed by nonlinear analysis. Compared with a re-entrant honeycomb core having the same relative density, the auxetic 3D lattice core can lead to even better resistance. Moreover, FG configurations are proven to have different effects on the impactor displacement and local transient thickness decrease of sandwich beams subjected to low-velocity impacts. Our results demonstrated the advantages of FG auxetic 3D lattices, and are expected to be beneficial to further studies and instructive for practical applications.

Transient response analysis of sandwich composite panel

In order to introduce a novel way relied on enhancing structural design as well as utilizing advanced material for protecting nonmetallic structures from detrimental impacts of transient thermal shock, this research analyzes the transient coupled thermo-elasticity response of the sandwich cylindrical panel with nanocomposite face-sheets strengthened with the functionally graded distributions of graphene-platelets affected by thermal shock loading. To determine the performance of the simply-supported system in the content of the time-altering stresses and deflections, the analytical solving approach, according to the broadly-known Navier technique, is applied to the governing equations developed on the bases of the exact theory of elasticity. It is considered that the internal surface of the panel is thermally isolated, while the outer surface is affected by thermal shock. The energy balance relation specified for this thermal boundary condition is solved to acquire the temperature gradient. Inverting the Laplace transform would be done with the aid of Dubner and Abates’ technique to designate time-history of displacements, shear stresses, and temperature distribution. The Halpin-Tsai micromechanics adjusted for nanocomposites is utilized to calculate thermoelastic properties of the nanocomposite face-sheets. The obtained numerical outcomes revealed the growth of the geometrical factor called mid-radius to thickness ratio leads to higher ultimate temperature and lower transverse shear stress.

Modified couple stress-based nonlinear static bending and transient responses of size-dependent sandwich microplates with graphene nanocomposite and porous layers

This paper investigates the nonlinear static bending and dynamic transient responses of the rectangular and circular sandwich microplates composed of functionally graded graphene nanocomposite (GNC) face sheets and a porous polymeric core layer based on the modified couple stress theory (MCST) within the isogeometric analysis (IGA) framework. The four-variable higher-order shear deformation refined plate theory (RPT) and the von Kármán large deflection assumption are synthetically employed to describe the kinematics of the microplate. The nonlinear governing equations of motion are derived from the Hamilton’s principle. The nonlinear bending problem is solved by the Newton–Raphson technique under a displacement criterion strategy, while the dynamic responses under transient loads are obtained by the Newmark integration scheme in conjunction with Newton–Raphson iterative procedure. Comparisons are carried out to test the accuracy of iteration procedure in present formulation and the reliability in capturing small scale effect of present model. Obtained outcomes reveal that raising the material length scale (MLS) parameter and volume fraction index of graphene nanofillers both leads to reductions in nonlinear static deflections, dynamic amplitudes of deflection and periods of motion. The examples for porosity coefficient show that embedding pores in core layer leads to slight changes in terms of static and dynamic responses and an improvement in weight reduction of the sandwich microplate.

Forced vibration analysis of a micro sandwich plate with an isotropic/orthotropic cores and polymeric nanocomposite face sheets

In this study, the forced vibration analysis of a micro sandwich plate with an isotropic/orthotropic cores and polymeric nanocomposite face sheets is taken into account based on first order shear deformation theory (FSDT). The core of this plate is considered as five isotropic Devineycell materials (H30, H45, H60, H100 and H200) and an orthotropic material, while facesheets layers are as polymeric matrix reinforced by carbon nanotubes under temperature-dependent and hydro material properties on the elastic foundations. The governing equations of motion are derived using the Hamilton's principle and then solved by analytical method. Also, the effects of different parameters such as size dependent, side ratio, volume fraction, various material properties of cores and facesheets and temperature and humidity changes on the dimensionless frequency are investigated. It is shown from the results that the dimensionless frequency for CT is lower than that of for MSGT. Also, it is presented that the least amplitude oscillation is related to the modified strain gradient theory due to higher stiffen. It is illustrated that the dimensionless frequency for Devineycell H200 is highest and lowest for H30. The results of this research can be used in aircraft, automotive, shipbuilding industries and biomedicine.

A comprehensive computer simulation for frequency analysis of the annular system with a honeycomb core and angle-ply multiscale hybrid nanocomposite face sheets

The honeycomb structures, due to minimal density, relative high out-of-plane compression properties, and out-of-plane shear properties, have attracted a lot of attention. Regarding this issue, in the current research, fundamental frequency analysis of the annular plate with two angle-ply multiscale hybrid nanocomposite face sheets and a honeycomb core is investigated. Halpin-Tsai as well as Hamilton’s principle, are presented for obtaining the effective material properties and governing equations of the presented composite system. For modeling the thermal environment, three-kind of thermal loading is presented. Also, the current structure is covered with the Kerr elastic foundation. The generalized differential quadrature method is presented for obtaining the exact fundamental frequency of the annular plate with two angle-ply multiscale hybrid nanocomposite face sheets and a honeycomb core. Finally, the result section is given to illustrate the influences of two angle-ply multiscale hybrid nanocomposite reinforcement, the geometry of honeycomb core, thermal loading, elastic foundation, the weight fraction of nanocomposites, and structural parameters of the annular plate on the fundamental frequency of the annular plate with two angle-ply multiscale hybrid nanocomposite face sheets and a honeycomb core. The outcomes of the current report show that for the clamped edge in the boundary conditions and each increasing is a reason for falling down the frequency of the annular plate with a honeycomb core. Another consequence is that the impact of temperature changes on the frequency of the disk is hardly dependent on the fiber angle.

Vibration analysis of a sandwich cylindrical shell in hygrothermal environment

Abstract The sandwich structures are three- or multilayered structures such that their mechanical properties are better than each single layer. In the current research, a three-layered cylindrical shell including a functionally graded porous core and two reinforced nanocomposite face sheets resting on the Pasternak foundation is used as model to provide a comprehensive understanding of vibrational behavior of such structures. The core is made of limestone, while the epoxy is utilized as the top and bottom layers’ matrix phase and also it is reinforced by the graphene nanoplatelets (GNPs). The pattern of the GNPs dispersion and the pores distribution play a crucial role at the continuous change of the layers’ properties. The sinusoidal shear deformation shells theory and the Hamilton’s principle are employed to derive the equations of motion for the mentioned cylindrical sandwich shell. Ultimately, the impacts of the model’s geometry, foundation moduli, mode number, and deviatory radius on the vibrational behavior are investigated and discussed. It is revealed that the natural frequency and rotation angle of the sandwich shell are directly related. Moreover, mid-radius to thickness ratio enhancement results in the natural frequency reduction. The results of this study can be helpful for the future investigations in such a broad context. Furthermore, for the pipe factories current study can be effective at their designing procedure.

On the dynamics of FG-GPLRC sandwich cylinders based on an unconstrained higher-order theory

In the present paper, a novel unconstrained higher-order theory (UCHOT) is applied to analyse the free vibration of cylindrical sandwich shells with nanocomposite face sheets reinforced with graphene platelets. UCHOT considers the shear and thickness deformations. It is assumed that the cylinder includes a soft core which embedded between functionally graded graphene platelets reinforced composites (FG-GPLRC). FG-GPLRC face sheet consists of several laminas that the GPL weight fraction is modified layer to layer based on the various functionally graded (FG) patterns. The Winkler-Pasternak elastic foundation is located at the inner surface of the shell. Highly coupled motion equations are solved by a semi-analytical approach. This approach is blended of the generalized differential quadrature and trigonometric expansion (TE-GDQ) methods. Solving the obtained eigenvalue problem, corresponding frequencies to the cylindrical sandwich shell are achieved. In the results part, comparison studies are carried out to indicate the validity and performance of the selected theory and solution method. Afterward, some parametric results are demonstrated to investigate the impacts of shell theory order, geometrical parameters, FG model, elastic foundation parameters, and boundary conditions on the frequency response of the mentioned structure.

Size-dependent vibration analysis of fluid-infiltrated porous curved microbeams integrated with reinforced functionally graded graphene platelets face sheets considering thickness stretching effect

Size-dependent vibration analysis of three-layered fluid-infiltrated porous curved microbeams, which are integrated with nanocomposite face sheets, is provided in this work. The effect of the fluids within the pores of the core is taken into consideration and the core’s thermomechanical properties vary across the thickness based on three different patterns. Also, the face sheets are made from epoxy, which are reinforced by graphene platelets as lightweight and high-stiffness reinforcements. Graphene platelets dispersion patterns are also considered, which obey three different functions, namely parabolic, linear, and uniform. Moreover, effective thermomechanical properties of the face sheets are determined with the aid of ERM and Halpin–Tsai micromechanical models. The microstructure is under thermal load and it is rested on Pasternak elastic foundation. In the polar coordinate system, the strains are determined for deep curved beams that lead to more accurate results. Based on a refined higher-order shear deformation theory, which includes four variables and considers the thickness stretching effect, and employing the modified couple stress theory for accounting the size effect, the differential motion equations are derived and via an analytical method, they are solved. A verification study is conducted by neglecting some parameters and after that, the results are presented and discussed in detail. It is seen that the porous core and nanocomposite face sheets material properties have significant effects on the vibrational response of the under consideration model. Up to now, no similar work in the available literature has been found, therefore, the results of this study can be considered as a benchmark for future ones. The outcomes of this study may help to design more efficient structures with the desired properties.

RETRACTED ARTICLE: Dynamic simulation of moderately thick annular system coupled with shape memory alloy and multi-phase nanocomposite face sheets

The current research work analyzes dynamics of a sandwich disk which is gently thick. The mentioned sandwich structure has honeycomb core, a couple of middle layers having fibers of shape memory alloy (SMA), and a couple of external layers of multi-scaled hybrid nanocomposite (MHC) considering in-plane force. The core in the shape of honeycomb is manufactured of aluminum due to its high stiffness and less density compared with other materials. Applying energy methods called the principle of Hamilton, we obtained governing motion equations of the mentioned structure and solved them using First-order shear-deformation-theory (FSDT), as well as generalized-differential-quadrature-method (GDQM), respectively. To layers’ joint, the compatibility equations have been taken into account. Then, a parametric mathematical manipulation has been conducted to analyze the impacts of fibers of SMA, boundary conditions (BCs), internal loads, honeycomb network angle, ratio of external to internal radiuses, ratio of thickness to length of the honeycomb, weight fraction of CNTs, angle of fibers, ratio of honeycomb to face-sheet thickness on the frequency of the multi-phase sandwich disk. The outcomes derived reveal that for any amount of internal pressure and each BCs, the relation of the honeycomb’s thickness ratios to MHC layer ( $${h}_{H}/{h}_{t}$$ ) and sandwich structure’s frequency is similar to quadratic function. Further results show that the effects of the fibers’ angle on the frequency can be ignored for larger $${h}_{H}/{h}_{t}$$ amounts.