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In this paper, the simple refined plate theory (S-RPT) is extended for the analysis of the bending and buckling behaviours of functionally graded graphene platelets reinforced composite (FG-GPLRC) plates supported by local elastic foundations under different boundaries. For the first time, an analytical method for determining the location of the local elastic foundation distribution by simple integration is extended to the analysis of the bending and buckling behaviour of plates. The method avoids complex calculations compared to previous methods for determining the position of the elastic foundation. Compared with other simplified plate theories, the displacement pattern of S-RPT is able to reflect the interrelationship between the gradient material properties and the displacement distribution along plate's thickness. The material properties of FG-GPLRC plates are affected by temperature. Using the static equilibrium method, the plate equilibrium equations are derived by directly integrating the three-dimensional elastic equations along the plate cross section. Galerkin's method is used to solve the governing equations. The accuracy of S-RPT under different boundary conditions and the accuracy of the analytical method for determining the location of the elastic foundation are verified by comparing the numerical results with the existing literature. Finally, the effects of different distribution patterns, weight fractions of GPLs, thickness ratios, aspect ratios, boundary conditions, temperature, elastic foundation distribution patterns, and elastic foundation parameters were investigated in detail. [ABSTRACT FROM AUTHOR]

In this paper, free vibration of rotating functionally graded (FG) porous eccentric semi-annular (ESA) and eccentric annular (EA) plates reinforced with graphene nanoplatelets (GPLs) in a thermal environment is solved with the help of transformed differential quadrature method (TDQM). Symmetrical and asymmetrical distributions are considered for both the porosity and the graphene nanoplatelets; the estimation of the Young's modulus is conducted by the model of Halpin–Tsai. A higher-order shear deformation theory is considered as the basis for the employment of the Hamilton's principle for the derivation of both the initial equations of the plates-up to the dynamic equilibrium point and the oscillation phenomena afterward. The method of TDQ utilizes a conformal mapping in order to obtain the DQ weighting coefficients and then discretizes the partial differential equations of the motion, as well as the boundary conditions; this discretization takes place in the physical domain directly. The results indicate that the employed numerical approach is advantageous in high solution accuracy in addition to fast convergence rate. Furthermore, the variation of the natural frequencies of the FG plates with different boundary conditions is investigated by taking into account the influences of several parameters: the geometry, such as eccentricity, thickness ratio, radius ratio; the material, such as the type of porosity and GPLs, the porosity parameter and the weight fraction of GPLs, and other parameters, such as temperature difference and rotating speed. [ABSTRACT FROM AUTHOR]

In this paper, for the first time, the deep learning technique of the artificial neural network method is used to determine the free vibration parameters of the rectangular bistable composite plates. For this purpose, first, the static and free vibration behaviours of a cross-ply bistable composite plate are studied using analytical, finite element and experimental methods. By comparing them, it is turned out that there is a considerable difference among obtained natural frequencies so that the analytical method is only able to determine the fourth natural frequency and cannot estimate the first three natural frequencies. To solve this problem, the deep neural network is employed to model the modal parameters of the bistable laminate as an explicit mathematical relationship that can be generalized to the other bistable composite plates. This mathematical relation makes it possible to obtain the natural frequencies in each of the stable configurations based on the geometric dimensions of the plate. In the following that, the inverse problem method is considered and the mode management capability is investigated. A fast swarm intelligence algorithm called firefly algorithm is used to optimize the optimization function of the mode management problem. Mode management using the evolutionary algorithm provides the appropriate physical dimensions of the plate according to the scenarios for natural frequencies arrangement. The results are validated by comparing them with those obtained by the finite element method and experiment test, which results show that this method estimates the modal parameters with high accuracy. The method used in this paper can also be applied to determine the modal parameters of other morphing structures. [ABSTRACT FROM AUTHOR]

In this paper, a new bending model for composite laminated shells is proposed based on the refined zigzag theory. This new model is superior to the previous shell models based on the first-order shear deformation theory (FSDT) by introducing in-plane linear zigzag functions along the thickness direction, such that the shear correction coefficients can be omitted. In the present formulation, the bending equilibrium equations and boundary conditions of composite laminated shells are established by the virtual work principle. Without losing generality, Navier series solutions are used to describe the static properties of the composite laminated shells. In order to evaluate the effectiveness and performance of this new model, numerical examples are carried out to discuss the effect of the lamination schemes and geometric parameters on the static properties. In addition, the results are compared with the three-dimensional (3D) elastic theory and FSDT as well as the highly accurate theories in the literature to examine the accuracy. It is observed that the present model not only has the high accuracy of the high-order or other highly accurate models, but also has the intrinsic linear terms of the first-order models, such that it is very suitable for the future deducing finite element method to analyze the large-scale laminates with high computational efficiency. Therefore, the present new model can be a good candidate for engineering applications. [ABSTRACT FROM AUTHOR]

In this paper, a boundary node method is presented to study wave propagation in laminated composite plates. The Zig-Zag theory of Cho and Parmerter is used for deriving the governing equations of laminated plates. To the best of the authors' knowledge, this study is the first one employing the theory in non-stationary dynamic plate problems addressing wave propagation issues. For this theory, there is no information about the Green's functions and thus the presented method can be considered as an alternative to the boundary integral method. With the use of exponential basis functions (EBFs), the response of the structure is first found in the frequency domain and finally the time-domain response is obtained using inverse Fourier transformation. The EBFs are found so that they satisfy the governing equations in the frequency domain. For the first time, in this paper, we shall present explicit relations for the EBFs in the frequency domain for Cho and Parmerter's Zig-Zag theory. The coefficients of the EBFs are found through the collocation of the boundary conditions. The dynamic analysis of some composite laminated plates is presented, and the results are compared to those obtained from the dynamic analysis of two-/three-dimensional finite element method (FEM). We shall discuss the capabilities and limitations of the theory and the solution method. The capability of the method, in the analysis of problems excited by high-frequency loads, is shown in the solution of wave propagation problems for which the FEM needs excessive number of elements and thus it is practically impossible to be applied. [ABSTRACT FROM AUTHOR]

In this paper, a mathematical procedure is elaborated based on large deformation, finite element and perturbation methods for thermo-large amplitude analysis of anisotropic laminated and sandwich FGM plates with temperature-dependent properties. Nonlinear thermal dependence distribution following a power law is adapted. Various types of multilayered composite plates with position and temperature-dependent material properties are considered. Mathematical formulations and explicit relationships are presented in the frame of finite element methods. The structure is subjected to linear and uniform temperature variations. The temperature and the displacement are expanded in power series with unknown terms, and the numerical solution is obtained by the finite element method. The homotopy method is used for nonlinear thermal buckling, and a continuation procedure is elaborated for nonlinear thermal–displacement responses. The nonlinear thermal critical buckling load is first computed and the postbuckling equilibrium path of FGM and laminated plates under thermal loading is investigated. Temperature-dependent properties and geometry effects as well as boundary conditions on the nonlinear thermal buckling and postbuckling behaviors are analyzed. [ABSTRACT FROM AUTHOR]

This paper aims to conduct the free vibration analysis of single-layer and laminated composite plates with multiple cutouts based on the scaled boundary finite element method (SBFEM) incorporated with the precise integration method (PIM) and the technique of the degree of freedom transform. It is applicable to a variety of shaped plates containing cordiform, circular and other complicated cutouts. The key equations are formulated built on the two-dimensional model, and the discretization is carried out in terms of only three translational displacement components as the basic unknowns. The high-order spectral elements are applied in the proposed technique to accurately simulate the arc boundaries of cutouts. Characterized by the important semi-analytical feature of the SBFEM, responses of the transverse free vibration are accurately explored. The derivation of governing equations strictly follows the 3D theory of elasticity without introducing any assumptions. The general solution of the SBFEM key equation is in the form of the matrix exponent, which is calculated by the PIM. As a type of highly precise approach, the PIM is introduced to create the global stiffness matrix from the analytical exponential matrix, which can make sure the eigensolutions with enough accuracy. Aided by the methodology of the kinetic energy formula, the global mass matrix of the perforated plate structure is constructed. According to the thin plates, the degree of freedom transform is employed to lower the dimensions of eigenvalue equation and thus improve the computational efficiency. Numerical examples of flexible square and circular plates with various cutouts reveal that excellent agreement is achieved between the natural frequencies predicted by the developed method and those from other methods and exact solutions. Furthermore, the effect of boundary conditions, skew angles, thickness-to-length ratios and sizes of cutouts on distributions of vibration frequencies is discussed. [ABSTRACT FROM AUTHOR]

This paper studies the free vibration behavior of hybrid laminated plates using a layer-wise formulation. The laminated structures are made of graphite fiber-reinforced composite (GFRC) and multilayer functionally graded carbon nanotube-reinforced composite (FG-CNTRC) plies. The internal single-walled carbon nanotubes (SWCNTs) are distributed in layer-wise form along the ply thickness direction either uniformly or functionally graded according to four separate patterns. Both the linear and nonlinear of the CNTs distributions form are considered. Theatrical formulations are based on the first-order shear deformation theory (FSDT), and finite element method is employed to obtain the nondimensional natural frequency. The elastic modulus of both GFRC and CNTRC plies composed the hybrid laminated plate is obtained by a micromechanics model. Initially, the provided results are validated by comparing it with the literature; thereafter, a parametric study is carried out the influences of laminates configuration, number of CNTRC plies layers, CNT volume fraction, CNT distribution patterns, linear and nonlinear distribution of CNTs, plate width-to-thickness ratio, plate aspect ratio, boundary conditions, stacking sequences, and number of plies on the free vibration behavior of hybrid laminated plates. Some final remarks considering the laminated plate configuration and the distribution form of the CNT fillers are presented in order to provide a useful observation on the design criteria of the laminated composite plate structures. [ABSTRACT FROM AUTHOR]

In this paper, the free vibration of laminated composited cylindrical shells with two kinds of non-continuous supported boundary condition are investigated. The artificial springs are used to simulate the arcs supported and points supported boundary condition. The equations of motion are derived by using the Chebyshev polynomials and the Lagrange equation, and Donnell's shell theory is employed in this process. The accuracy of the present method compared with that of literature, and convergence analysis is carried out at the same time. Then, the influences of spring stiffness, the number of supported point, and the lamination schemes of non-continuous supported laminated composite cylindrical shells on frequency parameter are studied. The results show that the method can accurately deal with the free vibration of laminated shells with arbitrary non-continuous boundary and arbitrary lamination schemes. [ABSTRACT FROM AUTHOR]

The present paper deals with a new holistic closed-form analytical model for the local buckling load of thin-walled composite beams with I-, Z-, C-, L- and T-cross sections under axial compressive load. The beam is simply supported at both ends (Euler case II), and the plate behaviour of web and flanges is described by the Classical Laminated Plate Theory. Furthermore, symmetric and orthotropic laminates are considered. In previous investigations on composite beams under compression, the web and flange plates are considered as separate composite plates. The present analysis is performed using the Ritz method in which an approach for the entire cross section is realized. The individual webs and flanges of the beam are assembled by suitable continuity conditions into one system. In order to achieve that, new displacement shape functions for web and flange that fulfil all boundary conditions have been developed. The present closed-form analytical method enables the explicit representation of the buckling load for the entire composite beam under axial compression. The comparison between the present approach and comparative finite element simulations shows a very satisfactory agreement. The present method is ideal for pre-designing such structures, highly efficient in terms of computational effort and very suitable for practical engineering work. [ABSTRACT FROM AUTHOR]

The study of vibrational energy harvesting using piezoelectric patch integrated on isotropic beam-like or plate-like thin structures has received significant attention over the past decade. Multilayer orthotropic composite plates are widely used in aerospace, automotive and marine applications, where they can be considered as host structures for vibration-based energy harvesting. In this paper, an exact analytical solution and numerical validation of a piezoelectric energy harvester structurally integrated to a thin multilayer orthotropic plate are presented. Electroelastic model of the thin multilayer composite plate with the piezoelectric patch harvester is developed based on a distributed parameter modeling approach with classical laminate plate theory assumptions for all-four-edge-clamped (CCCC) boundary condition. Closed-form steady-state expressions for coupled electrical outputs and structural vibration response are derived under harmonic transverse force excitation in the presence of a resistive load. Analytical electroelastic FRFs related to the voltage output as well as vibration response to force input are derived and generalized for different boundary conditions of host plate. The results of numerical and analytical models from multiple vibration modes are compared first for validating the analytical model with a case study employing a thin PZT-5A piezoceramic patch attached on the surface of a multilayer orthotropic composite CCCC plate. For this purpose, finite-element analysis is carried out by using ANSYS mechanical APDL software. Then, it is important to specify parameters in energy harvesting model, so positioning of piezoceramic patch harvester and excitation point force on the voltage output FRFs is discussed through an analysis of dynamic strain distribution on the overall plate surface. In addition, the effects of various composite laminate plates with different stacking sequences as host structures on generated power are discussed in details as well. [ABSTRACT FROM AUTHOR]

The plate resting on the elastic foundation is an issue of mutual action between two media. The elastic foundation has important impact on static response of composite plates, while accurate prediction on transverse shear stresses of laminated composite plates resting on elastic foundation and subjected to hygro-thermo-mechanical effects is scare in literature. To fill this gap, this paper proposes a higher-order global-local model (HGLM) satisfying the continuity conditions of transverse shear stresses at interfaces. Based on the model HGLM, analytical solution for the governing differential equations of the simply supported composite plate subjected to mechanical loading, temperature and moisture concentrations is developed by employing Navier's technique followed by the procedure of the separation of variables. Comparing the present results with the available elasticity solutions, it is found that the proposed model HGLM can produce promising transverse shear stresses directly from constitutive equations. Based on the model HGLM, the elastic foundation parameters, stacking sequence and thermal expansion coefficients did have significant effects on the hygro-thermo-elastic response of composite plates. However, the other models lose capacity to simulate the effects of the elastic foundation parameters on displacements and stresses for hygrothermal expansion of composite plates. [ABSTRACT FROM AUTHOR]

The stability behaviour of unsymmetrical laminated structures made of fibre-reinforced plastics is significantly influenced by bending–extension coupling and the comparatively low transverse shear stiffnesses. The aim of this work is to improve the analytical stability analysis of unsymmetrically laminated structures. With the discrete plate theory, the stability of laminated structures can be reduced to single laminated plates. The structure is divided into individual segments, and the surrounding structure is modelled by rotational elastic restraints. The governing equations for single plates under specific boundary conditions can be solved exactly with Lévy-type solutions. In this study, Lévy-type solutions for the mentioned boundary conditions under biaxial compressive load is described for the classical laminated plate theory, the first-order shear deformation theory and the third-order shear deformation theory (TSDT). In addition to transverse shear, bending–extension couplings of unsymmetrical cross-ply and antisymmetrical angle-ply laminates are considered. For the implementation of boundary conditions for the rotational restraints in the context of TSDT, a new set of conditions is formulated. The investigation shows very good agreement of the buckling load with comparative finite element analyses for different layups. [ABSTRACT FROM AUTHOR]

To investigate the dynamic response of circular and ellipse sandwich plates, a higher-order model with five displacement parameters has been proposed, which can fulfill compatible conditions of transverse shear stresses at the interfaces. Based on the proposed model, the finite element formulation has been developed, where the refined-element method is utilized to solve the compatible relation of first derivatives of transverse displacement on the common edges of adjacent elements. By analyzing free vibration of sandwich plates made up of aluminum/composite face sheets and polymethacrylimide core, the performance of the proposed model has been verified. In addition, influence of material properties and geometric parameters on natural frequencies has been also investigated. Results show that displacement modes in the ellipse plate differ from those of the circular plate attributing to different stiffness along x and y directions. Moreover, the ratios of major axis to minor axis have a severe impact on natural frequencies of ellipse sandwich plates. Stiffness of sandwich plates can be explicitly improved by applying the composite face sheets. Furthermore, the relative stiffness of sandwich circular plate can be further improved by changing the lamination configuration, which can demonstrate good designability of sandwich plates with composite face sheets. [ABSTRACT FROM AUTHOR]

Based on three-dimensional theory of elasticity, static bending, free vibration and buckling behaviors of functionally graded carbon nanotube-reinforced composite plates are investigated with the isogeometric analysis (IGA). The carbon nanotubes are supposed to be distributed uniformly and graded functionally along the plate thickness. The refined rule of mixtures is applied to predict the effective material properties. Based on the IGA, the displacement field of the plate is expressed by three-dimensional NURBS basis functions. The Hamilton's principle is used to obtain the formulations for the static bending, free vibration and buckling analysis. The convergence study is performed and the accuracy of the present approach is validated by comparing the numerical results with the published literature. In addition, the effects of CNTs volume fractions, CNTs distributions, geometrical parameters and boundary conditions on the static bending, free vibration and buckling analysis of the functionally graded carbon nanotube-reinforced composite plates are investigated. [ABSTRACT FROM AUTHOR]

This article is concerned with the propagation of guided type-Lamb waves in a magneto-electro-elastic composite plate. As a numerical method, the ordinary differential equation with the Thomson Haskell parameterization of Stroh formalism is employed to determine the wave characteristics in the composite plate by imposing the traction-free boundary condition on the top and bottom surfaces. Multiple crossing appears in the dispersion curves between the symmetric and the antisymmetric Lamb modes, which makes the dispersion curves more complicated and interesting to study. We are trying in this research to find, are these modes really coupled and why? For that, a set of numerical results are presented like the dispersion curves, the non-dimensional frequency, bulk waves slowness curve as well as the mechanical displacement U1 and U3 versus the non-dimensional thickness. These results could be interesting for the analysis and design of new acoustic devices based on magneto-electro-elastic material as well as a good candidate for nondestructive testing technology. [ABSTRACT FROM AUTHOR]

We derive here a fundamental solution for the harmonic vibration of thick asymmetrically laminated composite plates. The kinematics of the plate is based on Reddy's third-order shear deformation theory (J Appl Mech 51:745–752, 1984). The fundamental solution is derived via the Fourier transform, and its final form is given in terms of definite integrals, which are evaluated numerically. All spatial singularities can be obtained explicitly, which makes the fundamental solution suitable for a boundary element method implementation. [ABSTRACT FROM AUTHOR]

The subject of the contribution is an investigation of elastic composite plates with a microperiodic structure along the plate's midsurface. The computational models of the plates are largely based on the homogenization procedures leading to equations with constant coefficients. However, the homogenization theories neglect the microstructure length-scale effect on the plate's dynamic behaviour. The objective of this research is to formulate and investigate a refined theory of the composite plates under consideration, which would describe the microdynamic plate behaviour caused by the microstructure. The possible applications of the proposed theory are shown by an example. [ABSTRACT FROM AUTHOR]

In the present study, a recently developed non-polynomial zigzag theory by the authors is assessed for the buckling analysis of the laminated composite and sandwich plates. This theory assumes a nonlinear distribution for the transverse shear stresses. The model satisfies the transverse shear stress free boundary conditions at top and bottom surfaces of the laminate obviating the need for a shear correction factor. An efficient C0 continuous isoparametric serendipity element is employed for the discretization of plate structure for the assessment of buckling responses. The Gauss quadrature rule with reduced integration scheme for thin laminate and full integration rule for thick laminate are implemented in the analysis. Some representative results are obtained on buckling analysis covering different features of laminated composite and sandwich structures such as modular ratios, aspect ratios, loading conditions, boundary conditions and span to thickness ratios. The evaluated results are compared with results available in the literature to ensure the efficacy of the present theory. The excellent agreement of the evaluated results with the three-dimensional elasticity results concludes that the presented models are not only accurate but also efficient. [ABSTRACT FROM AUTHOR]

This study aims to examine the effect of the diameter, number, and location of the circular cutout on the free vibration response and buckling loads of the laminated composites. Eigen-buckling and free vibrations analyses are performed for the laminated composite plates by using the finite element software ANSYS. Numerical results obtained by the finite element method are compared to the experimental ones. In the numerical analyses, the effect of the delamination around the cutout on the buckling load and the natural frequency is also examined. The critical buckling load and first natural frequency values obtained by both numerical and experimental studies are used to create a prediction model using the artificial neural networks. The Levenberg–Marquardt backpropagation algorithm is used as the training method. It is observed that both the number and location of the cutout affect the critical buckling load and first natural frequency values. Numerical and experimental results are presented together with the ANN prediction results. [ABSTRACT FROM AUTHOR]

We obtain here a new fundamental solution for the harmonic vibration of asymmetric, laminated, anisotropic plates. The fundamental solution is derived via the Fourier transform and its final form is given in terms of definite integrals, which are evaluated numerically. Moreover, we present some of the higher order derivatives of the solution and their explicit spatial singularities, which are necessary for a boundary element method implementation. [ABSTRACT FROM AUTHOR]

A higher-order shear deformation theory is utilized to discuss the vibration of a laminated composite plate containing four magnetostrictive layers based on Pasternak's foundations in the current article. Hamilton's principle is used to derive the governing dynamic equations related to the vibration of present smart structure under velocity feedback control with constant gain distributed. Navier's approach is utilized to give a solution of simply supported laminated composite plates. Effects of all material properties, modes, thickness ratio, aspect ratio, lamination schemes, magnitude of the feedback parameter, the elastic foundations parameters and the thickness, location and number of magnetostrictive layers, on the vibration damping characteristics of the system are investigated and extensively discussed. Findings of the damping coefficients, damped natural frequencies, damping ratio, vibration time and maximum deflection for some different laminates are computed. The influences of studied parameters on the vibration suppression of plates are illustrated graphically. The results indicate increasing of smart layers structures tends to more control of structure and elastic foundations can contribute the stability of the plate significantly. [ABSTRACT FROM AUTHOR]

This article presents the free vibration frequencies of composite plates reinforced with single-walled carbon nanotubes by using a refined simplified two-variable nth-higher-order theory. Four kinds of distribution of uniaxially aligned reinforcement material are presented. The most famous one is the uniform; in addition, three types of functionally graded distributions of carbon nanotubes in the through-thickness direction of the plates are investigated. The effective physical properties of composite media are given according to a refined rule of mixtures approach that contains the efficiency parameters. Exact closed-form formulation based on a refined simplified two-variable nth-higher-order plate theory that can be adapted to the vibration of such plates is investigated. Accuracy of presented approach is validated by comparing its results with those given by other investigators [ABSTRACT FROM AUTHOR]

A novel three-dimensional progressive damage model based on generalized mixed finite element method (GMPDM) was established to investigate the strength and failure behavior of notched composite laminate plate. Firstly, the stress distribution of notched isotropic plate under tension is studied, and the results are compared with the analytical solution to verify the high accuracy of the generalized mixed finite element method. Then, the strength and failure modes of three notched composite laminates are studied. The results are compared with the several groups of results to verify the high-precision of the developed GMPDM method, respectively. [ABSTRACT FROM AUTHOR]

A steady-state thermomechanical analysis model is established for the composite laminated plate with transverse cracks and delaminations based on the extended layerwise method. The one-dimensional weak and strong discontinuous functions are employed to simulate the interlaminar interfaces and the delaminations, respectively, while the transverse crack is simulated in the in-plane displacement fields by using the standard extended finite element method. The temperature field in the thickness direction is obtained by using a one-dimensional steady-state heat conduction equation and constructed with the linear Lagrange interpolation functions in the thickness direction. In several numerical examples, the proposed model is verified for the laminated plates with/without transverse crack and/or delaminations against the classic laminated plate theory, first-order shear deformation theory, Reddy's layerwise theory or three-dimensional elastic model. [ABSTRACT FROM AUTHOR]

Although considerable attention has been devoted to the experimental research works of plant fiber-reinforced composites, theoretical determination of their structural characteristics is also much needed one in their evolution. But it is still considered as a difficult process due to the several factors such as short and discontinuous fiber form, plant fiber's intrinsic characteristics, fiber anisotropy and porosity. In this study, vibration characteristics of woven jute/epoxy and woven aloe/epoxy laminated composite plate structures are investigated theoretically and experimentally. The elastic constants of the woven jute/epoxy and woven aloe/epoxy laminated composites are obtained through experimental testing. The governing differential equations of motion for the uniform woven jute/epoxy and woven aloe/epoxy laminated thick composite plates are carried out using the p-version finite element method based on higher-order shear deformation theory. The effectiveness of the developed finite element formulations is demonstrated by comparing the natural frequencies obtained using the present finite element method with those obtained from the experimental measurements. Also a comparative study is carried out between the results of h-version FEM and p-version FEM to check their accuracies and efficiencies. The effects of aspect ratio and angle of fiber orientation under various end conditions on the free vibration responses of the woven jute/epoxy laminated composite plate are also investigated. The forced vibration response of the woven jute/epoxy laminated composite plate under the harmonic force excitation is carried out under various end conditions. [ABSTRACT FROM AUTHOR]

An enhanced efficient zigzag theory is presented for the static response in elastic composite plates under mechanical loading. The number of variables is six, which is one more than the conventional zigzag theory. Transverse shear stresses have been obtained through the use of constitutive equations in both symmetric and antisymmetric laminates under uniformly and sinusoidally applied mechanical load. The theory has a good representation of all the three displacement components. This is obtained by using individual descriptions for each layer as is observed in three-dimensional elasticity solution. Interlaminar continuity conditions on all displacement components, all transverse stresses and on the gradient of transverse normal stress as well as transverse shear-free conditions on the top and the bottom surfaces have been utilized to make the primary variables independent of number of layers in the laminate. Equilibrium equations and boundary conditions are derived from variational principle. Navier solution is obtained for simply supported square and rectangular plates. The accuracy of the present theory is assessed by comparison with three-dimensional (3D) elasticity solution. It is found that refinement of the transverse displacement alone is not sufficient to make the new theory capable of providing good accuracy in calculation of transverse stresses from constitutive equations, though some improvement is obtained in case of symmetric laminates. [ABSTRACT FROM AUTHOR]

Based on the shear spring model, the propagation of Love wave in two-layered piezoelectric/elastic composite plates under the influence of interfacial defect is investigated. The piezoelectric layer is electrically shorted at both top and bottom surfaces. The wave form solutions of the piezoelectric and elastic layers are obtained, and the dispersion equation is derived by subjecting the boundary conditions and the continuity conditions to the obtained wave form solutions. Numerical results are performed for PZT4/aluminum composite plate. The phase velocities and the mode shapes of mechanical displacement and electric potential are illustrated graphically. The results show that both the interfacial defect and the thickness ratio between the piezoelectric and elastic layers have significant effect on the propagation characteristics of Love wave. One important feature is observed that the interfacial defect always decreases the phase velocities. [ABSTRACT FROM AUTHOR]