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• Exact solutions for the material length scale effect on the static responses of flexoelectric nanobeam are derived. • Optimum values of the length parameter are determined for both active and passive beam. • These solutions suggest that the flexoelectric nanobeam may be exploited for developing smart nanosensor and nanoactuator. This paper is concerned with the derivation of the exact solutions for investigating the effect of material length scale on the static responses of the simply supported flexoelectric nanobeams considering a couple stress theory. The material length scale parameter estimates the coefficient linearly relating the rotational strain gradient to the couple stress in terms of the shear modulus of the beam material. Exact solutions for the displacements, stresses, electric displacements and the electric potential are derived while the beam is under closed circuit and open circuit conditions. Optimum value of the length parameter below which the response of the beam becomes independent of the couple stress effect has been determined while the beam acts as an actuator. The effect of this length parameter on the performance of the beam as an energy harvester has also been investigated for finding the optimum value of this length parameter. The benchmark results presented here may be useful for verifying further research and suggests that the flexoelectric nanobeams may be effectively exploited for developing advanced smart nanosensors and nanoactuators. [ABSTRACT FROM AUTHOR]

Static analysis of doubly curved laminated composite shells with rectangular plan form has been carried out using a novel hybrid Trefftz finite element (HTFE) model. A typical higher order shear deformation theory (HSDT) has been used for describing the kinematics of deformations delineating both internal and auxiliary displacement fields. This HSDT allows to derive the system of governing partial differential equations of the single layer equivalent to the element domain. The characteristic functions forming the exact solutions of these homogenous governing equilibrium equations are used as the Trefftz functions. A key aspect of our HTFE strategy is its efficiency in bypassing the use of particular solution of the governing equations. Validation against the exact solutions reveals the precision of this novel HTFE model. The versatility of the Trefftz functions allows them to accommodate a spectrum of geometric configurations, ranging from standard to complex polygonal HTFE designs. The HTFE model for the doubly curved composite shells employing the HSDT marks a significant advancement in the analysis of doubly curved spherical, paraboloid and hyperboloid cross-ply and antisymmetric angle-ply shells. [ABSTRACT FROM AUTHOR]

In this paper, performance of the smart constrained layer damping (SCLD) treatment with elliptical geometrical plan form is investigated for controlling the vibrations of various types of doubly curved composite shells. The SCLD treatment is composed of a viscoelastic layer and an advanced constraining piezoelectric composite (PZC) layer attached at the top surface of the composite shell. A mesh free (MF) model of the smart composite shell has been developed based on the element free Galerkin approach to study its dynamic behaviour within the framework of a mixed layerwise displacement field theory considering transverse extensibility. Spherical, paraboloid and hyperboloid type composite shells with antisymmetric/symmetric cross-ply as well as general angle-ply lamination sequences are considered for the analysis. The numerical results demonstrated that the elliptical SCLD patches are more efficient in attenuating the vibration of the spherical and paraboloid laminated shells while the regular rectangular/square plan form patches are effective for the hyperboloid shells. The numerical results also indicate that the elliptical patches are having higher performance index in enhancing the active damping characteristics of the composite shells. Investigations are also carried out to analyze the effect of the variation in orientation of the piezoelectric fibers in the active PZC layers in attenuating the vibration of shells. • Smart constrained layer damping (SCLD) of laminated composite shells has been investigated. • Elliptical patches of active constrained layer damping treatment has been used. • A three-dimensioanl element free Galerkin (EFG) model has been developed for the first time for such analyses. • It is shown that the control authority of the elliptical patch is better than the square type patches. [ABSTRACT FROM AUTHOR]

Abstract In this article, performance of the elliptical patches of smart constrained layer damping (SCLD) treatment is investigated for controlling vibrations of smart laminated composite plates. A three dimensional mesh free model (MFM) has been implemented for the first time based on the element free Galerkin (EFG) method and layer wise displacement theory for studying the dynamic behavior of the composite plates integrated with the SCLD treatments. Symmetric/antisymmetric cross-ply and general angle-ply laminates are considered for the substrate of the smart composite plates. Circular and regular rectangular type patches are also considered for the analysis. It is observed that the elliptical SCLD patches are more efficient in attenuating the amplitude of vibration in the laminated composite plates as compared to the circular and square type patches. The results from numerical analysis also reveal that the elliptical patches have the maximum performance index followed by the circular and the square type SCLD patches in enhancing the active damping characteristics of smart composite plates. The performance of the elliptical patch is sensitive to the piezoelectric fiber orientation angle and becomes maximum if the piezoelectric fiber orientation is vertical irrespective of the types of SCLD patches considered as well as the lamination sequence. [ABSTRACT FROM AUTHOR]

Abstract This paper deals with the derivation of the exact solutions for the static electro-mechanical response of a simply-supported doubly curved (DC) smart shell, composed of a piezoelectric fiber reinforced composite (PFRC) placed over a laminated substrate. These responses are evaluated when the system is subjected to distributed electrical and mechanical loads. The electro-mechanical governing equations and the associated boundary conditions have been derived here for the curvilinear coordinate system using the variational principle. Closed-form expressions for the mechanical displacement and the electrical potential have been obtained by solving these governing differential equations and simultaneously satisfying the derived boundary conditions. Numerical results have been presented for different shell geometries. The effect of the curvature and the geometric parameters of the PFRC layer over its performance as an actuator are studied and compared for these shells. Also, the effect of varying geometric parameters of the PFRC over its performance as a sensor is studied. Optimal dimensions of the PFRC for use as an actuator and sensor/harvester have been proposed. This study may be considered as a benchmark for use in the numerical and experimental studies involving smart shells. Highlights • Exact solutions for the governing equations modelling the electro-mechanical response of smart shells have been derived. • Electrical and mechanical governing equations have been solved without any assumptions over the displacement fields. • Effect of curvature over the performance of piezoelectric layer as an actuator and sensor/harvester has been studied. • Effect of size of the piezoelectric layer on its performance has been investigated. • This paper serves as a benchmark for verifying numerical and experimental models. [ABSTRACT FROM AUTHOR]

Abstract In this paper, exact solutions for the static bending response of laminated composite beams have been derived considering the effect of strain gradient elasticity. Separate solutions for the laminate comprising of isotropic and orthotropic laminae have been presented here. The sixth-order tensor for the higher order elastic coefficients has been evaluated using the generalized first strain gradient elasticity model with three independent material length constants. The significance of the gradient elasticity in low-dimensional structures has been established employing numerical examples of micro and nano-beams, and comparing the current results with the classical elasticity results. A parametric study over the variation of the axial, transverse Cauchy and physical stresses across the thickness of the beam has been conducted. Also, the discontinuity of the inter-laminar transverse Cauchy stresses and higher order stresses across the thickness has been studied in the current framework. The exact solutions developed in this paper may be used as benchmark results for validating further research involving the strain gradient elastic response of low-dimensional laminated composite beams. [ABSTRACT FROM AUTHOR]

Geometrically nonlinear vibration control of fiber reinforced magneto-electro-elastic or multiferroic fibrous composite plates using active constrained layer damping treatment has been investigated. The piezoelectric (BaTiO 3 ) fibers are embedded in the magnetostrictive (CoFe 2 O 4 ) matrix forming magneto-electro-elastic or multiferroic smart composite. A three-dimensional finite element model of such fiber reinforced magneto-electro-elastic plates integrated with the active constrained layer damping patches is developed. Influence of electro-elastic, magneto-elastic and electromagnetic coupled fields on the vibration has been studied. The Golla–Hughes–McTavish method in time domain is employed for modeling a constrained viscoelastic layer of the active constrained layer damping treatment. The von Kármán type nonlinear strain-displacement relations are incorporated for developing a three-dimensional finite element model. Effect of fiber volume fraction, fiber orientation and boundary conditions on the control of geometrically nonlinear vibration of the fiber reinforced magneto-electro-elastic plates is investigated. The performance of the active constrained layer damping treatment due to the variation of piezoelectric fiber orientation angle in the 1–3 Piezoelectric constraining layer of the active constrained layer damping treatment has also been emphasized. [ABSTRACT FROM AUTHOR]

This paper is concerned with the smart constrained layer damping (SCLD) treatment of laminated composite shells with variable thickness undergoing geometrically nonlinear vibrations. Three dimensional fractional derivative model (FDM) has been implemented for modelling the constrained viscoelastic layer of the SCLD treatment. The constraining layer of the SCLD treatment is made of vertically/obliquely reinforced 1–3 piezoelectric composites (PZCs) and acts as the distributed actuator. The strain-displacement relations are based on the simplified Novozhilov nonlinear shell theory to introduce the geometric nonlinearity in the large amplitude vibrations of the variable thickness shells. A three dimensional smart nonlinear finite element (FE) model has been developed for carrying out this analysis. Several numerical results are presented to check the accuracy of the present three-dimensional FDM for analyzing the passive and active control authority of the SCLD patch. Also the efficacy of the activated SCLD patch in controlling geometrically nonlinear vibration is computed for variable thickness shells and compared with shells of constant thickness. [ABSTRACT FROM AUTHOR]

This paper is concerned with the development of a mesh free model for the static analysis of smart nanobeams. The top surface of the substrate nanobeam is integrated with a flexoelectric layer which acts as the distributed actuator of the nanobeam. A layer wise displacement theory has been used to derive the model. Both thick and thin substrate nanobeams are considered for presenting the numerical results. The responses of the smart nanobeams computed by the present new mesh free model based on the layer wise displacement theory excellently match with those obtained by the exact solutions. The performance of the active flexoelectric layer either as an axial or as a shear actuator has been investigated. Variation of the control authority of the active flexoelectric layer with its thickness has also been investigated. The model derived here suggests that the mesh free method can be efficiently used for the numerical analysis of smart nanostructures coupled with flexoelectric actuator layer. [ABSTRACT FROM AUTHOR]

This paper deals with the finite element analysis of active constrained layer damping (ACLD) of laminated composite plates using fractional order derivative constitutive relations for viscoelastic material. The constraining layer of the ACLD treatment is composed of the vertically/obliquely reinforced 1–3 piezoelectric composites (PZCs). The novelty of the present analysis is that the three dimensional fractional derivative model (FDM) of the constrained viscoelastic layer has been derived in time domain. A three-dimensional finite element model has been developed based on the FDM of the viscoelastic layer. Thin laminated plates with various boundary conditions and stacking sequences are emphatically analyzed to investigate the effectiveness of the three-dimensional FDM for both the passive and active control authority of the ACLD patch. [ABSTRACT FROM AUTHOR]

This article deals with the analysis of active damping of geometrically nonlinear vibrations of functionally graded magneto-electro-elastic (FGMEE) plates integrated with the patches of the active constrained layer damping (ACLD) treatment. The constraining layer of the ACLD treatment is composed of the vertically/obliquely reinforced 1–3 piezoelectric composite (PZC). The constrained viscoelastic layer of the ACLD treatment is modeled by using a Golla–Hughes–McTavish (GHM) method in time domain. The material properties of the FGMEE plate are assumed to be functionally graded along the thickness direction according to a simple power-law distribution. Based on the layer-wise shear deformation theory, a three-dimensional finite element (FE) model of the overall smart FGMEE plate has been developed taking into account the effects of coupling between elasticity, electric and magnetic fields, while the von Kármán type nonlinear strain displacement relations are used for incorporating the geometric nonlinearity. Influence of the variation of the power law index, material gradation, edge boundary conditions and the piezoelectric fiber orientation angle in the 1–3 PZC constraining layer of the ACLD treatment on the control of geometrically nonlinear vibrations of the FGMEE plates have been investigated. [ABSTRACT FROM AUTHOR]

A novel continuous unidirectional piezoelectric fuzzy fiber reinforced composite (PFFRC) comprised of zig-zag single-walled carbon nanotubes and piezoelectric fibers as reinforcements embedded in a conventional polymer matrix has been studied. Effective piezoelectric and elastic properties of this composite have been determined by the method of cell (MOC) approach and the Mori–Tanaka (MT) method. It is found that the effective in-plane piezoelectric coefficient and elastic coefficients of the PFFRC are significantly improved over those of the existing 1–3 piezoelectric composite without reinforced with carbon nanotubes. [ABSTRACT FROM AUTHOR]

This paper deals with the active vibration control of thin rotating laminated composite truncated conical shells using vertically and obliquely reinforced 1-3 piezoelectric composite (PZC) materials as the constraining layer of an active constrained layer damping (ACLD) treatment. A finite element model has been derived to formulate the dynamics of the rotating thin laminated truncated conical shells integrated with the patches of ACLD treatment. Hamilton′s principle has been used to derive the equations of motion of rotating shell integrated with patches. The finite element model includes the effects of the Coriolis, Centrifugal acceleration, and the initial hoop tension caused due to rotation. The effectiveness of these patches for the vibration attenuation of thin rotating symmetric/antisymmetric cross-ply and antisymmetric angle-ply laminated truncated conical shell has been examined. Both in-plane and out-of-plane actuations of the constraining layer of the ACLD treatment has been utilized. The effects of variation of the semi-cone angle and the rotational speed of the shell on the performance of these patches have been investigated. Particular emphasis has been placed on ascertaining the performance of patches when the orientation angle of the piezoelectric fibers in the constraining layer is varied in two mutually orthogonal vertical planes. It is found that the maximum performance of patches is obtained for the piezoelectric fiber orientation angle of 0° and the vertically and obliquely reinforced 1-3 PZCs have great potential for controlling the vibration of rotating shells. [ABSTRACT FROM AUTHOR]

This paper presents the exact solutions for the plate type piezoelectric bimorph energy harvesters composed of laminated cross-ply or angle-ply substrate plate. Both series and parallel connections of the piezoelectric layers of the bimorphs are considered for deriving the exact solutions. Since the exact solutions for the layers of the laminated substrate plate are available in the open literature exact solutions for the piezoelectric layers are only derived here for finding the exact solutions of the harvesters. The piezoelectric layers should be orthotropic or generally orthotropic for deriving the exact solutions. Three sets of exact solutions for the piezoelectric layers are required to be derived. The electric potential induced by the bimorph in which the piezoelectric layers are connected in series is significantly larger than that in case of the bimorph with piezoelectric layers connected in parallel. The effects of the variations of the off-axis angle in the generally orthotropic piezoelectric layer, the length over width ratio of the harvester and the thickness of the piezoelectric layers on the induced electric potential have been studied. The expressions for the exact solutions can be used in a straight forward manner for verifying the experimental and the numerical results. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the active constrained layer damping (ACLD) of large amplitude vibrations of smart magneto-electro-elastic (MEE) plates. The constraining layer of the ACLD treatment is composed of the vertically/obliquely reinforced 1–3 piezoelectric composite (PZC). The constrained viscoelastic layer of the ACLD treatment is modeled by using Golla–Hughes–McTavish (GHM) method in time domain. A three-dimensional finite element model of the overall smart MEE plates has been developed taking into account the electro-elastic and magneto-elastic coupling effects. The von Kármán type nonlinear strain displacement relations have been used for modeling such coupled MEE problems. Particular attention has been paid to investigate the performance of the ACLD treatment due to the variation of the piezoelectric fiber orientation angle. [ABSTRACT FROM AUTHOR]

Abstract: A novel three-phase shear lag model is derived to study the load transfer characteristics of the short fuzzy fiber reinforced composite (SFFRC) subjected to the thermomechanical loading. The distinctive feature of the SFFRC is that the short carbon fiber reinforcements coated with radially aligned carbon nanotubes (CNTs) are uniformly interlaced in the polymer matrix. The main novelty of the shear lag model derived in this study is that the interactions between the representative volume elements (RVEs) of the SFFRC, the application of the radial and the thermal loads on the RVE, and the radial as well as the axial deformations of different orthotropic constituent phases of the SFFRC have been taken into account. Particular emphasis has been placed on investigating the effect of waviness of CNTs on the load transfer characteristics of the SFFRC when the wavy CNTs are coplanar with either of the two mutually orthogonal planes. In the absence and the presence of the applied radial and thermal loads on the RVE, the shear lag analysis revealed that if the wavy CNTs are coplanar with the axial plane of the carbon fiber such that the amplitudes of the CNTs are parallel to the length of the carbon fiber then the load transfer characteristics of the SFFRC are significantly improved over those of the composite with and without the straight CNTs. The limiting value of the effective aspect ratio of the carbon fiber is also found for the efficient load transfer to the carbon fiber. [Copyright &y& Elsevier]

Abstract: This paper deals with the investigation of the effect of carbon nanotube (CNT) waviness on the effective coefficient of thermal expansion (CTE) of a novel continuous fuzzy fiber reinforced composite (FFRC). This novel FFRC is composed of carbon fibers, sinusoidally wavy CNTs and epoxy matrix. The sinusoidally wavy CNTs are radially grown on the circumferential surfaces of the carbon fibers. Analytical micromechanics model based on the method of cells (MOC) approach is derived to investigate the influence of the waviness of CNTs on the effective CTEs of the FFRC. The present study reveals that if the amplitudes of the radially grown sinusoidally wavy CNTs are parallel to the axis of the carbon fiber then the thermoelastic properties of the FFRC are significantly improved over those of the FFRC being composed of straight CNTs. [Copyright &y& Elsevier]

Abstract: The effective thermal conductivities of a novel fuzzy fiber reinforced composite (FFRC) have been determined by employing the effective medium approach in conjunction with the composite cylinder assemblage approach. The novel constructional feature of this FFRC is that the uniformly spaced carbon nanotubes (CNTs) are radially grown on the circumferential surfaces of the unidirectional carbon fiber reinforcements. The present study reveals that the transverse thermal conductivities of the FFRC are improved up to ∼1040% and ∼400% over those of the composite without CNTs when the values of CNT volume factions present in the FFRC are 6.88% and 4.27%, respectively. It is also found that the CNT/polymer matrix interfacial thermal resistance does affect the effective thermal conductivities of the FFRC, and the effective values of thermal conductivities of the FFRC are improved with the increase in the values of carbon fiber volume fraction and temperature. [Copyright &y& Elsevier]

Abstract: This work deals with the transient hydroelastic analysis of a sandwich beam which represents a boat hull. The beam is subjected to slamming pressure while it enters into water with constant vertically downward velocity. A coupled hydroelastic finite element model is developed using higher order shear and normal deformation theories for the faces and the core of the beam and the velocity potential theory for the fluid. Transient responses of the beam for transverse deflection and stresses are studied. Dynamic failure analysis has been carried out to investigate the initiation and cause of the failure of the beam due to slamming load. [Copyright &y& Elsevier]

Abstract: This paper deals with the analysis of active damping of geometrically nonlinear vibrations of doubly curved smart sandwich shells integrated with a patch of active constrained layer damping (ACLD) treatment. The substrate sandwich shell is composed of orthotropic laminated composite faces separated by a thick flexible core. The constraining layer of the ACLD treatment is made of the vertically/obliquely reinforced 1–3 piezoelectric composites (PZCs). The constrained viscoelastic layer is modeled using the Golla–Hughes–McTavish (GHM) method in the time domain. A three dimensional finite element (FE) model has been developed to study this coupled nonlinear electro-elastic problem. The numerical results indicate that the ACLD patch significantly improves the damping characteristics of the paraboloid and hyperboloid sandwich shells with laminated cross-ply and angle-ply facings for suppressing their geometrically nonlinear vibrations. Particular emphasis has been placed on investigating the effect of the variation of piezoelectric fiber orientation angle on the performance of the ACLD treatment. Unlike the doubly curved laminated composite shells, the performance of the ACLD treatment becomes maximum for causing active damping of geometrically nonlinear vibrations of doubly curved sandwich shells with laminated composite facings if the constraining layer of the treatment is made of obliquely reinforced 1–3 PZC. [Copyright &y& Elsevier]

We present the finite element (FE) model using the first-order shear deformation theory (FSDT) to investigate the damping performance of laminated hybrid fiber-reinforced composite (HFRC) smart plates via the active constrained layer damping (ACLD) treatment. A unique feature of the HFRC is that the nanoscale carbon nanotubes (CNTs) are embedded in the matrix phase of carbon fiber composite to improve the overall properties, especially the damping characteristics of the resulting HFRC. Two- and three-phase micromechanical models are employed to determine the effective elastic properties of the base composite and HFRC respectively. The constraining layer of the ACLD treatment is considered to be made of vertically reinforced 1–3 piezoelectric composite (PZC) material. The system consists of a laminated HFRC plate integrated with the two patches of ACLD treatment and the numerical results are computed for three cases: symmetric and anti-symmetric cross-ply, and anti-symmetric angle-ply. The damping performance of the laminated HFRC square plate is significantly enhanced over the laminated base composite plate due to the incorporation of a small amount of CNTs. In particular, the anti-symmetric angle-ply case provides better damping than symmetric/anti-symmetric cross-ply cases. Analysis of the HFRC plate showed that its vibration amplitudes can be attenuated from ∼ 8 to ∼ 16% by adding a small amount CNTs. The effect of in-plane and transverse actuation of 1–3 PZC on the damping characteristics of the overall plate was also studied. We found that the transverse actuation significantly influences the damping performance of the overall plate. The outcomes of our study provide substantial evidence that the addition of a small amount of CNTs in the conventional composite structure can improve its damping performance significantly. This is practically possible in view of the recent research activities in the field of fabrication of large-scale CNT-based hybrid composite structures. • FE model is developed to study the damping performance of laminated CNT-based hybrid composite plates. • Micromechanical models are developed to determine the effective elastic properties of hybrid composites. • Damping performance of laminated HFRC plate is significantly enhanced due to the incorporation of small amount of CNTs. • Transverse actuation significantly influences the damping performance of overall plate. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the performance of the active constrained layer damping (ACLD) treatment for active control of thin laminated cylindrical shells conveying fluid has been investigated. The constraining layer of the ACLD treatment has been considered to be made of vertically or obliquely reinforced 1–3 piezoelectric composite (PZC) materials. A three-dimensional finite element model has been developed for the laminated shells integrated with the patches of ACLD treatment to describe the coupled hydroelastic behavior of the shells. Velocity feedback control law has been implemented to activate the patches. Symmetric and antisymmetric cross-ply and antisymmetric angle-ply shells have been considered for evaluating the numerical results. Emphasis has also been placed on investigating the effect of the variation of the piezoelectric fiber orientation angle in the PZC constraining layer on the performance of the patches. [Copyright &y& Elsevier]

Abstract: The effective properties of a continuous fuzzy fiber-reinforced composite have been determined by employing the method of cells approach and the finite element (FE) method. The novel constructional feature of this fuzzy fiber-reinforced composite is that the uniformly aligned carbon nanotubes (CNTs) are radially grown on the surface of the horizontal carbon fibers. The effective properties of this fuzzy fiber-reinforced composite are estimated with and without the consideration of an interphase formed due to non-boned interaction between a CNT and the polymer matrix. Effective elastic properties of the fuzzy fiber-reinforced composite estimated by the method of cells approach have been compared with those predicted by the FE method. It has been found that the transverse effective properties of this composite are significantly improved due to the radial growing of CNTs on the surface of the carbon fiber. It is also found that the consideration of the CNT/matrix interphase has a negligible effect on the effective elastic properties of the fuzzy fiber-reinforced composite. [Copyright &y& Elsevier]

Abstract: A novel short fuzzy fiber-reinforced composite reinforced with aligned short carbon fibers and carbon nanotubes (CNTs) has been analyzed in this study. The constructional feature of this composite is that the uniformly aligned CNTs are radially grown on the circumferential surfaces of short carbon fibers. Micromechanical model based on the Mori–Tanaka method is derived to estimate the effective elastic properties of the short fuzzy fiber-reinforced composite. Effective elastic properties of the short fuzzy fiber-reinforced composite estimated by the Mori–Tanaka method have been compared with those predicted by the finite element (FE) method. The effective properties of the short fuzzy fiber-reinforced composite are estimated in the presence and the absence of an interphase between a CNT and the polymer matrix formed due to non-bonded van der Waals interaction between them. It has been found that the transverse effective properties of this composite are significantly improved due to the radial growing of CNTs on the circumferential surface of the short carbon fibers and the CNT/ polymer matrix interphase has negligible effect on the effective properties of the short fuzzy fiber-reinforced composite. Effects of the different types of zig–zag CNTs and the variation of their volume fraction on the effective properties of the short fuzzy fiber-reinforced composite are also investigated. [Copyright &y& Elsevier]

Abstract: This paper deals with the analysis of active control of vibration of thin laminated composite truncated circular conical shells using vertically and obliquely reinforced 1-3 piezoelectric composite (PZC) materials as the constraining layer of the active constrained layer damping (ACLD) treatment. A finite element model of smart truncated conical laminated shells integrated with the patches of such ACLD treatment has been developed to demonstrate the performance of these patches on enhancing the damping characteristics of thin symmetric and antisymmetric cross-ply and antisymmetric angle-ply laminated truncated conical shells. Velocity feedback control loop has been implemented to activate the patches. The effect of variation of semi-cone angle on the performance of the patches for controlling first few modes of the truncated conical laminated shells has been demonstrated. Emphasis has also been placed on exploring the effect of variation of piezoelectric fiber orientation angle in the constraining layer on the control authority of the ACLD patches. [Copyright &y& Elsevier]

Abstract: This paper deals with the analysis of active constrained layer damping (ACLD) of geometrically nonlinear transient vibrations of doubly curved laminated composite shells. Vertically/obliquely reinforced 1–3 piezoelectric composite (PZC) and active fiber composite (AFC) materials are used as the materials of the constraining layer of theACLD treatment. The Golla–Hughes–McTavish (GHM) method has been implemented to model the constrained viscoelastic layer of the ACLD treatment in time domain. The first-order shear deformation theory (FSDT) and the Von Kármán type non-linear strain displacement relations are used for analyzing this coupled electro-elastic problem. A three dimensional finite element (FE) model of doubly curved laminated smart composite shells integrated with ACLD patches has been developed to investigate the performance of these patches for controlling the geometrically nonlinear transient vibrations of the shells. The numerical results indicate that the ACLD patches significantly improve the damping characteristics of the doubly curved laminated cross-ply and angle-ply shells for suppressing their geometrically nonlinear transient vibrations. It is found that the performance of the ACLD patch with its constraining layer being made of the AFC is significantly higher than that of the ACLD patch with vertically/obliquely reinforced 1–3 PZC constraining layer. The effects of variation of piezoelectric fiber orientation in both the obliquely reinforced 1–3 PZC and the AFC constraining layers on the control authority of the ACLD patches have also been investigated. [Copyright &y& Elsevier]

Abstract: This paper deals with the geometrically nonlinear dynamic analysis of functionally graded (FG) laminated composite plates integrated with a patch of active constrained layer damping (ACLD) treatment. The constraining layer of the ACLD treatment is considered to be made of the piezoelectric fiber reinforced composite (PFRC) material. Each layer of the substrate FG laminated composite plate is made of fiber-reinforced composite material in which the fibers are longitudinally aligned in the plane parallel to the top or bottom surface of the layer and the layer is assumed to be graded in the thickness direction by way of varying the fiber orientation angle across its thickness according to a power-law. The novelty of the present work is that, unlike the traditional laminated composite plates, the FG laminated composite plates are constructed in such a way that the continuous variation of material properties and stresses across the thickness of the plates is achieved. The constrained viscoelastic layer of the ACLD treatment is modeled using the Golla–Hughes–McTavish (GHM) method. Based on the first-order shear deformation (FSDT) theory, a finite element model has been developed to model the open-loop and closed-loop nonlinear dynamics of the overall FG laminated composite plates. Both symmetric and asymmetric FG laminated composite plates are considered as the substrate plates for presenting the numerical results. The analysis suggests the potential use of the ACLD treatment with its constraining layer made of the PFRC material for active control of geometrically nonlinear forced vibrations of FG laminated composite plates. The effect of piezoelectric fiber orientation in the active constraining PFRC layer on the damping characteristics of the overall FG plates is also investigated. [Copyright &y& Elsevier]

Abstract: This paper addresses the analysis of active constrained layer damping (ACLD) of geometrically nonlinear transient vibrations of laminated thin composite plates using piezoelectric fiber-reinforced composite (PFRC) materials. The constraining layer of the ACLD treatment is considered to be made of the PFRC materials. The Golla–Hughes–McTavish (GHM) method has been used to model the constrained viscoelastic layer of the ACLD treatment in the time domain. A finite element model has been developed for the cross-ply and antisymmetric angle-ply plates integrated with the patches of ACLD treatment undergoing geometrically nonlinear vibrations. The Von Ka`rma`n-type nonlinear strain displacement relations and the first-order shear deformation theory (FSDT) are used for deriving this coupled electromechanical nonlinear finite element model. The numerical results indicate that the ACLD patches significantly improve the damping characteristics of the cross-ply and antisymmetric angle-ply plates for suppressing the geometrically nonlinear transient vibrations of the plates. Emphasis has also been placed on investigating the effect of variation of fiber orientation in the PFRC material on the control authority of the ACLD patches. [Copyright &y& Elsevier]

Abstract: This paper deals with the analysis of active constrained layer damping (ACLD) of laminated cylindrical composite shells using vertically and obliquely reinforced 1–3 piezoelectric composite materials as the material of the constraining layer of the ACLD treatment. A finite element model has been developed for analyzing the ACLD of laminated symmetric and antisymmetric cross-ply and angle-ply composite shells integrated with the patches of such ACLD treatment. Both in-plane and out-of-plane actuation of the constraining layer of the ACLD treatment has been utilized for deriving the finite element model. The analysis revealed that the vertical actuation dominates over the in-plane actuation. Particular emphasis has been placed on investigating the performance of the patches when the orientation angle of the piezoelectric fibers of the constraining layer is varied in the two mutually orthogonal vertical planes. The analysis revealed that the vertically reinforced 1–3 piezoelectric composites which are in general being used for the distributed sensors can be potentially used for the distributed actuators of high-performance light-weight smart cylindrical shells. [Copyright &y& Elsevier]

Abstract: In this paper, a nonlinear static finite element analysis of simply supported smart functionally graded (FG) plates in the presence/absence of the thermal environment has been presented. The substrate FG plate is integrated with the patches of piezoelectric fiber reinforced composite (PFRC) material which act as the distributed actuators of the plate. The material properties of the FG substrate plate are assumed to be temperature dependent and graded along the thickness direction according to a simple power-law distribution in terms of the volume fractions of the constituents. The derivation of this nonlinear thermo-electro-mechanical coupled finite element model is based on the first order shear deformation theory and the Von Karman type geometric nonlinearity. The numerical solutions of the nonlinear equations of the finite element model are obtained by employing the direct iteration method. The numerical illustrations suggest the potential use of the distributed actuator made of the PFRC material for active control of nonlinear deformations of smart FG structures. The effects of volume fraction index of the FG material of the substrate plates and the locations of the PFRC patches on the control authority of the patches are investigated. Emphasis has also been placed on investigating the effect of variation of piezoelectric fiber orientation angle in the PFRC patches on their actuation capability for counteracting the large deflections of FG plates. [Copyright &y& Elsevier]

This paper is concerned with the static analysis of simply supported cross-ply substrate plates integrated with a layer of piezoelectric fiber reinforced composite material undergoing nonlinear deformations. The von Kármán type nonlinear strain displacement relations and first order shear deformation theory are used to formulate the variational model of this electromechanical coupled problem. Subsequently, Galerkin procedure is employed to derive the nonlinear algebraic governing equations which are solved by usingNewton-Raphson method. The results suggest the potential use of PFRC material for distributed control of nonlinear deformations of smart composite structures. The effect of variation of piezoelectric fiber orientation on the actuating capability of the PFRC actuator for counteracting the nonlinear deformations of the smart composite plates has also been investigated. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the performance of active constrained layer damping (ACLD) treatment for active structural–acoustic control of a vibrating thin laminated cylindrical panel has been investigated. The constraining layer of the ACLD treatment has been considered to be made of piezoelectric fiber-reinforced composite (PFRC) material. A finite element model has been developed for the laminated panels integrated with the patches of ACLD treatment to describe the coupled structural–acoustic behavior of the panels enclosing an acoustic cavity. Both velocity and pressure rate feedback controls have been implemented to activate the patches. Symmetric and antisymmetric cross-ply and antisymmetric angle-ply panels have been considered for evaluating the numerical results. Emphasis has also been placed on investigating the effect of the piezoelectric fiber orientation in the PFRC layer and the shallowness angle of the cylindrical panels on the performance of the patches. [Copyright &y& Elsevier]

This paper deals with the analysis of vertically reinforced 1-3 piezoelectric composite materials as the material for the distributed actuator of smart laminated composite plates. A simple micromechanics model has been derived to predict the effective elastic and piezoelectric coefficients of these piezoelectric composites which are useful for the three dimensional analysis of smart structures. The main concern of this study is to investigate the performance of a layer of this vertically reinforced 1-3 piezoelectric composite material as the constraining layer of the active constrained layer damping (ACLD) treatment. A finite element model has been developed for analyzing the active constrained layer damping of laminated symmetric and antisymmetric cross-ply and angle-ply composite plates integrated with the patches of such ACLD treatment. Both in-plane and out-of-plane actuation of the constraining layer of the ACLD treatment have been utilized for deriving the finite element model. The analysis revealed that the vertical actuation dominates over the in-plane actuation. Particular emphasis has been placed on investigating the performance of the patches when the orientation angle of the piezoelectric fibers of the constraining layer is varied in the two mutually orthogonal vertical planes. Also, the effect of different boundary conditions on the performance of the patches has been studied. The analysis revealed that the vertically reinforced 1-3 piezoelectric composites which are in general being used for the distributed sensors can be potentially used for the distributed actuators of high performance light-weight smart structures. [ABSTRACT FROM AUTHOR]

Abstract: In this paper performance of a new piezoelectric fiber reinforced composite (PFRC) material has been investigated for active constrained layer damping (ACLD) of laminated thin simply supported composite cylindrical panels. The constraining layer of the ACLD treatment has been considered to be made of this PFRC material. A finite element model of smart composite panels integrated with the patches of such ACLD treatment has been developed to demonstrate the performance of these patches on enhancing the damping characteristics of thin cross-ply and angle-ply laminated composite cylindrical panels. Particular emphasis has been placed on studying the effect of variation of the piezoelectric fiber orientation in the constraining PFRC layer and the shallowness angle of the panels on the control authority of the patches. [Copyright &y& Elsevier]

Abstract: This paper deals with the derivation of a finite element model for the static analysis of functionally graded (FG) plates integrated with a layer of piezoelectric fiber reinforced composite (PFRC) material. The layer of PFRC material acts as the distributed actuator of the FG plates. The Young’s modulus of the FG plate is assumed to vary exponentially along the thickness of the plate while the Poisson’s ratio is assumed to be constant over the domain of the plate. The finite element model has been verified with the exact solutions for both thick and thin plates. Emphasis has been placed on investigating the effect of variation of piezoelectric fiber angle in the PFRC layer on its actuating capability of the FG plates. The finite element solutions also revealed that the activated PFRC layer is more effective in controlling the deformations of the FG plates when the layer is attached to the surface of the FG plate with minimum stiffness than when it is attached to the surface of the same with maximum stiffness. [Copyright &y& Elsevier]

Abstract: This paper deals with the analysis of active constrained layer damping (ACLD) of laminated thin composite shells using piezoelectric fiber reinforced composite (PFRC) materials. The constraining layer of the ACLD treatment is considered to be made of the PFRC materials. A finite element model of the smart composite shells integrated with the patches of such ACLD treatment has been developed to demonstrate the performance of these patches on enhancing the damping characteristics of thin symmetric and antisymmetric cross-ply and anti-symmetric angle ply laminated composite shells. The effect of variation of piezoelectric fiber orientation in the constraining PFRC layer on the control authority of the patches has also been investigated. [Copyright &y& Elsevier]

Static analysis of laminated smart composite plates integrated with a piezoelectric fiber, reinforced composite PFRC) layer acting as distributed actuators has been carried out by a generalized-energy-based finite element model. A simple first-order shear deformation theory is used for deriving the model. Eight noded isoparametric serendipity elements are used for discretizing the domain. The performance of the PFRC layer has been investigated for both symmetric and antisymmetric cross-ply and antisymmetric angle-ply laminated composite shell substrates. The effect of piezoelectric fiber orientation on the control authority of the PFRC layer has also been studied. [ABSTRACT FROM AUTHOR]

A novel work demonstrates the effect of delamination in smart laminated composite beams on the performance of active constrained layer damping (ACLD) treatment. A finite element model has been derived to formulate the dynamics of the composite beams integrated with a patch of ACLD treatment and a patch of piezoelectric film acting as a distributed sensor with and without the presence of delamination at different locations. Frequency response functions of the beams have been examined to observe the effect of delamination on the performance of ACLD treatment. It has been observed that the ACLD treatment improves the active damping characteristics of the beams, even in the presence of delamination, and that the responses of the beams are sensitive to the variation of the location of delamination. The responses due to active constrained layer damping presented may provide a useful guide to detect the presence of delamination in smart composite beams by the use of the existing numerical techniques. [ABSTRACT FROM AUTHOR]

A simple method for optimal control of vibrations of simply supported thin laminated shells integrated with piezoelectric layers is presented. The piezoelectric layers act as the distributed sensors and actuators. Coupled electromechanical governing equations of motion are derived using Hamilton's variational principle. The algorithm for a linear quadratic regulator with output feedback has been employed to formulate the optimal control problem. Controlled responses for various design parameters are illustrated, and a study of the effect of variation of the central angle subtended by the shell on the performance of the actuator is presented. [ABSTRACT FROM AUTHOR]

Presents a study that formulated a zeroth-order deformation theory for static and dynamic analysis of laminated composite plates. Analysis of the laminated plates using the theory; Comparison of the theoretical responses for symmetric and antisymmetric laminates with existing solutions; Suggestions regarding the use of the theory for both thick and thin laminated composite plates with high accuracy.

The effective coefficients of piezoelectric fiber-reinforced composites (PFRC) have been determined through micromechanical analyzes. The method of cells (MOC) and the strength of materials (SM) approach have been employed to predict the coefficients. A constant electric field is considered in the direction transverse to the fiber direction and is assumed to be the same both in the fiber and the matrix. MOC and SM predictions for the effective piezoelectric coefficient of the PFRC assessing the actuating capability in the fiber direction are in excellent agreement. It has been found for the piezoelectric fibers considered that, when the fiber volume fraction exceeds a critical fiber volume fraction, this effective piezoelectric coefficient becomes significantly larger than the corresponding coefficient of the piezoelectric material of the fiber. The methods also show the excellent matching of the predictions of the effective elastic constants and the dielectric constant of the PFRC in the useful range of fiber volume fraction. [ABSTRACT FROM AUTHOR]

Presents information on a study which obtained a closed-form solution for the optimal control of vibrations of a symmetric thin laminated plate integrated with piezoelectric layers. Information on the plate model; Results; Conclusions.

Presents a generalized finite element formulation for active vibration control of a laminated plate integrated with piezoelectric polymer layers acting as distributed sensors and actuators. Derivation of an eight-noded two-dimensional quadratic quadrilateral isoparametric element; Reduction in vibration amplitude.

In this paper, the performance of elliptical smart constrained layer damping treatments on active damping of geometrical nonlinear vibrations of smart laminated composite plates are analyzed. The constraining layers of the damping treatments are comprised of vertically/obliquely reinforced 1–3 piezoelectric composites, while the constrained layers are of isotropic viscoelastic material, modelled using the three dimensional fractional order derivative model. A meshfree model of the smart composite plate is developed for analyzing its nonlinear transient responses within the framework of a layerwise shear and normal deformation theory considering the von-Kármán type geometric nonlinearity. Thin composite plates integrated with elliptical/rectangular patches of the smart constrained layer damping treatments and having different stacking sequences and boundary conditions are considered for presenting the numerical results. The numerical analyses demonstrate the higher effectiveness of the elliptical patches over the rectangular ones in attenuating the nonlinear vibrations of laminated composite plates. [ABSTRACT FROM AUTHOR]

The present study addresses the static bending analysis of a dielectric nanobeam subjected to external electro-mechanical loads, considering the flexoelectric coupling, surface elasticity (SE) and surface residual stresses (SRS). In the current model, surface energies corresponding to the surface elastic strains and a traction jump across surfaces, based on the generalized Youngs-Laplace model, have been included. The numerical analysis is carried out by deriving the element free Galerkin (EFG) model for the dielectric beam based on a moving least squares (MLS) interpolation of the field variables. The effect of SE and SRS over the flexoelectric behaviour of the dielectric nanobeam are thoroughly examined here. The contrary effects of SE over the converse and direct flexoelectric behaviour is noted here. The effect of the SRS is observed to be dependent on the electrical field gradients. The present study reveals the significance of the SE and SRS for analysis involving flexoelectric behaviour in nano-sensors and actuators. • Significance of surface effects over exoelectric response is investigated. • Surface elasticity affects both direct and converse exoelectric behaviour. • Influence of surface residual stress depends on electromechanical boundary conditions. • Effect of surface residual stress depends on the deformed curvature. [ABSTRACT FROM AUTHOR]

This paper is concerned with the analysis of active constrained layer damping (ACLD) of geometrically nonlinear vibrations of doubly curved sandwich shells with facings composed of fuzzy fiber reinforced composite (FFRC). FFRC is a novel composite where the short carbon nanotubes (CNTs) which are either straight or wavy are radially grown on the periphery of the long continuous carbon fiber reinforcements. The plane of waviness of the CNTs is coplanar with the plane of carbon fiber. The constraining layer of the ACLD treatment is composed of the vertically/obliquely reinforced 1–3 piezoelectric composites (PZCs) while the constrained viscoelastic layer has been sandwiched between the substrate and the PZC layer. The Golla–Hughes–McTavish (GHM) method has been implemented to model the constrained viscoelastic layer of the ACLD treatment in time domain. A three dimensional finite element (FE) model of smart doubly curved FFRC sandwich shells integrated with ACLD patches has been developed to investigate the performance of these patches for controlling the geometrically nonlinear vibrations of these shells. This study reveals that the performance of the ACLD patches for controlling the geometrically nonlinear vibrations of the doubly curved sandwich shells is better in the case of the facings composed of laminated FFRC than that in the case of the facings made of conventional orthotropic laminated composite. The research carried out in this paper brings to light that even the wavy CNTs can be properly utilized for attaining structural benefits from the exceptional elastic properties of CNTs. [ABSTRACT FROM AUTHOR]

Abstract: A novel fuzzy carbon fiber heat exchanger (FFHE) is proposed in this study. The novel constructional feature of the FFHE is that the sinusoidally wavy carbon nanotubes (CNTs) are radially grown on the outer circumferential surface of the hollow cylindrical carbon fiber (HCF) heat exchanger. The effective thermal conductivities of the FFHE have been estimated by employing the method of cells (MOC) approach and the effective medium (EM) approach. The present study reveals that if the amplitudes of the radially grown sinusoidally wavy CNTs are parallel to the axis of the HCF then the effective axial thermal conductivity of the FFHE is significantly improved over that of the bare HCF heat exchanger (i.e., without CNTs). On the other hand, if the amplitudes of the radially grown wavy CNTs are transverse to the axis of the HCF, the effective transverse thermal conductivity of the FFHE is significantly improved over that of the bare HCF heat exchanger. It is also found that the CNT/polymer matrix interfacial thermal resistance does not affect the effective thermal conductivities of the FFHE. The present investigation suggests that exploiting the waviness of radially grown CNTs on the HCF a truly multifunctional and promising heat exchanger can be developed for advanced technological applications. [Copyright &y& Elsevier]

This article reports modeling of effective thermomechanical properties of multifunctional carbon nanotube (CNT)‐reinforced hybrid polymeric composites (hereafter, it is referred as "fuzzy fiber composite"). The novel constructional feature of fuzzy fiber composite (FFC) is that nanoscale CNTs are radially grown on the circumferential surfaces of microscale carbon fibers. Several micromechanical models were developed to predict the effective thermomechanical properties of FFC. The waviness of CNTs is intrinsic to many manufacturing processes and it influences thermomechanical behavior of two‐phase CNT‐reinforced composites. Therefore, an endeavor was also made to investigate the effect of wavy CNTs on the effective thermomechanical properties of FFC. The proposed modeling approach was applied to a heat exchanger made of FFC to determine its effective thermal conductivities. The findings of our study suggest that FFC containing nano‐ and micro‐scale fillers show improved thermomechanical properties and are promising next‐generation polymeric composites for advanced structural applications. POLYM. COMPOS., 39:4148–4164, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Presents a case of endocarditis due to Granulicatella adiacens. Infections caused by the genus Granulicatella; Isolation of the bacterium on chocolate agar containing pyridoxal; Benefits of two-dimensional transthoracic echocardiography.