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Dimitris A. Saravanos - One of the best experts on this subject based on the ideXlab platform.
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high order Layerwise finite element for the damped free vibration response of thick composite and sandwich composite plates
International Journal for Numerical Methods in Engineering, 2009Co-Authors: Theofanis S. Plagianakos, Dimitris A. SaravanosAbstract:A high-order Layerwise finite element methodology is presented, which enables prediction of the damped dynamic characteristics of thick composite and sandwich composite plates. The through-thickness displacement field in each Discrete Layer of the laminate includes quadratic and cubic polynomial distributions of the in-plane displacements, in addition to the linear approximations assumed by linear Layerwise theories. Stiffness, mass and damping matrices are formulated from ply to structural level. Interlaminar shear stress compatibility conditions are imposed on the Discrete Layer matrices, leading to both size reduction and prediction of interlaminar shear stresses at the laminate interfaces. The C1 continuous finite element implemented yields an element damping matrix in addition to element stiffness and mass matrices. Application cases include thick [0/90/0], [±θ]S and [±θ] composite plates with interlaminar damping Layers and sandwich plates with composite faces and foam core. In the latter case, modal frequencies and damping were also experimentally determined and compared with the finite element predictions. Copyright © 2008 John Wiley & Sons, Ltd.
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Higher-order Layerwise laminate theory for the prediction of interlaminar shear stresses in thick composite and sandwich composite plates
Composite Structures, 2009Co-Authors: Theofanis S. Plagianakos, Dimitris A. SaravanosAbstract:A higher-order Layerwise theoretical framework is presented, which enables prediction of the static response of thick composite and sandwich composite plates. The displacement field in each Discrete Layer through the thickness of the laminate includes quadratic and cubic polynomial distributions of the in-plane displacements, in addition to the linear approximations assumed by linear Layerwise theories. In-plane and interlaminar shear stiffness matrices of each Discrete Layer are formulated and interlaminar shear stress compatibility conditions are subsequently imposed to ensure continuity of interlaminar shear stresses through the thickness. A Ritz-type exact solution is further implemented to yield the structural response of thick composite and sandwich composite plates. The advantage of the present formulation in comparison to linear Layerwise theories lies in the small number of Discrete Layers used to model the thick composite laminate through-thickness and in the prediction of interlaminar shear stresses at the interface.
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Coupled High-Order Shear Layerwise Analysis of Adaptive Sandwich Piezoelectric Composite Beams
AIAA Journal, 2005Co-Authors: Theofanis S. Plagianakos, Dimitris A. SaravanosAbstract:A high-order Discrete Layer theoretical framework and a finite element are presented for predicting the electrostatic response of multifunctional beams with piezoelectric Layers. A new Layerwise coupled piezoelectric laminate theory is developed, in which quadratic and cubic fields are added to the in-plane displacement and electric potential approximation in each Discrete Layer. Interlaminar shear stress continuity is imposed through the thickness. Stiffness, piezoelectric, and permittivity matrices are formulated from ply to structural level. A finite element method and a beam element are further developed and used to predict the electrostatic response of piezocomposite beams. Numerical results and comparisons with linear Layerwise beam finite element predictions illustrate the accuracy and capability of the developed mechanics to capture the local electric and shear stress response of smart piezoelectric composite beams efficiently and accurately, including beams of high thickness, beams with sandwiched foam cores, and/or beams with compliant shear Layers.
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High-order Layerwise mechanics and finite element for the damped dynamic characteristics of sandwich composite beams
International Journal of Solids and Structures, 2004Co-Authors: Theofanis S. Plagianakos, Dimitris A. SaravanosAbstract:A high-order Discrete-Layer theory and a finite element are presented for predicting the damping of laminated composite sandwich beams. The new Layerwise laminate theory involves quadratic and cubic terms for approximation of the in-plane displacement in each Discrete Layer, while interlaminar shear stress continuity is imposed through the thickness. Integrated damping mechanics are formulated and both laminate and structural stiffness, mass and damping matrices are formed. A finite element method and a beam element are further developed for predicting the free vibration response, including modal frequencies, modal loss factors and through-thickness mode shapes. Numerical results and evaluations of the present model are shown. Modal frequencies and damping of sandwich composite beams are measured and correlated with predicted values. Finally, parametric studies illustrate the effect of core thickness and face lamination on modal damping and frequency values.
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Layerwise mechanics and finite element model for laminated piezoelectric shells
AIAA Journal, 1996Co-Authors: Paul R. Heyliger, Kuang-chih Pei, Dimitris A. SaravanosAbstract:A Discrete-Layer shell theory and associated finite element model is constructed for general laminated piezoelectric composite shells. The Discrete-Layer shell theory is based on linear piezoelectricity and accounts for general through-thickness variations of displacement and electrostatic potential by implementing one-dimensional piece-wise continuous Lagrange interpolation approximations over a specified number of subLayers. The formulation applies to shells of general shape and lamination. Initially, the static and dynamic behavior of a simply supported flat plate is studied to compare with available exact solutions, with excellent agreement being obtained. Static loading and free vibration of a cylindrical ring are then considered to evaluate the element and to study the fundamental behavior of active/sensory piezoelectric shells.
J. Vantomme - One of the best experts on this subject based on the ideXlab platform.
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Thermal, electrical, mechanical coupled mechanics for initial buckling analysis of smart plates and beams using Discrete Layer kinematics
International Journal of Solids and Structures, 2006Co-Authors: G. Giannopoulos, F. Santafe, J. Monreal, J. VantommeAbstract:Non-linear behavior of smart structures is of interest to researchers due to the possibilities for the elaboration of more effective actuators and sensors based on piezoelectric materials. The aim of the present work, is to present an integrated approach for the buckling behavior of smart beams and plates under multiple loading conditions. In order to present an accurate analysis, a coupled constitutive formulation between thermal, electrical and mechanical fields is elaborated incorporating non-linearity due to large displacements. An 8-node plate element was implemented in combination with Discrete Layer kinematics (LW) for the through-the-thickness representation of the structure. The issues of the critical buckling load under different electrical conditions as well as thermal and electrical loading are also presented. Experimental results contribute to the verification of the accuracy of the numerical analysis results and of the coupling mechanics in general.
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A thermal?electrical?mechanical coupled FE formulation using Discrete Layer kinematics for the dynamic analysis of smart plates
Smart Materials and Structures, 2006Co-Authors: G. Giannopoulos, J. VantommeAbstract:The use of piezoelectric elements has been increasing in recent years for different applications. In aeronautics their use is spread over disciplines from noise and vibration control to shape control. The inherent complexity of smart structure analysis requires the establishment of powerful tools to capture the different aspects of their performance. The current work presents the dynamic analysis of composite plates incorporating piezoelectric Layers. In order to perform this analysis a coupled finite element solver has been developed, based on a 4-node plate finite element incorporating Discrete Layer kinematic assumptions. The implemented constitutive formulation permits us to assess the dynamic performance of a smart plate under different thermal, mechanical and electrical conditions. In addition, the Discrete Layer kinematic assumptions as well as the assumption of deformability through the thickness, permit the accurate prediction of the stress levels in every Layer and also the voltage and temperature response. The influence of the coupling between thermal, electrical and mechanical fields for different modes is also presented, which shows that the influence of coupling depends on the mode. In addition, the model is also validated for thin plate applications.
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Thermal-electrical-mechanical coupled FE buckling analysis of smart plates using Discrete Layer kinematics
Smart Structures and Materials 2006: Modeling Signal Processing and Control, 2006Co-Authors: G. Giannopoulos, F. Santafe Iribarren, J. VantommeAbstract:In the present work, the non-linear analysis of smart beams and plates is performed, using FE techniques. A coupled constitutive formulation between thermal, electrical and mechanical fields is presented incorporating non-linearity due to large displacements. An 8-node plate element was implemented in combination with a Discrete Layer approximation (LW) for the through the thickness representation of the structure. The issues of the critical buckling load under different electrical conditions as well as thermal and electrical loading are also presented. Experimental results contribute in order to verify the numerical analysis results.
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A fully thermoelectromechanically coupled FE analysis for the dynamic behavior of smart plates using Discrete-Layer kinematics
Smart Structures and Materials 2005: Modeling Signal Processing and Control, 2005Co-Authors: G. Giannopoulos, J. VantommeAbstract:Due to the extended application of piezoelectrics into a number of high performance structures, the necessity for accurate analysis of their behavior is of critical importance. In this work the dynamic analysis of a composite plate incorporating piezoelectric Layers is presented. A 4-node plate finite element is developed. Discrete Layer kinematic assumptions in combination with a thermal-electrical-mechanical coupled formulation takes place. This formulation enables the investigation of the response of a structure under the influence of different thermal and electrical conditions. Additionally, in order to investigate whether the kinematics assumptions implemented here are capable of capturing with accuracy the dynamic performance of both thin and thick structures, plates of different thicknesses are investigated.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
G. Giannopoulos - One of the best experts on this subject based on the ideXlab platform.
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Thermal, electrical, mechanical coupled mechanics for initial buckling analysis of smart plates and beams using Discrete Layer kinematics
International Journal of Solids and Structures, 2006Co-Authors: G. Giannopoulos, F. Santafe, J. Monreal, J. VantommeAbstract:Non-linear behavior of smart structures is of interest to researchers due to the possibilities for the elaboration of more effective actuators and sensors based on piezoelectric materials. The aim of the present work, is to present an integrated approach for the buckling behavior of smart beams and plates under multiple loading conditions. In order to present an accurate analysis, a coupled constitutive formulation between thermal, electrical and mechanical fields is elaborated incorporating non-linearity due to large displacements. An 8-node plate element was implemented in combination with Discrete Layer kinematics (LW) for the through-the-thickness representation of the structure. The issues of the critical buckling load under different electrical conditions as well as thermal and electrical loading are also presented. Experimental results contribute to the verification of the accuracy of the numerical analysis results and of the coupling mechanics in general.
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A thermal?electrical?mechanical coupled FE formulation using Discrete Layer kinematics for the dynamic analysis of smart plates
Smart Materials and Structures, 2006Co-Authors: G. Giannopoulos, J. VantommeAbstract:The use of piezoelectric elements has been increasing in recent years for different applications. In aeronautics their use is spread over disciplines from noise and vibration control to shape control. The inherent complexity of smart structure analysis requires the establishment of powerful tools to capture the different aspects of their performance. The current work presents the dynamic analysis of composite plates incorporating piezoelectric Layers. In order to perform this analysis a coupled finite element solver has been developed, based on a 4-node plate finite element incorporating Discrete Layer kinematic assumptions. The implemented constitutive formulation permits us to assess the dynamic performance of a smart plate under different thermal, mechanical and electrical conditions. In addition, the Discrete Layer kinematic assumptions as well as the assumption of deformability through the thickness, permit the accurate prediction of the stress levels in every Layer and also the voltage and temperature response. The influence of the coupling between thermal, electrical and mechanical fields for different modes is also presented, which shows that the influence of coupling depends on the mode. In addition, the model is also validated for thin plate applications.
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Thermal-electrical-mechanical coupled FE buckling analysis of smart plates using Discrete Layer kinematics
Smart Structures and Materials 2006: Modeling Signal Processing and Control, 2006Co-Authors: G. Giannopoulos, F. Santafe Iribarren, J. VantommeAbstract:In the present work, the non-linear analysis of smart beams and plates is performed, using FE techniques. A coupled constitutive formulation between thermal, electrical and mechanical fields is presented incorporating non-linearity due to large displacements. An 8-node plate element was implemented in combination with a Discrete Layer approximation (LW) for the through the thickness representation of the structure. The issues of the critical buckling load under different electrical conditions as well as thermal and electrical loading are also presented. Experimental results contribute in order to verify the numerical analysis results.
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A fully thermoelectromechanically coupled FE analysis for the dynamic behavior of smart plates using Discrete-Layer kinematics
Smart Structures and Materials 2005: Modeling Signal Processing and Control, 2005Co-Authors: G. Giannopoulos, J. VantommeAbstract:Due to the extended application of piezoelectrics into a number of high performance structures, the necessity for accurate analysis of their behavior is of critical importance. In this work the dynamic analysis of a composite plate incorporating piezoelectric Layers is presented. A 4-node plate finite element is developed. Discrete Layer kinematic assumptions in combination with a thermal-electrical-mechanical coupled formulation takes place. This formulation enables the investigation of the response of a structure under the influence of different thermal and electrical conditions. Additionally, in order to investigate whether the kinematics assumptions implemented here are capable of capturing with accuracy the dynamic performance of both thin and thick structures, plates of different thicknesses are investigated.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Paul R. Heyliger - One of the best experts on this subject based on the ideXlab platform.
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Coupled fields in Layered thermomagnetoelectroelastic spheres
Journal of Intelligent Material Systems and Structures, 2018Co-Authors: Sl Divya Dinavahi, Paul R. Heyliger, Jiangyi Chen, Ernian PanAbstract:A Discrete-Layer model is presented and applied to Layered anisotropic spheres with coupling among the elastic, electric, magnetic, and temperature fields under static conditions. The governing dif...
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Discrete Layer solution to free vibrations of functionally graded magneto electro elastic plates
Mechanics of Advanced Materials and Structures, 2006Co-Authors: Fernando Ramírez, Paul R. HeyligerAbstract:Natural frequencies of orthotropic magneto-electro-elastic graded composite plates are determined using a Discrete Layer model with two different approaches. In the first, the functions describing the gradation of the materials properties through the thickness of the plate are incorporated into the governing equations. In the second approach, the plate is divided into a finite number of homogeneous Layers. The model is validated by comparing the natural frequencies of a simply supported Al/ZrO2 graded square plate with the exact solution. Excellent agreement is obtained. Rectangular plates with different boundary conditions, aspect ratios, and made of different types of composite materials are also considered: Al/ZrO2 and BaTiO3/CoFe2O4 plates for which the volume fraction of the phases change as a function of the z coordinate, graphite/epoxy plates with the orientation of the fibers changing through the thickness of the plate, and plates having an exponential variation of the material properties. Applica...
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static analysis of functionally graded elastic anisotropic plates using a Discrete Layer approach
Composites Part B-engineering, 2006Co-Authors: Fernando Ramírez, Paul R. HeyligerAbstract:An approximate solution for the static analysis of three-dimensional, anisotropic, elastic plates composed of functionally graded materials (FGM) is presented. The solution is obtained by using a Discrete Layer theory in combination with the Ritz method in which the plate is divided into an arbitrary number of homogeneous and/or FGM Layers. Two types of functionally graded materials are considered: an exponential variation of the mechanical properties through the thickness of the plate, and mechanical properties as a function of the fiber orientation, which varies quadratically through the laminate thickness. The present approach is not dependent on a specific transition function, and any continuous function representing the variation of the material properties in the thickness direction may be incorporated in the model. The method is validated by solving the problem of a single simply supported FGM plate, for which excellent agreement with the exact solution is obtained. Two more examples with different boundary conditions and different material configurations are presented in order to demonstrate the applicability of this solution. Homogeneous, graded, and bi-Layer plates are examined in order to study potential advantages of using FGM.
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Mode-selective resonance ultrasound spectroscopy of a Layered parallelepiped
The Journal of the Acoustical Society of America, 2000Co-Authors: Hirotsugu Ogi, Paul R. Heyliger, Hassel Ledbetter, Sudook KimAbstract:The resonance frequencies of mechanical free vibration of a three-Layer material calculated by a Discrete-Layer model and measured by acoustic-resonance methods were compared. The material was composed of an aluminum parallelepiped sandwiched by two stainless-steel parallelepipeds. The Discrete-Layer model developed here used linear Lagrange basis functions through the Layered dimension and continuous global power-series basis functions in the plane perpendicular to the Layer thickness. Using such a basis function for the Layer-thickness direction allows discontinuity in the elastic properties across the interface between dissimilar Layers. The resonance frequencies were measured using two methods: mode-selective electromagnetic acoustic resonance (EMAR) and resonance ultrasound spectroscopy (RUS). The measurements agreed with the calculations typically within 1%. The EMAR method allows the selective detection of vibrational modes possessing particular displacement patterns. This selectivity was supported...
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Electroelastic fields in Layered piezoelectric spheres
International Journal of Engineering Science, 1999Co-Authors: Paul R. HeyligerAbstract:Analytic and Discrete-Layer models are used to study the displacement and electrostatic potential fields in the static and free vibration response of Layered piezoelectric spheres. The analytic solution is developed for the lowest harmonic for purposes of comparison. The Discrete-Layer model is based on approximations to the variational form of the equations of motion and the charge equation. The displacements and electrostatic potential are separated into functions in the radial direction of the sphere and those for spherical surfaces. General expressions are given for arbitrary approximation functions. For purposes of numerical examples, piecewise quadratic Lagrange interpolation polynomials are used in the radial direction, with spherical harmonics in the circumferential and azimuthal directions. The results from these numerical models are compared with earlier studies for elastic spheres, and several new results are presented for Layered piezoelectric spheres.
Theofanis S. Plagianakos - One of the best experts on this subject based on the ideXlab platform.
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high order Layerwise finite element for the damped free vibration response of thick composite and sandwich composite plates
International Journal for Numerical Methods in Engineering, 2009Co-Authors: Theofanis S. Plagianakos, Dimitris A. SaravanosAbstract:A high-order Layerwise finite element methodology is presented, which enables prediction of the damped dynamic characteristics of thick composite and sandwich composite plates. The through-thickness displacement field in each Discrete Layer of the laminate includes quadratic and cubic polynomial distributions of the in-plane displacements, in addition to the linear approximations assumed by linear Layerwise theories. Stiffness, mass and damping matrices are formulated from ply to structural level. Interlaminar shear stress compatibility conditions are imposed on the Discrete Layer matrices, leading to both size reduction and prediction of interlaminar shear stresses at the laminate interfaces. The C1 continuous finite element implemented yields an element damping matrix in addition to element stiffness and mass matrices. Application cases include thick [0/90/0], [±θ]S and [±θ] composite plates with interlaminar damping Layers and sandwich plates with composite faces and foam core. In the latter case, modal frequencies and damping were also experimentally determined and compared with the finite element predictions. Copyright © 2008 John Wiley & Sons, Ltd.
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Higher-order Layerwise laminate theory for the prediction of interlaminar shear stresses in thick composite and sandwich composite plates
Composite Structures, 2009Co-Authors: Theofanis S. Plagianakos, Dimitris A. SaravanosAbstract:A higher-order Layerwise theoretical framework is presented, which enables prediction of the static response of thick composite and sandwich composite plates. The displacement field in each Discrete Layer through the thickness of the laminate includes quadratic and cubic polynomial distributions of the in-plane displacements, in addition to the linear approximations assumed by linear Layerwise theories. In-plane and interlaminar shear stiffness matrices of each Discrete Layer are formulated and interlaminar shear stress compatibility conditions are subsequently imposed to ensure continuity of interlaminar shear stresses through the thickness. A Ritz-type exact solution is further implemented to yield the structural response of thick composite and sandwich composite plates. The advantage of the present formulation in comparison to linear Layerwise theories lies in the small number of Discrete Layers used to model the thick composite laminate through-thickness and in the prediction of interlaminar shear stresses at the interface.
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Coupled High-Order Shear Layerwise Analysis of Adaptive Sandwich Piezoelectric Composite Beams
AIAA Journal, 2005Co-Authors: Theofanis S. Plagianakos, Dimitris A. SaravanosAbstract:A high-order Discrete Layer theoretical framework and a finite element are presented for predicting the electrostatic response of multifunctional beams with piezoelectric Layers. A new Layerwise coupled piezoelectric laminate theory is developed, in which quadratic and cubic fields are added to the in-plane displacement and electric potential approximation in each Discrete Layer. Interlaminar shear stress continuity is imposed through the thickness. Stiffness, piezoelectric, and permittivity matrices are formulated from ply to structural level. A finite element method and a beam element are further developed and used to predict the electrostatic response of piezocomposite beams. Numerical results and comparisons with linear Layerwise beam finite element predictions illustrate the accuracy and capability of the developed mechanics to capture the local electric and shear stress response of smart piezoelectric composite beams efficiently and accurately, including beams of high thickness, beams with sandwiched foam cores, and/or beams with compliant shear Layers.
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High-order Layerwise mechanics and finite element for the damped dynamic characteristics of sandwich composite beams
International Journal of Solids and Structures, 2004Co-Authors: Theofanis S. Plagianakos, Dimitris A. SaravanosAbstract:A high-order Discrete-Layer theory and a finite element are presented for predicting the damping of laminated composite sandwich beams. The new Layerwise laminate theory involves quadratic and cubic terms for approximation of the in-plane displacement in each Discrete Layer, while interlaminar shear stress continuity is imposed through the thickness. Integrated damping mechanics are formulated and both laminate and structural stiffness, mass and damping matrices are formed. A finite element method and a beam element are further developed for predicting the free vibration response, including modal frequencies, modal loss factors and through-thickness mode shapes. Numerical results and evaluations of the present model are shown. Modal frequencies and damping of sandwich composite beams are measured and correlated with predicted values. Finally, parametric studies illustrate the effect of core thickness and face lamination on modal damping and frequency values.