Modeling Of Composite Plates Research Articles

ANN prediction model for composite plates against low velocity impact loads using finite element analysis

In this paper, the use of Artificial Neural Networks to predict the absorbed energy in the composite plates impacted with low velocity is described. The impact response of a composite laminate depends upon various factors such as thickness, stacking sequence and number of layers. These factors are identified in an earlier study using the sensitivity analysis. These factors have the most prominent effect on the impact resistance of the composite plates. These are studied here with the help of design of experiments so that a suitable data set is obtained. The ability to solve a large number of simulations using FEA gives an advantage in the design optimization with the help of DOE (Design of Experiments). During the study different variations of these factors were tried and the response in terms of the absorbed energy was estimated. The simulation results were then used along with the ANN (Artificial Neural Networks) to fit a function to estimate the amount of absorbed energy. The results from the DOE follow the intuition that the increase of thickness and number of layers increase the performance of the composite plates. The ANN model is trained such that it is able to predict with an acceptable accuracy range the amount of absorbed energy for different configurations of input variables. The paper discusses the codification of input variables so that they can be used to train ANN model. Also, the use of differential evolution algorithm is discussed which is used to select the best possible ANN model based on the maximum error and root mean square error of the ANN models.

Identification of Thin Film Stress Based on Mindlin-Reissner Plate Finite Element Method

In the present work, a thin film stress identification procedure based on the finite element method is developed. A model of two-layer composite plates with thin film stress is established in the framework of the Mindlin-Reissner plate theory. A strategy of the least square method with regularization based on the derivations of smoothed elemental thin film stress is introduced to identify thin film stress using experimentally measurable deflection fields as objective variables. The method is applicable for thin or moderately thick plates, complicated geometry, different material compositions, and variant thin film stress fields due to the flexibility of the finite element method.

Hygrothermal effects on free vibration of delaminated woven fiber composite plates – Numerical and experimental results

The present study deals with numerical and experimental investigations on free vibration behavior of woven fiber Glass/Epoxy delaminated composite plates subjected to elevated temperatures and moistures. A composite plate model based on first order shear deformation theory (FSDT) with provision of mid plane square delamination is considered for free vibration of delaminated composite plates subjected to hygrothermal loading. An eight noded quadratic isoparametric element with five degrees of freedom per node is used in the formulation. A series of experiments is conducted to obtain natural frequencies of vibration for woven fiber Glass/Epoxy delaminated composite plates using B&K FFT analyzer with PULSE software, which agree reasonably well with the numerical values. Teflon film is embedded in the laminate, simulating the presence of delamination. The effects of temperature, moisture, delamination size and different boundary conditions on the natural frequencies of composite plates are investigated. The results indicate that the vibration behavior is greatly influenced by the delamination and hygrothermal parameters involved in the study.

C0 triangular elements based on the Refined Zigzag Theory for multilayer composite and sandwich plates

The Refined Zigzag Theory (RZT) has been recently developed for the analysis of homogeneous, multilayer composite and sandwich plates. The theory has a number of practical and theoretical advantages over the widely used First-order Shear Deformation Theory (FSDT) and other types of higher-order and zigzag theories. Using FSDT as a baseline, RZT takes into account the stretching, bending, and transverse shear deformations. Unlike FSDT, this novel theory does not require shear correction factors to yield accurate results for a wide range of material systems including homogeneous, laminated composite, and sandwich laminates. The inplane zigzag kinematic assumptions, which compared to FSDT add two additional rotation-type kinematic variables, give rise to two types of transverse shear strain measures – the classical average shear strain (as in FSDT) and another one related to the cross-sectional distortions enabled by the zigzag kinematic terms. Consequently, with a fixed number of kinematic variables, the theory enables a highly accurate modeling of multilayer composite and sandwich plates even when the laminate stacking sequence exhibits a high degree of transverse heterogeneity. Unlike most zigzag formulations, this theory is not affected by such theoretical anomalies as the vanishing of transverse shear stresses and forces along clamped boundaries.In this paper, six- and three-node, C0-continuous, RZT-based triangular plate finite elements are developed; they provide the best compromise between computational efficiency and accuracy. The element shape functions are based on anisoparametric (aka interdependent) interpolations that ensure proper element behavior even when very thin plates are modeled. Continuous edge constraints are imposed on the transverse shear strain measures to derive coupled-field deflection shape functions, resulting in a simple and efficient three-node element. The elements are implemented in ABAQUS – a widely used commercial finite element code – by way of a user-element subroutine.The predictive capabilities of the new elements are assessed on several elasto-static problems, which include simply supported and cantilevered laminated composite and sandwich plates. The numerical results demonstrate that the new RZT-based elements provide superior predictions for modeling a wide range of laminates including highly heterogeneous sandwich laminations. They also offer substantial improvements over the existing plate elements based on FSDT as well as other higher-order and zigzag-type elements.

The Strain Energy Tuning of the Shape Memory Alloy on the Post-Buckling of Composite Plates Using Finite Element Method

This paper presents a geometric non-linear finite element model of shape memory alloy composite plates and its source code in order to determine critical loads and to trace post-buckling paths of the composite plates. A numerical study was conducted on symmetric and anti-symmetric angle-ply and cross-ply composite plates. Buckling and post-buckling improvements of composite plates due to the shape memory effect behaviour of shape memory alloy were carried out. The pre-strained shape memory alloy wires were embedded within laminated composite plates so that recovery stress could be induced with the heated wires. The methods of active property tuning and active strain energy tuning were applied to show the various effects of the shape memory alloy on the studied behaviour. The result showed that significant improvements occurred in the critical loads and the post-buckling paths of the symmetric and anti-symmetric angle-ply and the symmetric cross-ply composite plates due to the active strain energy tuning method. In the case of the anti-symmetric cross-ply composite plate where bifurcation point did not exist, the post-buckling path was substantially improved.

The Strain Energy Tuning of the Shape Memory Alloy on the Post-Buckling of Composite Plates Using Finite Element Method

This paper presents a geometric non-linear finite element model of shape memory alloy composite plates and its source code in order to determine critical loads and to trace post-buckling paths of the composite plates. A numerical study was conducted on symmetric and anti-symmetric angle-ply and cross-ply composite plates. Buckling and post-buckling improvements of composite plates due to the shape memory effect behaviour of shape memory alloy were carried out. The pre-strained shape memory alloy wires were embedded within laminated composite plates so that recovery stress could be induced with the heated wires. The methods of active property tuning and active strain energy tuning were applied to show the various effects of the shape memory alloy on the studied behaviour. The result showed that significant improvements occurred in the critical loads and the post-buckling paths of the symmetric and anti-symmetric angle-ply and the symmetric cross-ply composite plates due to the active strain energy tuning method. In the case of the anti-symmetric cross-ply composite plate where bifurcation point did not exist, the post-buckling path was substantially improved.

Mechanics of a nanocrystalline coating and grain-size dependence of its plastic strength

From the mechanics perspective the most critical properties of a coating material are likely its yield strength, hardness, and wear resistance. These properties are intimately related to each other as a material with high yield strength usually also possesses superior hardness and strong wear resistance. Our objective in this study is to seek for the strongest material state in terms of its plastic strength, and the critical grain size at which this strength can be attained. Based on the cross-sectional morphology of a nanocrystalline coating we first conceive a composite plate model consisting of the columnar grains and the grain boundary affiliated region (broadly called the GB zone), and present a plane-stress theory to investigate its in-plane behavior. We then make use of a linear comparison composite and a field fluctuation approach to explore the competition between the grain interior and the plastically softer GB zone as the grain size decreases from the coarse grain to the nanometer range. Based on the developed model the anisotropic stress–strain relations of a ZrN coating are illustrated as a function of grain size in both in-plane and out-of-plane directions. It is demonstrated that, as the grain size decreases, the variation of plastic strength in the Hall–Petch plot undergoes a transition from a positive to a negative slope, exhibiting the Hall–Petch and the inverse Hall–Petch effects. The strength-differential effect between tension and compression is also observed. The critical grain sizes at which the maximum strength develops are found to be lower along the out-of-plane direction than along the in-plane ones, and also lower under compression than under tension. Based on Tabor’s law, our calculated critical grain size for the hardness was about 16 nm, while a recent indentation test indicated a range of 14.2–19 nm. The existence of Hall–Petch, inverse Hall–Petch, and strength-differential effects, and of an optimal grain size, is thus theoretically proven for the first time for nanocrystalline coatings.

Modeling thick composite laminate and sandwich structures with linear viscoelastic damping

The paper describes the modeling of thick composite laminate and sandwich plates and beams with linear viscoelastic treatments. A discrete laminate model (DLM) is described, validated and compared to numerical spectral finite elements method (SFEM), finite element method (FEM) and experimental results. The DLM approach assumes each layer as thick laminate with orthotropic orientation, rotational inertia and transversal shearing, membrane and bending deformations. First order shear deformation theory is used. The equation of motion is developed following a wave approach based on discrete layer description. It handles symmetrical and asymmetrical layouts of unlimited number of transversal incompressible layers. Next, dilatational (symmetric mode) motion along the core’s thickness is considered to complete the DLM solution when applied to the case of symmetric sandwich structures with soft and thick core. The model is compared to a second approach employing spectral finite elements. The latter handles composite laminated plates and beams with orthotropic orientation. It is shown that both approaches estimate accurately the propagating wave solutions of laminated structures. Using these solutions, the input mobility and the mechanical impedance are computed. The two models are successfully compared to classical finite elements as well as to experimental results for different boundary conditions. Moreover, the equivalent damping loss factor of composite laminate plates with viscoelastic treatment is addressed and the influence of the heading direction is discussed.

Homogenization and dimensional reduction of composite plates with in-plane heterogeneity

The variational asymptotic method is used to construct a new model for composite plates which could have in-plane heterogeneity due to both geometry and material. We first formulate the original three-dimensional problem in an intrinsic form which is suitable for geometrically nonlinear analysis. Taking advantage of smallness of the plate thickness and heterogeneity, we use the variational asymptotic method to rigorously construct an effective plate model unifying a homogenization process and a dimensional reduction process. This approach is implemented in the computer code VAPAS using the finite element technique for the purpose of dealing with realistic heterogeneous plates. A few examples are used to demonstrate the capability of this new model.

C0-type global–local theory with non-zero normal strain for the analysis of thick multilayer composite plates

In this paper, an accurate and efficient C0-type third-order global---local model incorporating effects of the transverse normal strain is proposed to study the thermal/mechanical behaviors of thick multilayer cross-ply plates. Transverse displacement is assumed to be a linear distribution through the thickness direction, for which the normal strain could be readily computed. Based on the interlaminar continuity conditions of in-plane displacement and transverse shear stresses, layer-dependent variables could be reduced. Employing shear stress free condition at the upper and the lower surfaces, derivatives of transverse displacement are eliminated from the displacement field, so that C0 interpolation functions are only required for the finite element implementation. As a result, the number of variables is independent of the number of layers of the laminate. To assess the proposed model, the classical quadratic eight-node isoparametric element is used for the interpolation of all the displacement parameters defined at each nodal point on the composite plate. Comparing with various existing composite plate models, it is found that simple C0 finite elements with non-zero normal strain could produce accurate deformations and stresses of thick multilayer composite plates subjected to thermal and mechanical loads.

Modeling and analysis of laminate composite plates with embedded active–passive piezoelectric networks

The objective of this work is to present the finite element modeling of laminate composite plates with embedded piezoelectric patches or layers that are then connected to active–passive resonant shunt circuits, composed of resistance, inductance and voltage source. Applications to passive vibration control and active control authority enhancement are also presented and discussed. The finite element model is based on an equivalent single layer theory combined with a third-order shear deformation theory. A stress-voltage electromechanical model is considered for the piezoelectric materials fully coupled to the electrical circuits. To this end, the electrical circuit equations are also included in the variational formulation. Hence, conservation of charge and full electromechanical coupling are guaranteed. The formulation results in a coupled finite element model with mechanical (displacements) and electrical (charges at electrodes) degrees of freedom. For a Graphite-Epoxy (Carbon-Fibre Reinforced) laminate composite plate, a parametric analysis is performed to evaluate optimal locations along the plate plane ( xy) and thickness ( z) that maximize the effective modal electromechanical coupling coefficient. Then, the passive vibration control performance is evaluated for a network of optimally located shunted piezoelectric patches embedded in the plate, through the design of resistance and inductance values of each circuit, to reduce the vibration amplitude of the first four vibration modes. A vibration amplitude reduction of at least 10 dB for all vibration modes was observed. Then, an analysis of the control authority enhancement due to the resonant shunt circuit, when the piezoelectric patches are used as actuators, is performed. It is shown that the control authority can indeed be improved near a selected resonance even with multiple pairs of piezoelectric patches and active–passive circuits acting simultaneously.

Delamination identification of laminated composite plates using a continuum damagemechanics model and subset selection technique

In this paper, a new model-based delamination detection methodology is presented forlaminated composite plates and its performance is studied both numerically andexperimentally. This methodology consists of two main parts: (1) modal analysisof an undamaged baseline finite element (FE) model and experimental modaltesting of panels with delamination damage at single or multiple locations and (2) asensitivity based subset selection technique for single or multiple delamination damagelocalizations. As an identification model, a higher-order finite element model iscombined with a rational micromechanics-based CDM model which defines thedelamination damage parameter as a ratio of delaminated area to entire area. Thesubset selection technique based on sensitivity of the dynamic residual force hasbeen known to be capable of detecting multiple damage locations. However, therehas been no experimental study specifically for the applications in laminatedcomposite structures. To implement the methodology, a sensitivity matrix for thelaminated composite plate model has been derived. Applications of the proposedmethodology to an E-glass/epoxy symmetric composite panel composed of 16 plies[CSM/UM1208/3 layers of C1800]s = [CSM/0/(90/0)3]s with delamination damage are demonstrated both numerically and experimentally. Anon-contact scanning laser vibrometer (SLV), a lead zirconate titanate (PZT) actuator and apolyvinylidene fluoride (PVDF) sensor are used to conduct experimental modal testing.From the experimental example, capabilities of the proposed methodology for damageidentification are successfully demonstrated for a 2D laminated composite panel.Furthermore, various damage scenarios are considered to show its performance and detailedresults are discussed for future improvements.

Effect of matrix cracking and material uncertainty on composite plates

A laminated composite plate model based on first order shear deformation theory is implemented using the finite element method. Matrix cracks are introduced into the finite element model by considering changes in the A, B and D matrices of composites. The effects of different boundary conditions, laminate types and ply angles on the behavior of composite plates with matrix cracks are studied. Finally, the effect of material property uncertainty, which is important for composite material on the composite plate, is investigated using Monte Carlo simulations. Probabilistic estimates of damage detection reliability in composite plates are made for static and dynamic measurements. It is found that the effect of uncertainty must be considered for accurate damage detection in composite structures. The estimates of variance obtained for observable system properties due to uncertainty can be used for developing more robust damage detection algorithms.

133 曲線状強化繊維を有する複合材モデルの最適化と実験モード解析(積層複合版・シェルの振動-1,OS-13 板・シェル構造の振動・座屈と設計,総合テーマ「伝統を,未来へ!」)

The vibration characteristics of the composite plate model with curvilinear fibers are investigated in this study. The curvilinear fiber is realized by the plastic deformation of steel wires and the present composite model is composed of the curved steel wires and epoxy resin. The natural frequency and mode shape are obtained by the experimental modal analysis method where the plate is excited by the impulse hammer and acceleration response is measured. The experimental results showed that the present model has the specific skewed mode shape and it agrees well with the finite element analysis result in terms of the frequency and mode shape. Then the curvilinear fiber shape is optimized for the maximum fundamental frequency by using the genetic algorithm method. The numerical results showed that the optimum curvilinear fiber results in the higher fundamental frequency than the plate with typical curvilinear fibers.

A two-dimensional electromechanical composite plate model for piezoelectric micromachined ultrasonic transducers (pMUTs)

A two-dimensional composite plate model was developed as part of the design methodology for micro-scale thin membrane structures in general and pMUTs in particular. The model was compared with a one-dimensional beam model developed earlier and experimental measurements. The two-dimensional model was shown to converge to the one-dimensional model for the structures with a large aspect ratio. Compared to the experimental data, the qualitative trends regarding the dependence of transducer performance on the aspect ratio predicted by the model were validated by the experimental measurements in all cases except that of the electromechanical coupling factor k2eff. The quantitative agreement between model and experimental data was quite good for all parameters at a transducer width of 180 µm, and became worse as the transducer width became smaller. The resonance frequency was predicted very well by the model, and did not depend on the aspect ratio. With the enhanced flexibility provided by the two-dimensional model, some optimization study was also performed. It was found that among different geometries, a square membrane, i.e. a membrane with the aspect ratio equal to 1, appears to have the highest effective coupling coefficient. On the other hand, for a given square membrane, the electrode which covers about 25% of the membrane, i.e. 50% of the width and length measured from the center, possesses the optimized coupling coefficient. In practice, the model can be used to first optimize the dimension of the membrane for pMUTs to obtain the targeted frequencies and then the electrode coverage area for optimized coupling coefficient.

Finite element modeling of composite plates with internal delamination

A three-dimensional (3D) finite element model of delaminated fiber-reinforced composite plates is developed to analyze their dynamics. Natural frequencies and modal displacements are calculated for various case studies with different dimensions and delamination characteristics. Numerical results showed a good agreement with available experimental data. A new proposed model shows enhancement of the accuracy of the results. This study also introduces a method for detecting delamination in composite plates.

Nonlinear modeling of composite plates with piezoceramic layers using finite element analysis

A finite element formulation for the vibration of piezoceramic laminated plates that takes hysteretic behavior into account is presented. Structural deformations of the layers are modeled using Mindlin plate theory where electro-mechanical coupling equations are formulated based on the same theory. Electro-mechanical coupling terms model orthotropic piezoelectric properties ( g 31≠ g 32), in addition to an orthotropic formulation for the mechanical properties of each plate layer. Lateral and transversal displacement fields are modeled with 8-node serendipity quadratic elements. Hysteretic behavior within the dielectric domain is implemented and simulated via the finite element method using an Ishlinskii model. Experimental hysteresis characterization for a single piezo layer and simulation results are presented. A coupled composite plate model is also tested under different loading conditions experimentally and numerically.

Space geodetic test of kinematic models for the Indo-Australian composite plate

Research Article| October 01, 2008 Space geodetic test of kinematic models for the Indo-Australian composite plate Richard G. Gordon; Richard G. Gordon * 11Department of Earth Science, Rice University, Houston, Texas 77005, USA *E-mail: rgg@rice.edu. Search for other works by this author on: GSW Google Scholar Donald F. Argus; Donald F. Argus 22Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA Search for other works by this author on: GSW Google Scholar Jean-Yves Royer Jean-Yves Royer 33Université Européenne de Bretagne à Brest, Centre National de la Recherche Scientifique, Institut Universitaire Européen de la Mer, Domaines Océaniques, 29280 Plouzané, France Search for other works by this author on: GSW Google Scholar Author and Article Information Richard G. Gordon * 11Department of Earth Science, Rice University, Houston, Texas 77005, USA Donald F. Argus 22Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA Jean-Yves Royer 33Université Européenne de Bretagne à Brest, Centre National de la Recherche Scientifique, Institut Universitaire Européen de la Mer, Domaines Océaniques, 29280 Plouzané, France *E-mail: rgg@rice.edu. Publisher: Geological Society of America Received: 23 May 2008 Revision Received: 03 Jul 2008 Accepted: 16 Jul 2008 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2008 Geological Society of America Geology (2008) 36 (10): 827–830. https://doi.org/10.1130/G25089A.1 Article history Received: 23 May 2008 Revision Received: 03 Jul 2008 Accepted: 16 Jul 2008 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Richard G. Gordon, Donald F. Argus, Jean-Yves Royer; Space geodetic test of kinematic models for the Indo-Australian composite plate. Geology 2008;; 36 (10): 827–830. doi: https://doi.org/10.1130/G25089A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The existence of a distinct Capricorn component plate within the composite Indo-Australian plate has previously been questioned. If there is no Capricorn plate, the global positioning system site at Bangalore (on the Indian plate) is predicted to move relative to the Australian plate at a velocity of 10 mm yr−1. If there is a distinct Capricorn plate, Bangalore is predicted to move relative to the Australian plate at a velocity of 17 mm yr−1. Space geodetic data from Australia and India are accurate enough to provide quantitative tests of this prediction and to discriminate between alternative composite plate models. The data best fit a composite plate model that assumes the existence of a distinct Capricorn component plate moving relative to both the Indian and Australian component plates. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

An Efficient Semi-Analytical Model for Composite and Sandwich Plates Subjected to Thermal Load

A simple, semi-analytical model with mixed (stresses and displacements) fundamental variables starting from the exact three dimensional (3D) governing partial differential equations (PDEs) of laminated composite and sandwich plates for thermo-mechanical stress analysis has been presented in this paper. The plate is assumed simply supported on all four edges. Two different temperature variations through the thickness of plates are considered for numerical investigation. The accuracy and the effectiveness of the proposed model are assessed by comparing numerical results from the present investigation with the available elasticity solutions. Some new results for sandwich laminates are also presented for future reference.

Orthotropic material properties of the gerbil basilar membrane

In this paper, two sets of experimental results to extract the two effective elastic moduli, the effective shear modulus, and the effective Poisson's ratio for the gerbil cochlear partition are analyzed. In order to accomplish this, a geometrically nonlinear composite orthotropic plate model is employed. The model is used to predict both out-of-plane and in-plane motion of the partition under a static finite area distributed load. This loading condition models the small, but finite size, probe tips used in experiments. Both in-plane and out-of-plane motion are needed for comparison with recent experimental results. It is shown that the spatial decay rate (the space constant) for the in-plane deflection is different than for the out-of-plane deflection, which has a significant effect on the derived partition properties. The size of the probe tip is shown to have little influence on the results. Results are presented for two types of boundary conditions. Orthotropy ratios determined from the experimental data are found to vary with longitudinal position and choice of boundary conditions. Orthotropy ratios (the ratio of the two elastic moduli) are in the range of 65 close to the base to 10 in the upper middle turn of the cochlea.