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Sample records for nonlinear laminated composite

  1. NONLINEAR THEORY OF DYNAMIC STABILITY FOR LAMINATED COMPOSITE CYLINDRICAL SHELLS

    Institute of Scientific and Technical Information of China (English)

    周承倜; 王列东

    2001-01-01

    Hamilton Principle was uaed to derive the general governing equations of nonlinear dynamic stability for laminated cylindrical shells in which, factors of nonlinear large deflection, transverse shear and longitudinal inertia force were concluded. Equations were solved by variational method. Analysis reveals that under the action of dynamic load,laminated cylindrical shells will fall into a state of parametric resonance and enter into the dynamic unstable region that causes dynamic instability of shells. Laminated shells of three typical composites were computed: i.e. T300/5 208 graphite epoxy E-glass epoxy, and ARALL shells. Results show that all factors will induce important influence for dynamic stability of laminated shells. So, in research of dynamic stability for laminated shells, to consider these factors is important.

  2. Metamodel for nonlinear dynamic response analysis of damaged laminated composites

    Directory of Open Access Journals (Sweden)

    Mahmoudi S.

    2016-01-01

    Full Text Available Damage affects negatively the safety of the structure and can lead to failure. Thus, it is recommended to use structural health monitoring techniques in order to detect, localize and quantify damage. The main aim of the current work is the development of a numerical metamodel to investigate the dynamic behavior of damaged composite structures. Hence, a metamodelling for damage prediction and dynamic behavior analysis of laminate composite structures is proposed, wherein the stress state in the structure is used as indicative parameters and artificial neural networks as a learning tool.

  3. A Novel Rational Design Method for Laminated Composite Structures Exhibiting Complex Geometrically Nonlinear Buckling Behaviour

    DEFF Research Database (Denmark)

    Lindgaard, Esben; Lund, Erik

    2012-01-01

    This paper presents a novel FEM-based approach for fiber angle optimal design of laminated composite structures exhibiting complicated nonlinear buckling behavior, thus enabling design of lighter and more cost-effective structures. The approach accounts for the geometrically nonlinear behavior...

  4. Nonlinear dynamics of angle-ply composite laminated thin plate with third-order shear deformation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An asymptotic perturbation method is presented based on the Fourier expansion and temporal rescaling to investigate the nonlinear oscillations and chaotic dynamics of a simply supported angle-ply composite laminated rectangular thin plate with parametric and external excitations.According to the Reddy’s third-order plate theory,the governing equations of motion for the angle-ply composite laminated rectangular thin plate are derived by using the Hamilton’s principle.Then,the Galerkin procedure is applied to the partial differential governing equation to obtain a two-degrees-of-freedom nonlinear system including the quadratic and cubic nonlinear terms.Such equations are utilized to deal with the resonant case of 1:1 internal resonance and primary parametric resonance-1/2 subharmonic resonance.Furthermore,the stability analysis is given for the steady-state solutions of the averaged equation.Based on the averaged equation obtained by the asymptotic perturbation method,the phase portrait and power spectrum are used to analyze the multi-pulse chaotic motions of the angle-ply composite laminated rectangular thin plate.Under certain conditions the various chaotic motions of the angle-ply composite laminated rectangular thin plate are found.

  5. A hybrid method based upon nonlinear Lamb wave response for locating a delamination in composite laminates.

    Science.gov (United States)

    Yelve, Nitesh P; Mitra, Mira; Mujumdar, P M; Ramadas, C

    2016-08-01

    A new hybrid method based upon nonlinear Lamb wave response in time and frequency domains is introduced to locate a delamination in composite laminates. In Lamb wave based nonlinear method, the presence of damage is shown by the appearance of higher harmonics in the Lamb wave response. The proposed method not only uses this spectral information but also the corresponding temporal response data, for locating the delamination. Thus, the method is termed as a hybrid method. The paper includes formulation of the method and its application to locate a Barely Visible Impact Damage (BVID) induced delamination in a Carbon Fiber Reinforced Polymer (CFRP) laminate. The method gives the damage location fairly well. It is a baseline free method, as it does not need data from the pristine specimen.

  6. Analysis of interlaminar stress and nonlinear dynamic response for composite laminated plates with interfacial damage

    Science.gov (United States)

    Zhu, F. H.; Fu, Y. M.

    2008-12-01

    By considering the effect of interfacial damage and using the variation principle, three-dimensional nonlinear dynamic governing equations of the laminated plates with interfacial damage are derived based on the general six-degrees-of-freedom plate theory towards the accurate stress analysis. The solutions of interlaminar stress and nonlinear dynamic response for a simply supported laminated plate with interfacial damage are obtained by using the finite difference method, and the results are validated by comparison with the solution of nonlinear finite element method. In numerical calculations, the effects of interfacial damage on the stress in the interface and the nonlinear dynamic response of laminated plates are discussed.

  7. Hybrid composite laminate structures

    Science.gov (United States)

    Chamis, C. C.; Lark, R. F. (Inventor)

    1977-01-01

    An invention which relates to laminate structures and specifically to essentially anisotropic fiber composite laminates is described. Metal foils are selectively disposed within the laminate to produce increased resistance to high velocity impact, fracture, surface erosion, and other stresses within the laminate.

  8. Analysis of interlaminar stress and nonlinear dynamic response for composite laminated plates with interfacial damage

    Institute of Scientific and Technical Information of China (English)

    F. H. Zhu; Y. M. Fu

    2008-01-01

    By considering the effect of interfacial damage and using the variation principle, three-dimensional nonli-near dynamic governing equations of the laminated plates with interfacial damage are derived based on the general six-degrees-of-freedom plate theory towards the accurate stress analysis. The solutions of interlaminar stress and nonlinear dynamic response for a simply supported laminated plate with interfacial damage are obtained by using the finite dif-ference method, and the results are validated by compari-son with the solution of nonlinear finite element method. In numerical calculations, the effects of interfacial damage on the stress in the interface and the nonlinear dynamic response of laminated plates are discussed.

  9. Modeling the macroscopic behavior of two-phase nonlinear composites by infinite-rank laminates

    Science.gov (United States)

    Idiart, Martín I.

    A new approach is proposed for estimating the macroscopic behavior of two-phase nonlinear composites with random, particulate microstructures. The central idea is to model composites by sequentially laminated constructions of infinite rank whose macroscopic behavior can be determined exactly. The resulting estimates incorporate microstructural information up to the two-point correlation functions, and require the solution to a Hamilton-Jacobi equation with the inclusion concentration and the macroscopic fields playing the role of 'time' and 'spatial' variables, respectively. Because they are realizable, by construction, these estimates are guaranteed to be convex, to satisfy all pertinent bounds, to exhibit no duality gap, and to be exact to second order in the heterogeneity contrast. Sample results are provided for two- and three-dimensional power-law composites, and are compared with other homogenization estimates, as well as with numerical simulations available from the literature. The estimates are found to give physically sensible predictions for all the cases considered, even for extreme values of the nonlinearity and heterogeneity contrast. Interestingly, in the case of isotropic porous materials under hydrostatic loadings, the estimates agree exactly with standard Gurson-type models for viscoplastic porous media.

  10. An analytical nonlinear model for laminate multiferroic composites reproducing the DC magnetic bias dependent magnetoelectric properties.

    Science.gov (United States)

    Lin, Lizhi; Wan, Yongping; Li, Faxin

    2012-07-01

    In this work, we propose an analytical nonlinear model for laminate multiferroic composites in which the magnetic-field-induced strain in magnetostrictive phase is described by a standard square law taking the stress effect into account, whereas the ferroelectric phase retains a linear piezoelectric response. Furthermore, differing from previous models which assume uniform deformation, we take into account the stress attenuation and adopt non-uniform deformation along the layer thickness in both piezoelectric and magnetostrictive phases. Analysis of this model on L-T and L-L modes of sandwiched Terfenol-D/lead zirconate titanate/Terfenol-D composites can well reproduce the observed dc magnetic field (H(dc)) dependent magnetoelectric coefficients, which reach their maximum with the H(dc) all at about 500 Oe. The model also suggests that stress attenuation along the layer thickness in practical composites should be taken into account. Furthermore, the model also indicates that a high volume fraction of magnetostrictive phase is required to get giant magnetoelectric coupling, coinciding with existing models.

  11. Stochastic analysis of laminated composite plates on elastic foundation: The cases of post-buckling behavior and nonlinear free vibration

    Energy Technology Data Exchange (ETDEWEB)

    Singh, B.N., E-mail: bnsingh@aero.iitkgp.ernet.i [Department of Aerospace Engineering, IIT Kharagpur 721 302, West Bengal (India); Lal, Achchhe [Department of Mechanical Engineering, SVNIT, Surat 395007 (India)

    2010-10-15

    This study deals with the stochastic post-buckling and nonlinear free vibration analysis of a laminated composite plate resting on a two parameters Pasternak foundation with Winkler cubic nonlinearity having uncertain system properties. The system properties are modeled as basic random variables. A C{sup 0} nonlinear finite element formulation of the random problem based on higher-order shear deformation theory in the von Karman sense is presented. A direct iterative method in conjunction with a stochastic nonlinear finite element method proposed earlier by the authors is extended to analyze the effect of uncertainty in system properties on the post-buckling and nonlinear free vibration of the composite plates having Winler type of geometric nonlinearity. Mean as well as standard deviation of the responses have been obtained for various combinations of geometric parameters, foundation parameters, stacking sequences and boundary conditions and compared with those available in the literature and Monte Carlo simulation.

  12. Stability of laminated composites

    Energy Technology Data Exchange (ETDEWEB)

    Guz`, A.N.; Chekhov, V.N. [Inst. of Mechanics of the Academy of Sciences of the Ukrainian, Kiev (Ukraine)

    1992-02-01

    The characteristic special feature of deformation behavior of modern laminated composite materials and structural elements fabricated from these materials, at current levels of loading and operating conditions is the occurrence of the purely three-dimensional stress-deformed state. In this process some specific mechanical phenomena and effects may occur, which is impossible to describe within the framework of applied or approximate approaches existing currently in deformable solid body mechanics. The structure of massive laminated materials may be included in this class of phenomena when the critical parameters of the problem depend only on the ratio between mechanical and geometrical characteristics of single layers and are independent of the dimensions and the form of the total laminated body as a whole. Since this phenomenon may be the beginning of the process of fracture of these materials, and the loss of the load-carrying capacity of structure elements fabricated from them, we consider below, in three-dimensional formulation, the problem of the surface and internal instability in laminated composite materials under compressive surface loads. The classification of the existing types of stability problems is presented for laminated materials and approaches for their solution presented in the literature. On the basis of three-dimensional linearized stability theory, within the framework of the piecewise-homogeneous media model, the general formulation of the most characteristic classes of stability problems of laminated materials is given in Langrangian coordinates at small and finite, homogeneous and inhomogeneous precritical deformation. Analytic and variational methods of investigation of formulated problems are given with application to various models of laminated bodies models, in accordance with accepted stability criteria. The accuracy of these models is evaluated, based on th example of the solution of certain model problems.

  13. Geometrically nonlinear behavior of piezoelectric laminated plates

    Science.gov (United States)

    Rabinovitch, Oded

    2005-08-01

    The geometrically nonlinear behavior of piezo-laminated plates actuated with isotropic or anisotropic piezoelectric layers is analytically investigated. The analytical model is derived using the variational principle of virtual work along with the lamination and plate theories, the von Karman large displacement and moderate rotation kinematic relations, and the anisotropic piezoelectric constitutive laws. A solution strategy that combines the approach of the method of lines, the advantages of the finite element concept, and the variational formulation is developed. This approach yields a set of nonlinear ordinary differential equations with nonlinear boundary conditions, which are solved using the multiple-shooting method. Convergence and verification of the model are examined through comparison with linear and nonlinear results of other approximation methods. The nonlinear response of two active plate structures is investigated numerically. The first plate is actuated in bending using monolithic piezoceramic layers and the second one is actuated in twist using macro-fiber composites. The results quantitatively reveal the complicated in-plane stress state associated with the piezoelectric actuation and the geometrically nonlinear coupling of the in-plane and out-of-plane responses of the plate. The influence of the nonlinear effects ranges from significant stiffening in certain combinations of electrical loads and boundary conditions to amplifications of the induced deflections in others. The paper closes with a summary and conclusions.

  14. Nonlinear dynamic response analysis of localized damaged laminated composite structures in the context of component mode synthesis

    Science.gov (United States)

    Mahmoudi, S.; Trivaudey, F.; Bouhaddi, N.

    2015-07-01

    The aim of this study is the prediction of the dynamic response of damaged laminated composite structures in the context of component mode synthesis. Hence, a method of damage localization of complex structures is proposed. The dynamic behavior of transversely isotropic layers is expressed through elasticity coupled with damage based on an existing macro model for cracked structures. The damage is located only in some regions of the whole structure, which is decomposed on substructures. The incremental linear dynamic governing equations are obtained by using the classical linear Kirchhoff-Love theory of plates. Then, considering the damage-induced nonlinearity, the obtained nonlinear dynamic equations are solved in time domain. However, a detailed finite element modelling of such structure on the scale of localized damage would generate very high computational costs. To reduce this cost, Component Mode Synthesis method (CMS) is used for modelling a nonlinear fine-scale substructure damaged, connected to linear dynamic models of the remaining substructures, which can be condensed and not updated at each iteration. Numerical results show that the mechanical properties of the structure highly change when damage is taken into account. Under an impact load, damage increases and reaches its highest value with the maximum of the applied load and then remains unchanged. Besides, the eigenfrequencies of the damaged structure decrease comparing with those of an undamaged one. This methodology can be used for monitoring strategies and lifetime estimations of hybrid complex structures due to the damage state is known in space and time.

  15. Optimization of composite laminates

    Science.gov (United States)

    Gurdal, Zafer; Haftka, Raphael T.

    Design of composite structures can be viewed as a multi-faceted task, one which requires integration of issues related to composite mechanics, structural analysis, optimization, and manufacturing. The major coverage of the paper is on the issue of optimization, with special emphasis on the use of optimization for designing with discrete and integer valued variables required for the stacking-sequence optimization. Different techniques that can be used for stacking sequence optimization are introduced, and different aspects of their application are demonstrated for laminate buckling optimization.

  16. Optimization of Laminated Composite Structures

    DEFF Research Database (Denmark)

    Henrichsen, Søren Randrup

    Laminated composite materials are widely used in the design of light weight high performance structures like wind turbine blades and aeroplanes due to their superior stiffness and strength-to-weight-ratios compared to their metal counter parts. Furthermore, the use of laminated composite materials...... allows for a higher degree of tailoring of the resulting material. To enable better utilization of the composite materials, optimum design procedures can be used to assist the engineer. This PhD thesis is focused on developing numerical methods for optimization of laminated composite structures....... The first part of the thesis is intended as an aid to read the included papers. Initially the field of research is introduced and the performed research is motivated. Secondly, the state-of-the-art is reviewed. The review includes parameterizations of the constitutive properties, linear and geometrically...

  17. Finite elements modeling of delaminations in composite laminates

    DEFF Research Database (Denmark)

    Gaiotti, m.; Rizzo, C.M.; Branner, Kim;

    2011-01-01

    The application of composite materials in many structures poses to engineers the problem to create reliable and relatively simple methods, able to estimate the strength of multilayer composite structures. Multilayer composites, like other laminated materials, suffer from layer separation, i.e., d...... by finite elements using different techniques. Results obtained with different finite element models are compared and discussed.......The application of composite materials in many structures poses to engineers the problem to create reliable and relatively simple methods, able to estimate the strength of multilayer composite structures. Multilayer composites, like other laminated materials, suffer from layer separation, i...... of the buckling strength of composite laminates containing delaminations. Namely, non-linear buckling and post-buckling analyses are carried out to predict the critical buckling load of elementary composite laminates affected by rectangular delaminations of different sizes and locations, which are modelled...

  18. LARGE AMPLITUDE FREE VIBRATIONS OF LAMINATED COMPOSITE PLATES

    Institute of Scientific and Technical Information of China (English)

    Wang Haowen; Gao Zheng; Zheng Zhaochang

    2000-01-01

    This paper deals with large amplitude free flexural vibrations of laminated composite plates using a 9-node Heterosis degenerated isoparametric quadrilateral element, including the effects of transverse shear and rotary inertia. The nonlinear dynamic equations of the plates are formulated in von Karman's sense. Amplitude-frequemcy relationships are obtained through dynamic response history using the Newmark numerical integration scheme. Detailed numerical results based on various parameters are presented for orthotropic laminated plates with different boundary conditions. The rectangular anti-symmetric cross-ply plates show the softening type of nonlinearity for initial small amplitudes. The displacement amplitudes decrease and nonlinear frequencies increase with the increment of time.

  19. Nonlinear sequential laminates reproducing hollow sphere assemblages

    Science.gov (United States)

    Idiart, Martín I.

    2007-07-01

    A special class of nonlinear porous materials with isotropic 'sequentially laminated' microstructures is found to reproduce exactly the hydrostatic behavior of 'hollow sphere assemblages'. It is then argued that this result supports the conjecture that Gurson's approximate criterion for plastic porous materials, and its viscoplastic extension of Leblond et al. (1994), may actually yield rigorous upper bounds for the hydrostatic flow stress of porous materials containing an isotropic, but otherwise arbitrary, distribution of porosity. To cite this article: M.I. Idiart, C. R. Mecanique 335 (2007).

  20. Meshfree modeling in laminated composites

    KAUST Repository

    Simkins, Daniel Craig

    2012-09-27

    A problem of increasing importance in the aerospace industry is in detailed modeling of explicit fracture in laminated composite materials. For design applications, the simulation must be capable of initiation and propagation of changes in the problem domain. Further, these changes must be able to be incorporated within a design-scale simulation. The use of a visibility condition, coupled with the local and dynamic nature of meshfree shape function construction allows one to initiate and explicitly open and propagate holes inside a previously continuous problem domain. The method to be presented naturally couples to a hierarchical multi-scale material model incorporating external knowldege bases to achieve the goal of a practical explicit fracture modeling capability for full-scale problems. © 2013 Springer-Verlag.

  1. Morphing of Bistable Composite Laminates Using Distributed Piezoelectric Actuators

    Directory of Open Access Journals (Sweden)

    Marie-Laure Dano

    2012-01-01

    Full Text Available The use of bistable unsymmetric cross-ply laminates for morphing application has received growing attention in the last few years. So far, most studies use large rectangular piezoelectric Macro Fiber Composite (MFC patches bonded at the center of the laminate to induce snap-through. However, the use of large rectangular MFC patches bonded in the center of the laminates significantly influences the shape of the laminate by greatly reducing the curvature at the midsection of the laminate where the MFC patches are bonded. This paper presents a study where narrow cocured MFC strips distributed over the entire surface are used to induce snap-through of unsymmetric cross-ply laminates. This MFC configuration allows having a more uniform curvature in the laminate. Since the strips are bonded on both sides, reverse snap-through should be obtained. The study was both theoretical and experimental. A finite element nonlinear analysis was used to predict the two stable cylindrical configurations and the snap-through induced by MFC actuation. For the experimental study, a laminate-MFC structure was manufactured and tested. The shapes were measured using a 3D image correlation system as a function of applied voltage. Good correlations for the cylindrical shape and displacement field were observed.

  2. Application of the R-Functions Theory to Problems of Nonlinear Dynamics of Laminated Composite Shallow Shells and Plates: Review

    OpenAIRE

    2016-01-01

    A review of studies performed using the R-functions theory to solve problems of nonlinear dynamics of plates and shallow shells is presented. The systematization of results and studies for the problems of free and parametric vibrations and for problems of static and dynamic stability is fulfilled. Expansion of the developed original method of discretization for nonlinear movement equations on new classes of nonlinear problems is shown. These problems include researches of vibratio...

  3. Scarf Repair of Composite Laminates

    Directory of Open Access Journals (Sweden)

    Xie Zonghong

    2016-01-01

    Full Text Available The use of composite materials, such as carbon-fiber reinforced plastic (CFRP composites, aero-structures has led to an increased need of advanced assembly joining and repair technologies. Adhesive bonded repairs as an alternative to recover full or part of initial strength were investigated. Tests were conducted with the objective of evaluating the effectiveness of techniques used for repairing damage fiber reinforced laminated composites. Failure loads and failure modes were generated and compared with the following parameters: scarf angles, roughness of grind tool and number of external plies. Results showed that scarf angle was the critical parameter and the largest tensile strength was observed with the smallest scarf angle. Besides, the use of external plies at the outer surface could not increase the repairs efficiency for large scarf angle. Preparing the repair surfaces by sanding them with a sander ranging from 60 to 100 grit number had significant effect on the failure load. These results allowed the proposal of design principles for repairing CFRP structures.

  4. Direct Composite Laminate Veneers: Three Case Reports

    Directory of Open Access Journals (Sweden)

    Bora Korkut

    2013-05-01

    Full Text Available Re-establishing a patient’s lost dental esthetic appearance is one of the most important topics for contemporary dentistry. New treatment materials and methods have been coming on the scene, day by day, in order to achieve such an aim. Most dentists prefer more conservative and aesthetic approaches, such as direct and indirect laminate veneer restorations, instead of full-ceramic crowns for anteriors where aesthetics is really important. Laminate veneers are restorations which are envisioned to correct existing abnormalities, esthetic deficiencies and discolorations. Laminate veneer restorations may be processed in two different ways: direct or indirect. Direct laminate veneers have no need to be prepared in the laboratory and are based on the principle of application of a composite material directly to the prepared tooth surface in the dental clinic. Indirect laminate veneers may be produced from composite materials or ceramics, which are cemented to the tooth with an adhesive resin. In this case report, direct composite laminate veneer technique used for three patients with esthetic problems related to fractures, discolorations and an old prolapsed restoration, is described and six-month follow-ups are discussed. As a conclusion, direct laminate veneer restorations may be a treatment option for patients with the esthetic problems of anterior teeth in cases similar to those reported here.

  5. Direct composite laminate veneers: three case reports.

    Science.gov (United States)

    Korkut, Bora; Yanıkoğlu, Funda; Günday, Mahir

    2013-01-01

    Re-establishing a patient's lost dental esthetic appearance is one of the most important topics for contemporary dentistry. New treatment materials and methods have been coming on the scene, day by day, in order to achieve such an aim. Most dentists prefer more conservative and aesthetic approaches, such as direct and indirect laminate veneer restorations, instead of full-ceramic crowns for anteriors where aesthetics is really important. Laminate veneers are restorations which are envisioned to correct existing abnormalities, esthetic deficiencies and discolo-rations. Laminate veneer restorations may be processed in two different ways: direct or indirect. Direct laminate veneers have no need to be prepared in the laboratory and are based on the principle of application of a composite material directly to the prepared tooth surface in the dental clinic. Indirect laminate veneers may be produced from composite materials or ceramics, which are cemented to the tooth with an adhesive resin. In this case report, direct composite laminate veneer technique used for three patients with esthetic problems related to fractures, discolorations and an old prolapsed restoration, is described and six-month follow-ups are discussed. As a conclusion, direct laminate veneer restorations may be a treatment option for patients with the esthetic problems of anterior teeth in cases similar to those reported here.

  6. Mechanical behaviors of notched composite laminates

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Presents the study on the mechanical behaviors of composite laminates with both static and fatigue tests per formed with different notched specimens and concludes with experimental results that ultimate strength and initial stiff ness of various notched composite laminates is almost as same as un-notched ones but the fatigue life of notched speci mens is much higher than un-notched ones. Compared with metals, composite materials are notch insensitive. The properties measured by using bar type specimens can not represent the real properties of composite laminates. Notches on the free edge may be helpful to the structure. The fatigue life can be predicted through theoretical models estab lished using the residual stiffness model.

  7. Multifunctional Laminated Composite Materials for Protective Clothing

    Directory of Open Access Journals (Sweden)

    Nermin M. Aly

    2014-10-01

    Full Text Available Protective clothing performs a vital role in maintaining the safety of human in workplace. The developments in this field are proceeding to fulfill the needs with multifunctional materials at competitive costs. Recently, the protective clothing field introduces the usage of composite materials taking advantage of their outstanding properties. In this paper, the multifunctional performance of hybrid laminated composites (HLC was investigated aiming to be utilized in protective clothing. The influences of reinforcement and resin properties on the physical properties of the laminated composites and their resistance to puncture load and UV transmittance were studied. ANOVA test was used for the statistical analysis of the results. The results showed that, the reinforcement material and structure and the fiber/matrix interface have major influences on the laminated composites performance. It was revealed that, the HLC fabricated from (polyester/glass fabric with satin 4 structure and nonwoven glass fiber mat exhibited the best functional performance.

  8. Free edge effects in laminated composites

    Science.gov (United States)

    Herakovich, C. T.

    1989-01-01

    The fundamental mechanics of free-edge effects in laminated fiber-reinforced composites is examined, reviewing the results of recent experimental and analytical investigations. The derivation of the governing equations for the basic problem is outlined, including the equilibrium and mismatch conditions and the elasticity formulation, and experimental data on axial displacement and shear strain in angle-ply laminates are summarized. Numerical predictions of free-edge deformation and interlaminar and through-thickness stress distributions are presented for cross-ply, angle-ply, and quasi-isotropic laminates, and the mechanisms of edge damage and failure in angle-ply laminates are briefly characterized. Extensive diagrams, drawings, graphs, and photographs are provided.

  9. Lamb Wave Propagation in Laminated Composite Structures

    OpenAIRE

    Gopalakrishnan, S.

    2013-01-01

    Damage detection using guided Lamb waves is an important tool in Structural health Monitoring. In this paper, we outline a method of obtaining Lamb wave modes in composite structures using two dimensional Spectral Finite Elements. Using this approach, Lamb wave dispersion curves are obtained for laminated composite structures with different fibre orientation. These propagating Lamb wave modes are pictorially captured using tone burst signal.

  10. A stable numerical solution method in-plane loading of nonlinear viscoelastic laminated orthotropic materials

    Science.gov (United States)

    Gramoll, K. C.; Dillard, D. A.; Brinson, H. F.

    1989-01-01

    In response to the tremendous growth in the development of advanced materials, such as fiber-reinforced plastic (FRP) composite materials, a new numerical method is developed to analyze and predict the time-dependent properties of these materials. Basic concepts in viscoelasticity, laminated composites, and previous viscoelastic numerical methods are presented. A stable numerical method, called the nonlinear differential equation method (NDEM), is developed to calculate the in-plane stresses and strains over any time period for a general laminate constructed from nonlinear viscoelastic orthotropic plies. The method is implemented in an in-plane stress analysis computer program, called VCAP, to demonstrate its usefulness and to verify its accuracy. A number of actual experimental test results performed on Kevlar/epoxy composite laminates are compared to predictions calculated from the numerical method.

  11. ROBUST OPTIMUM DESIGN OF LAMINATED COMPOSITE PLATES

    Institute of Scientific and Technical Information of China (English)

    WangXiangyang; ChenJianqiao

    2004-01-01

    A last-ply failure (LPF) analysis method for laminated composite plates is incorporated into the finite element code-ANSYS, and a robust optimum design method is presented. The composite structure is analyzed by considering both in-plane and out-of-plane loads. For a lamina,two major failure modes are considered: matrix failure and fiber breakage that axe characterized by the proper strength criteria in the literature. When a lamina has failed, the laminate stiffness is modified to reflect the damage, and stresses in the structure are re-analyzed. This procedure is repeatedly performed until the whole structure fails and thus the ultimate strength is determined.A structural optimization problem is solved with the fiber orientation and the lamina thickness as the design variables and the LPF load as the objective. Finally, the robust optimum design method for laminates is presented and discussed.

  12. Continuous jute fibre reinforced laminated paper composite and reinforcement-fibre free paper laminate

    Indian Academy of Sciences (India)

    B B Verma

    2009-12-01

    Plastic bags create a serious environmental problem. The proposed jute fibre reinforced laminated paper composite and reinforcement-fibre free paper laminate may help to combat the war against this pollutant to certain extent. The paper laminate, without reinforcement fibre, exhibited a few fold superiority in tensile properties than single paper strip. The studies further show that an appreciable improvement in tensile properties can be achieved by introducing continuous jute fibre in paper laminates.

  13. Methods for Preparing Nanoparticle-Containing Thermoplastic Composite Laminates

    Science.gov (United States)

    Gruber, Mark B. (Inventor); Jensen, Brian J. (Inventor); Cano, Roberto J. (Inventor)

    2016-01-01

    High quality thermoplastic composites and composite laminates containing nanoparticles and/or nanofibers, and methods of producing such composites and laminates are disclosed. The composites comprise a thermoplastic polymer and a plurality of nanoparticles, and may include a fibrous structural reinforcement. The composite laminates are formed from a plurality of nanoparticle-containing composite layers and may be fused to one another via an automated process.

  14. Progressive delamination in polymer matrix composite laminates: A new approach

    Science.gov (United States)

    Chamis, C. C.; Murthy, P. L. N.; Minnetyan, L.

    1992-01-01

    A new approach independent of stress intensity factors and fracture toughness parameters has been developed and is described for the computational simulation of progressive delamination in polymer matrix composite laminates. The damage stages are quantified based on physics via composite mechanics while the degradation of the laminate behavior is quantified via the finite element method. The approach accounts for all types of composite behavior, laminate configuration, load conditions, and delamination processes starting from damage initiation, to unstable propagation, and to laminate fracture. Results of laminate fracture in composite beams, panels, plates, and shells are presented to demonstrate the effectiveness and versatility of this new approach.

  15. Identification Techniques in Composite Laminates

    DEFF Research Database (Denmark)

    Pedersen, Pauli

    1999-01-01

    Combined experimental-numerical methods are presented with the goal of obtaining material stiffness for composite materials. The identification is based on eigenfrequencies for a free rectangular plate, because excellent agreement between measured and calculated eigenfrequencies can be obtained...

  16. Response of composite laminates on impact of high velocity projectiles

    Energy Technology Data Exchange (ETDEWEB)

    Siva Kumar, K.; Balakrishna Bhat, T. [Defence Metallurgical Research Lab., Hyderabad (India)

    1998-05-01

    Past work on damage of composites subjected to low velocity and hypervelocity impact has been briefly reviewed and some new results on the glass fibre reinforced plastic composite laminates impacted with high velocity projectiles are presented. The effect of thickness of the laminates and the angle of attack on the energy absorption by the composite laminates and the area of damage caused by impact are described. A correlation is made between the energy absorption and the area of damage. Also described is a new method called infiltration radiography useful for assessing the damage in laminated composites upon ballistic impact. (orig.) 28 refs.

  17. Thermoelastic wave propagation in laminated composites plates

    Directory of Open Access Journals (Sweden)

    Verma K. L.

    2012-12-01

    Full Text Available The dispersion of thermoelastic waves propagation in an arbitrary direction in laminated composites plates is studied in the framework of generalized thermoelasticity in this article. Three dimensional field equations of thermoelasticity with relaxation times are considered. Characteristic equation is obtained on employing the continuity of displacements, temperature, stresses and thermal gradient at the layers’ interfaces. Some important particular cases such as of free waves on reducing plates to single layer and the surface waves when thickness tends to infinity are also discussed. Uncoupled and coupled thermoelasticity are the particular cases of the obtained results. Numerical results are also obtained and represented graphically.

  18. Laminated composites modeling in ADAGIO/PRESTO.

    Energy Technology Data Exchange (ETDEWEB)

    Hammerand, Daniel Carl

    2004-05-01

    A linear elastic constitutive equation for modeling fiber-reinforced laminated composites via shell elements is specified. The effects of transverse shear are included using first-order shear deformation theory. The proposed model is written in a rate form for numerical evaluation in the Sandia quasi-statics code ADAGIO and explicit dynamics code PRESTO. The equation for the critical time step needed for explicit dynamics is listed assuming that a flat bilinear Mindlin shell element is used in the finite element representation. Details of the finite element implementation and usage are given. Finally, some of the verification examples that have been included in the ADAGIO regression test suite are presented.

  19. Delamination tolerance studies in laminated composite panels

    Indian Academy of Sciences (India)

    K L Singh; B Dattaguru; T S Ramamurthy; P D Mangalgiri

    2000-08-01

    Determination of levels of tolerance in delaminated composite panels is an important issue in composite structures technology. The primary intention is to analyse delaminated composite panels and estimate Strain Energy Release Rate (SERR) parameters at the delamination front to feed into acceptability criteria. Large deformation analysis is necessary to cater for excessive rotational deformations in the delaminated sublaminate. Modified Virtual Crack Closure Integral (MVCCI) is used to estimate all the three SERR components at the delamination front from the finite element output containing displacements, strains and stresses. The applied loading conditions are particularly critical and compressive loading on the panel could lead to buckling of the delaminated sublaminate and consequent growth of delamination. Numerical results are presented for circular delamination of varioussizes and delamination at various interfaces (varying depth-wise location) between the base- and the sub-laminates. Numerical data are also presented on the effect of bi-axial loading and in particular on compressive loading in both directions. The results can be used to estimate delamination tolerance at various depths (or at various interfaces) in the laminate.

  20. Stochastic analysis of laminated composite plate considering stochastic homogenization problem

    Institute of Scientific and Technical Information of China (English)

    S. SAKATA; K. OKUDA; K. IKEDA

    2015-01-01

    This paper discusses a multiscale stochastic analysis of a laminated composite plate consisting of unidirectional fiber reinforced composite laminae. In particular, influence of a microscopic random variation of the elastic properties of component materials on mechanical properties of the laminated plate is investigated. Laminated composites are widely used in civil engineering, and therefore multiscale stochastic analysis of laminated composites should be performed for reliability evaluation of a composite civil structure. This study deals with the stochastic response of a laminated composite plate against the microscopic random variation in addition to a random variation of fiber orientation in each lamina, and stochastic properties of the mechanical responses of the laminated plate is investigated. Halpin-Tsai formula and the homogenization theory-based finite element analysis are employed for estimation of effective elastic properties of lamina, and the classical laminate theory is employed for analysis of a laminated plate. The Monte-Carlo simulation and the first-order second moment method with sensitivity analysis are employed for the stochastic analysis. From the numerical results, importance of the multiscale stochastic analysis for reliability evaluation of a laminated composite structure and applicability of the sensitivity-based approach are discussed.

  1. Higher-dimensional chaotic dynamics of a composite laminated piezoelectric rectangular plate

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; GAO MeiJuan; YAO MingHui; YAO ZhiGang

    2009-01-01

    The analysis on the chaotic dynamics of a six-dimensional nonlinear system which represents the averaged equation of a composite laminated piezoelectric rectangular plate is given for the first time. The theory of normal form and the energy-phase method are combined to investigate the higher-dimensional chaotic dynamics of the composite laminated piezoelectric rectangular plate. Firstly, the theory of normal form is used to reduce the six-dimensional averaged equation to the simpler normal form.Then, the energy-phase method is extended to analyze the global bifurcations and chaotic dynamics of a six-dimensional nonlinear system. The analysis results indicate that there exist the homoclinic bifurcation and Shilnikov type multi-pulse chaos for the composite laminated piezoelectric rectangular plate. Finally, numerical simulations are also used to investigate the nonlinear dynamic characteristics of the composite laminated piezoelectric rectangular plate. The results of numerical simulations also demonstrate that there exist the chaotic motions and the multi-pulse jumping orbits of the composite laminated piezoelectric rectangular plate.

  2. Higher-dimensional chaotic dynamics of a composite laminated piezoelectric rectangular plate

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The analysis on the chaotic dynamics of a six-dimensional nonlinear system which represents the averaged equation of a composite laminated piezoelectric rectangular plate is given for the first time. The theory of normal form and the energy-phase method are combined to investigate the higher-dimen-sional chaotic dynamics of the composite laminated piezoelectric rectangular plate. Firstly,the theory of normal form is used to reduce the six-dimensional averaged equation to the simpler normal form. Then,the energy-phase method is extended to analyze the global bifurcations and chaotic dynamics of a six-dimensional nonlinear system. The analysis results indicate that there exist the homoclinic bi-furcation and Shilnikov type multi-pulse chaos for the composite laminated piezoelectric rectangular plate. Finally,numerical simulations are also used to investigate the nonlinear dynamic characteristics of the composite laminated piezoelectric rectangular plate. The results of numerical simulations also demonstrate that there exist the chaotic motions and the multi-pulse jumping orbits of the composite laminated piezoelectric rectangular plate.

  3. BILAM: a composite laminate failure-analysis code using bilinear stress-strain approximations

    Energy Technology Data Exchange (ETDEWEB)

    McLaughlin, P.V. Jr.; Dasgupta, A.; Chun, Y.W.

    1980-10-01

    The BILAM code which uses constant strain laminate analysis to generate in-plane load/deformation or stress/strain history of composite laminates to the point of laminate failure is described. The program uses bilinear stress-strain curves to model layer stress-strain behavior. Composite laminates are used for flywheels. The use of this computer code will help to develop data on the behavior of fiber composite materials which can be used by flywheel designers. In this program the stress-strain curves are modelled by assuming linear response in axial tension while using bilinear approximations (2 linear segments) for stress-strain response to axial compressive, transverse tensile, transverse compressive and axial shear loadings. It should be noted that the program attempts to empirically simulate the effects of the phenomena which cause nonlinear stress-strain behavior, instead of mathematically modelling the micromechanics involved. This code, therefore, performs a bilinear laminate analysis, and, in conjunction with several user-defined failure interaction criteria, is designed to provide sequential information on all layer failures up to and including the first fiber failure. The modus operandi is described. Code BILAM can be used to: predict the load-deformation/stress-strain behavior of a composite laminate subjected to a given combination of in-plane loads, and make analytical predictions of laminate strength.

  4. Nonlinear active control of damaged piezoelectric smart laminated plates and damage detection

    Institute of Scientific and Technical Information of China (English)

    Fu Yi-ming; RUAN Jian-li

    2008-01-01

    Considering mass and stiffness of piezoelectric layers and damage effects of composite layers,nonlinear dynamic equations of damaged piezoelectric smart laminated plates are derived.The derivation is based on the Hamilton's principle,the higherorder shear deformation plate theory, von Karman type geometrically nonlinear straindisplacement relations,and the strain energy equivalence theory.A negative velocity feedback control algorithm coupling the direct and converse piezoelectric effects is used to realize the active control and damage detection with a closed control loop. Simply supported rectangular laminated plates with immovable edges are used in numerical computation.Influence of the piezoelectric layers'location on the vibration control is investigated.In addition,effects of the degree and location of damage on the sensor output voltage are discussed.A method for damage detection is introduced.

  5. Structural Intensity Characterization of Composite Laminates Subjected to Impact Load

    Institute of Scientific and Technical Information of China (English)

    WANG Dong-fang; HE Peng-fei; LIU Zi-shun

    2008-01-01

    Structural intensity (SI) characterization of composite laminates subjected to impact load was dis-cussed. The SI pattern of the laminates which have different fiber orientations and boundary conditions wasanalyzed. The resultant forces and velocities of the laminates were calculated, and the structural intensity wasevaluated. The SI streamlines of carbon fiber reinforced epoxy composite laminates and the steel plates werediscussed. The results show that the SI streamlines of the graphite/epoxy laminates are different from that ofthe steel plates, and the SI streamlines are influenced by the boundaries, the stacking sequence of the compositelaminates. The change of the historical central displacement of the graphite/epoxy laminates is fasten thanthat of the steel plates.

  6. Effect of laminate edge conditions on the formation of microvoids in composite laminates

    Science.gov (United States)

    Anderson, J. P.; Altan, M. C.

    2015-05-01

    Manufacturing defects such as microvoids are common in thermoset composite components and are known to negatively affect their strength. The resin pressure developed in and the resin flow out from the laminates during cure have been reported to be the primary factors influencing the final void content of a composite component. In this work, the effect of laminate edge conditions during the cure process on the formation of microvoids was experimentally investigated. This was achieved by fabricating eight-ply laminates from TenCate® BT250/7781 prepreg in a hot-press at a constant cure pressure of 170 kPa while limiting the laminate perimeter available for resin flow by 0%, 25%, 50%, 75%, and 100%. The individual plies of these five laminates were conditioned at 99% relative humidity before curing to maximize the moisture present in the lay-up before fabrication. The presence of moisture in the lay-ups was expected to promote void formation and allow the effect of restricting flow at the edges of a laminate to be better identified. The restriction of resin outflow was found to cause the average characteristic void diameter to decrease by 17% and void content to rise by 33%. This phenomenon was identified to be a result of the outflow restriction increasing the number of voids trapped within the laminate and indicates that for laminates cured at low pressures resin outflow is the dominant mechanism for void reduction.

  7. A Study of Failure Strength for Fiber-Reinforced Composite Laminates with Consideration of Interface

    Directory of Open Access Journals (Sweden)

    Junjie Ye

    2015-01-01

    Full Text Available Composite laminates can exhibit the nonlinear properties due to the fiber/matrix interface debonding and matrix plastic deformation. In this paper, by incorporating the interface stress-displacement relations between fibers and matrix, as well as the viscoplastic constitutive model for describing plastic behaviors of matrix materials, a micromechanical model is used to investigate the failure strength of the composites with imperfect interface bonding. Meanwhile, the classic laminate theory, which provides the relation between micro- and macroscale responses for composite laminates, is employed. Theory results show good consistency with the experimental data under unidirectional tensile conditions at both 23°C and 650°C. On this basis, the interface debonding influences on the failure strength of the [0/90]s and [0/±45/90]s composite laminates are studied. The numerical results show that all of the unidirectional (UD laminates with imperfect interface bonding provide a sharp decrease in failure strength in the σxx-σyy plane at 23°C. However, the decreasing is restricted in some specific region. In addition, for [0/90]s and [0/±45/90]s composite laminates, the debonding interface influences on the failure envelope can be ignored when the working temperature is increased to 650°C.

  8. Reliability analysis of ceramic matrix composite laminates

    Science.gov (United States)

    Thomas, David J.; Wetherhold, Robert C.

    1991-01-01

    At a macroscopic level, a composite lamina may be considered as a homogeneous orthotropic solid whose directional strengths are random variables. Incorporation of these random variable strengths into failure models, either interactive or non-interactive, allows for the evaluation of the lamina reliability under a given stress state. Using a non-interactive criterion for demonstration purposes, laminate reliabilities are calculated assuming previously established load sharing rules for the redistribution of load as the failure of laminae occur. The matrix cracking predicted by ACK theory is modeled to allow a loss of stiffness in the fiber direction. The subsequent failure in the fiber direction is controlled by a modified bundle theory. Results using this modified bundle model are compared with previous models which did not permit separate consideration of matrix cracking, as well as to results obtained from experimental data.

  9. Penetration of Projectiles in Composite Laminates

    Directory of Open Access Journals (Sweden)

    B. P. Patel

    2004-04-01

    Full Text Available This paper deals with the prediction of the penetration phenomenon of a cylindro-conical impactor on the ke;labepoxy-laminated composites using C eight-nded serendipity q&drilateral finite elementbased on first-order shear deformation theory (FSDT. Local as well as global deformations during impact is considered in the evaluation of indentation, penetration, and perforation phases. Local strainsduring impact have been evaluated using the hypothesis made from the available experimental observations of bulging during penetration. A detailed parametric study, considering various projectilesand target plate variables, has been carried out to find their effect on the response of the plate, and ballistic parameters, such as ballistic limit and absorbed energy.

  10. Bayesian inference model for fatigue life of laminated composites

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Kiureghian, Armen Der; Berggreen, Christian

    2016-01-01

    A probabilistic model for estimating the fatigue life of laminated composite plates is developed. The model is based on lamina-level input data, making it possible to predict fatigue properties for a wide range of laminate configurations. Model parameters are estimated by Bayesian inference...

  11. Estimation of the Residual Fatigue Life of Laminated Composites Under a Multistage Cyclic Loading

    Science.gov (United States)

    Strizhius, V.

    2016-11-01

    Problems on estimation of the residual fatigue life of laminated composites under a multistage regular cyclic loading (with a constant amplitude at each loading stage) are among the most frequently ones encountered in the practice of fatigue life estimations of laminated composites. There are several methods for solving these problems, but their use not always gives results of acceptable accuracy. To improve the accuracy of such estimations for the type of cyclic loading mentioned, a special model of nonlinear accumulation of fatigue damage is proposed.

  12. Natural fabric sandwich laminate composites: development and investigation

    Indian Academy of Sciences (India)

    C K ARVINDA PANDIAN; H SIDDHI JAILANI; A RAJADURAI

    2017-02-01

    In this work, eco-friendly natural fabric sandwich laminate (NFSL) composites are formulated using jute and linen-fabric-reinforced epoxy with different layer ratios (5:0, 4:1, 3:2, 2:3, 1:4 and 0:5) by hand layup system. Different mechanical attributes (tensile, flexural and impact) of the NFSL composites are quantified. Thermal stability and water absorption behaviour of the NFSL composites are also assessed. A scanning electron microscope (SEM) and optical microscope are used for qualitative analysis of NFSL composites’ interfacial properties. Two layers of jute and three layers of linen sandwich laminate have registered peak values in tensile and impact properties. The five layers of linen laminate composite have exhibited high flexural strength, been proven to have good thermal stability and furthermore shown better water absorption behaviour than any other laminate composites.

  13. Nonlinear progressive damage model for composite laminates used for low velocity impact%三维渐进损伤的复合材料层合板低速冲击模型

    Institute of Scientific and Technical Information of China (English)

    郭卫

    2014-01-01

    为了有效反映复合材料层合板面内和层间的非线性损伤,建立了一个新型的损伤模型,该模型基于三维实体单元和内聚力单元可以有效分析复合材料层合板在低速冲击作用下的层内和层间非线性失效行为。对于复合材料层合板面内损伤,以改进的Hashin失效准则作为起始损伤准则,提出了一种基于能量释放率的损伤变量指数渐进演化模型,既描述了复合材料损伤的渐进失效过程,又避免了材料刚度突然下降导致刚度矩阵奇异的不足,同时引入特征长度来降低结果对网格的依赖性,最终建立了单层板的渐进损伤非线性分析模型;针对层合板的层间损伤,采用内聚力单元来模拟,通过结合传统的应力失效准则和断裂力学中的能量释放率准则定义了界面损伤演化规律。该损伤模型通过商用有限元软件ABAQUS/Explicit 的用户子程序VUMAT实现,并使用该模型对碳纤维增强环氧树脂复合材料层合板在横向低速冲击作用下的损伤和变形行为进行预测分析。数值仿真的结果与试验结果进行了比较,吻合良好,验证了该模型的有效性。%In order to effectively describe the progressively intralaminar and interlaminar damage for composite laminates , a three dimensional progressive damage model for composite laminates used for low-velocity impact is presented in this paper .Being applied to three di-mensional solid elements and cohesive elements , this nonlinear damage model can be used to analyze the dynamic performance of composite structure and its failure behavior .For the in-tralaminar damage , as a function of energy release rate , this damage model in an exponential function can describe progressive development of the damage;for interlaminar damage , dam-age evolution was described by the framework of the continuum mechanics through cohesive elements.Through coding user subroutine VUMAT of finite

  14. Determination of fatigue cracking direction in composite laminates

    Institute of Scientific and Technical Information of China (English)

    DAI Yao; HAO Gui-xiang; LI Yong-dong; HE Jia-wen; CUI Jian-guo; LI Nian; FU Yong-hui; SUN Jun

    2005-01-01

    The interface plays the central role in the failure analysis of composite laminates, therefore, the interface material properties are taken as the independent parameters. A simple, universal and practicable criterion, i.e. a ratio criterion of strain energy release rate, is proposed to determine the growing direction of a fatigue crack in the composite laminates. The method of arbitrary lines, which is very effective to solve the problems with high gradient feature, is used to analyze the experimental results at the key moments when a crack kinks, turns into the interface,or bifurcates. An approximate method of computing the energy release rate is given. The fatigue fracture tests of composite laminates are carried out, and the numerical predictions of crack growing directions agree well with the experimental results. It is concluded that the methods suggested in this paper are effective to obtain the cracking history and the growing path of a fatigue crack in composite laminates.

  15. Support Assembly for Composite Laminate Materials During Roll Press Processing

    Science.gov (United States)

    Catella, Luke A.

    2011-01-01

    A composite laminate material is supported during the roll press processing thereof by an assembly having: first and second perforated films disposed adjacent to first and second opposing surfaces of a mixture of uncured resin and fibers defining the composite laminate material, a gas permeable encasement surrounding the mixture and the first and second films, a gas impervious envelope sealed about the gas permeable encasement, and first and second rigid plates clamped about the gas impervious envelope.

  16. Residual stresses and their effects in composite laminates

    Science.gov (United States)

    Hahn, H. T.; Hwang, D. G.

    1983-01-01

    Residual stresses in composite laminates are caused by the anisotropy in expansional properties of constituent unidirectional plies. The effect of these residual stresses on dimensional stability is studied through the warping of unsymmetric (0 sub 4/90 sub 4)sub T graphite/epoxy laminates while their effect on ply failure is analyzed for (0/90)sub 2s Kevlar 49/epoxy laminate. The classical laminated plate theory is used to predict the warping of small and large panels. The change of warping does not indicate a noticeable stress relaxation at 75 C while it is very sensitive to moisture content and hence to environment. A prolonged gellation at the initial cure temperature reduces residual stresses while postcure does not. The matrix/interface cracking in dry (0/90)sub 2s Kevlar 49/epoxy laminate is shown to be the result of the residual stress exceeding the transverse strength.

  17. Fatigue Performance of Composite Laminates After Low-velocity Impact

    Directory of Open Access Journals (Sweden)

    LIANG Xiao-lin

    2016-12-01

    Full Text Available Compression-compression fatigue tests were carried out on T300/5405 composite laminates after low-velocity impact, compression performance of the laminates with different impact damages was studied together with its fatigue life and damage propagation under different stress levels, then the effects of impact energy, stress level and damage propagation on fatigue life of laminates were discussed. The results indicate that impact damage can greatly reduce the residual strength of laminates; under low fatigue load levels, the higher impact energy is, the shorter the fatigue life of laminates with impact damage will be; damage propagation undergoes two stages during the fatigue test, namely the steady propagation and the rapid propagation, accounting for 80% and 20% of the overall fatigue life, respectively; damage propagation rate decreases with the reduction of stress level.

  18. Ballistic Impact on Glass/Epoxy Composite Laminates

    Directory of Open Access Journals (Sweden)

    R. Velmurugan

    2014-07-01

    Full Text Available Glass/epoxy composite laminates are subjected to impact loading and the energy absorbing capacity of the laminates is studied. In the present study, laminates with four different orientations and thickness values are considered. Analytical study is carried out based on energy method and results are compared with FE results obtained from Abaqus/Explicit software. Results obtained from the analytical methods are showing good agreement with the FE results. It is found that cross-ply laminates are most efficient in ballistic resistance when compared with the laminates of other orientations. It is also noticed that the energy absorbing capacity is decreasing with increase in velocity of the projectile for a given lay-up and thickness value.Defence Science Journal, Vol. 64, No. 4, July 2014, pp. 393-399, DOI:http://dx.doi.org/10.14429/dsj.64.3882 

  19. Reliability Based Optimization of Composite Laminates for Frequency Constraint

    Institute of Scientific and Technical Information of China (English)

    Wu Hao; Yan Ying; Liu Yujia

    2008-01-01

    The reliability based optimization (RBO) issue of composite laminates under fundamental frequency constraint is studied. Considering the uncertainties of material properties, the frequency constraint reliability of the structure is evaluated by the combination of response surface method (RSM) and finite element method. An optimization algorithm is developed based on the mechanism of laminate frequency characteristics, to optimize the laminate in terms of the ply amount and orientation angles. Numerical examples of composite laminates and cylindrical shell illustrate the advantages of the present optimization algorithm on the efficiency and applicability respects.The optimal solutions of RBO are obviously different from the deterministic optimization results, and the necessity of considering material property uncertainties in the composite srtuctural frequency constraint optimization is revealed.

  20. Analysis of nonlinear deformations and damage in CFRP textile laminates

    Science.gov (United States)

    Ullah, H.; Harland, A. R.; Lucas, T.; Price, D.; Silberschmidt, V. V.

    2011-07-01

    Carbon fibre-reinforced polymer (CFRP) textile composites are widely used in aerospace, automotive and construction components and structures thanks to their relatively low production costs, higher delamination and impact strength. They can also be used in various products in sports industry. These products are usually exposed to different in-service conditions such as large bending deformation and multiple impacts. Composite materials usually demonstrate multiple modes of damage and fracture due to their heterogeneity and microstructure, in contrast to more traditional homogeneous structural materials like metals and alloys. Damage evolution affects both their in-service properties and performance that can deteriorate with time. These damage modes need adequate means of analysis and investigation, the major approaches being experimental characterisation, numerical simulations and microtomography analysis. This research deals with a deformation behaviour and damage in composite laminates linked to their quasi-static bending. Experimental tests are carried out to characterise the behaviour of woven CFRP material under large-deflection bending. Two-dimensional finite element (FE) models are implemented in the commercial code Abaqus/Explicit to study the deformation behaviour and damage in woven CFRP laminates. Multiple layers of bilinear cohesive-zone elements are employed to model the onset and progression of inter-ply delamination process. X-ray Micro-Computed Tomography (MicroCT) analysis is carried out to investigate internal damage mechanisms such as cracking and delaminations. The obtained results of simulations are in agreement with experimental data and MicroCT scans.

  1. Direct Composite Laminate Veneers: Three Case Reports

    OpenAIRE

    Korkut, Bora; Yanıkoğlu, Funda; GÜNDAY, Mahir

    2013-01-01

    Re-establishing a patient’s lost dental esthetic appearance is one of the most important topics for contemporary dentistry. New treatment materials and methods have been coming on the scene, day by day, in order to achieve such an aim. Most dentists prefer more conservative and aesthetic approaches, such as direct and indirect laminate veneer restorations, instead of full-ceramic crowns for anteriors where aesthetics is really important. Laminate veneers are restorations which are envisioned ...

  2. The strength of composite repair patches - A laminate analysis approach

    Science.gov (United States)

    Robson, J. E.; Matthews, F. L.; Kinloch, A. J.

    1992-07-01

    Some guidelines for the selection of extra plies for vacuum-pressure-cured composite repair patches are deduced by comparing the strength and stiffness of vacuum-cured materials with their autoclaved counterparts, using classical laminate analysis. The guidelines are based on the minimum number of extra plies needed to equal or exceed the stiffness or strength of an autoclave-cured laminate, when using vacuum curing methods. Strength and stiffness data are presented in tabular form for quasi-isotropic laminates, cross-ply laminates, and angle-ply laminates. The analysis does not take into account repair geometry, and is concerned with intrinsic laminate properties. It is found that adding extra plies to a laminate will never be detrimental to its strength and stiffness, but in order to be beneficial, the extra plies need to be aligned with a load direction. If a laminate is likely to be under a combination of loads it is important for a balance of strengths to be maintained.

  3. Tensile stress-strain behavior of hybrid composite laminates

    Science.gov (United States)

    Kennedy, J. M.

    1983-01-01

    A study was made of the stress-strain response of several hybrid laminates, and the damage was correlated with nonlinear stress-strain response and ultimate strength. The fibers used in the laminates were graphite, S-glass, and Kevlar. Some laminates with graphite fibers had perforated Mylar film between plies, which lowered the interlaminar bond strength. The laminate configurations were chosen to be like those of buffer strips in large panels and fracture coupons. Longitudinal and transverse specimens were loaded in tension to failure. Some specimens were radiographed to reveal damage due to edge effects. Stress-strain response is discussed in terms of damage shown by the radiographs. Ultimate strengths are compared with simple failure criteria, one of which account for damage.

  4. Buckling and Delamination Growth Analysis of Composite Laminates Containing Embedded Delaminations

    Science.gov (United States)

    Hosseini-Toudeshky, H.; Hosseini, S.; Mohammadi, B.

    2010-04-01

    The objective of this work is to study the post buckling behavior of composite laminates, containing embedded delamination, under uniaxial compression loading. For this purpose, delamination initiation and propagation is modeled using the softening behavior of interface elements. The full layer-wise plate theory is also employed for approximating the displacement field of laminates and the interface elements are considered as a numerical layer between any two adjacent layers which delamination is expected to propagate. A finite element program was developed and the geometric non-linearity in the von karman sense is incorporated to the strain/displacement relations, to obtain the buckling behavior. It will be shown that, the buckling load, delamination growth process and buckling mode of the composite plates depends on the size of delamination and stacking sequence of the laminates.

  5. Tunable characteristics of bending resonance frequency in magnetoelectric laminated composites

    Institute of Scientific and Technical Information of China (English)

    Chen Lei; Li Ping; Wen Yu-Mei; Zhu Yong

    2013-01-01

    As the magnetoelectric (ME) effect in piezoelectric/magnetostrictive laminated composites is mediated by mechanical deformation,the ME effect is significantly enhanced in the vicinity of resonance frequency.The bending resonance frequency (fr) of bilayered Terfenol-D/PZT (MP) laminated composites is studied,and our analysis predicts that (i) the bending resonance frequency of an MP laminated composite can be tuned by an applied dc magnetic bias (Hdc) due to the △E effect; (ii) the bending resonance frequency of the MP laminated composite can be controlled by incorporating FeCuNbSiB layers with different thicknesses.The experimental results show that with Hdc increasing from 0Oe (1 Oe=79.5775 A/m)to 700 Oe,the bending resonance frequency can be shifted in a range of 32.68 kHz ≤ fr ≤ 33.96 kHz.In addition,with the thickness of the FeCuNbSiB layer increasing from 0 μm to 90 μm,the bending resonance frequency of the MP laminated composite gradually increases from 33.66 kHz to 39.18 kHz.This study offers a method of adjusting the strength of dc magnetic bias or the thicknesses of the FeCuNbSiB layer to tune the bending resonance frequency for ME composite,which plays a guiding role in the ME composite design for real applications.

  6. Plasticity Tool for Predicting Shear Nonlinearity of Unidirectional Laminates Under Multiaxial Loading

    Science.gov (United States)

    Wang, John T.; Bomarito, Geoffrey F.

    2016-01-01

    This study implements a plasticity tool to predict the nonlinear shear behavior of unidirectional composite laminates under multiaxial loadings, with an intent to further develop the tool for use in composite progressive damage analysis. The steps for developing the plasticity tool include establishing a general quadratic yield function, deriving the incremental elasto-plastic stress-strain relations using the yield function with associated flow rule, and integrating the elasto-plastic stress-strain relations with a modified Euler method and a substepping scheme. Micromechanics analyses are performed to obtain normal and shear stress-strain curves that are used in determining the plasticity parameters of the yield function. By analyzing a micromechanics model, a virtual testing approach is used to replace costly experimental tests for obtaining stress-strain responses of composites under various loadings. The predicted elastic moduli and Poisson's ratios are in good agreement with experimental data. The substepping scheme for integrating the elasto-plastic stress-strain relations is suitable for working with displacement-based finite element codes. An illustration problem is solved to show that the plasticity tool can predict the nonlinear shear behavior for a unidirectional laminate subjected to multiaxial loadings.

  7. Design and Ballistic Performance of Hybrid Composite Laminates

    Science.gov (United States)

    Ćwik, Tomasz K.; Iannucci, Lorenzo; Curtis, Paul; Pope, Dan

    2016-10-01

    This paper presents an initial design assessment of a series of novel, cost-effective, and hybrid composite materials for applications involving high velocity impacts. The proposed hybrid panels were designed in order to investigate various physical phenomenon occurring during high velocity impact on compliant laminates from a previous study on Dyneema® and Spectra®. In the first, screening phase of the study twenty different hybrid composite laminates were impacted with 20 mm Fragment Simulating Projectiles at 1 km/s striking velocity. The best performing concepts were put forward to phase II with other hybrid concepts involving shear thickening fluids, commonly used in low velocity impacts. The results indicated that it is possible to design hybrid laminates of similar ballistic performance as the reference Dyneema® laminate, but with lower material costs. The optimal hybrid concept involves a fibre reinforced Polypropylene front and a Dyneema® backing.

  8. Fracture behavior of hybrid composite laminates

    Science.gov (United States)

    Kennedy, J. M.

    1983-01-01

    The tensile fracture behavior of 15 center-notched hybrid laminates was studied. Three basic laminate groups were tested: (1) a baseline group with graphite/epoxy plies, (2) a group with the same stacking sequence but where the zero-deg plies were one or two plies of S-glass or Kevlar, and (3) a group with graphite plies but where the zero-deg plies were sandwiched between layers of perforated Mylar. Specimens were loaded linearly with time; load, far field strain, and crack opening displacement (COD) were monitored. The loading was stopped periodically and the notched region was radiographed to reveal the extent and type of damage (failure progression). Results of the tests showed that the hybrid laminates had higher fracture toughnesses than comparable all-graphite laminates. The higher fracture toughness was due primarily to the larger damage region at the ends of the slit; delamination and splitting lowered the stress concentration in the primary load-carrying plies. A linear elastic fracture analysis, which ignored delamination and splitting, underestimated the fracture toughness. For almost all of the laminates, the tests showed that the fracture toughness increased with crack length. The size of the damage region at the ends of the slit and COD measurements also increased with crack length.

  9. Fatigue Behavior for Composite Laminates with Circular Hole

    Institute of Scientific and Technical Information of China (English)

    Qi Hongyu; Wen Weidong; Sun Lianwen

    2004-01-01

    Based on the fatigue model of exponential function and WN criterion of static strength for the composite material laminates with a circular hole, the stress correct factorβ is presented. In order to gain the factorβ, the fatigue experiments of laminates with holes in different diameters and the same ratio of width and diameter. The fatigue behavior is usually accompanied with extensive damages. Those damages can affect composite materials in their strength and stiffness. The new model based on damage theory and strain equivalent hypothesis meets engineering requirement.T300/KH304, which is recently studied, is a high capability composite material. The fatigue analysis and tests of laminates with a hole in diameter of 5 mm are carried under difference stress levels. The simple, prompt and practical method was provided for the predication of fatigue life of composite material plate with a circular hole.

  10. Computational modeling of failure in composite laminates

    NARCIS (Netherlands)

    Van der Meer, F.P.

    2010-01-01

    There is no state of the art computational model that is good enough for predictive simulation of the complete failure process in laminates. Already on the single ply level controversy exists. Much work has been done in recent years in the development of continuum models, but these fail to predict t

  11. Optimal Design of Laminated Composite Beams

    DEFF Research Database (Denmark)

    Blasques, José Pedro Albergaria Amaral

    . Furthermore, the devised beam model is able account for the different levels of anisotropic elastic couplings which depend on the laminate lay-up. An optimization model based on multi-material topology optimization techniques is described. The design variables represent the volume fractions of the different...

  12. Optimum design of laminated composite under axial compressive load

    Indian Academy of Sciences (India)

    N G R Iyengar; Nilesh Vyas

    2011-02-01

    In the present study optimal design of composite laminates, with and without rectangular cut-out, is carried out for maximizing the buckling load. Optimization study is carried out for obtaining the maximum buckling load with design variables as ply thickness, cut-out size and orientation of cut-out with respect to laminate. Buckling load is evaluated using a ‘simple higher order shear deformation theory’ based on four unknown displacements $u,v,w_b$ and $w_s$. A C1 continuous shear flexible finite element based on HSDT model is developed using Hermite cubic polynomial. It is observed that for thick anti-symmetric laminates, the non-dimensional buckling load decreases with increase in aspect ratio and increase in fibre orientation angle. There is a decrease in the non-dimensional buckling load of symmetric laminate in the presence of cut-out.

  13. Vibration analysis of composite laminate plate excited by piezoelectric actuators.

    Science.gov (United States)

    Her, Shiuh-Chuan; Lin, Chi-Sheng

    2013-01-01

    Piezoelectric materials can be used as actuators for the active vibration control of smart structural systems. In this work, piezoelectric patches are surface bonded to a composite laminate plate and used as vibration actuators. A static analysis based on the piezoelectricity and elasticity is conducted to evaluate the loads induced by the piezoelectric actuators to the host structure. The loads are then employed to develop the vibration response of a simply supported laminate rectangular plate excited by piezoelectric patches subjected to time harmonic voltages. An analytical solution of the vibration response of a simply supported laminate rectangular plate under time harmonic electrical loading is obtained and compared with finite element results to validate the present approach. The effects of location and exciting frequency of piezoelectric actuators on the vibration response of the laminate plate are investigated through a parametric study. Numerical results show that modes can be selectively excited, leading to structural vibration control.

  14. Crush testing, characterizing, and modeling the crashworthiness of composite laminates

    Science.gov (United States)

    Garner, David Michael, Jr.

    Research in the field of crashworthiness of composite materials is presented. A new crush test method was produced to characterize the crush behavior of composite laminates. In addition, a model of the crush behavior and a method for rank ordering the energy absorption capability of various laminates were developed. The new crush test method was used for evaluating the crush behavior of flat carbon/epoxy composite specimens at quasi-static and dynamic rates. The University of Utah crush test fixture was designed to support the flat specimen against catastrophic buckling. A gap, where the specimen is unsupported, allowed unhindered crushing of the specimen. In addition, the specimen's failure modes could be clearly observed during crush testing. Extensive crush testing was conducted wherein the crush force and displacement data were collected to calculate the energy absorption, and high speed video was captured during dynamic testing. Crush tests were also performed over a range of fixture gap heights. The basic failure modes were buckling, crack growth, and fracture. Gap height variations resulted in poorly, properly, and overly constrained specimens. In addition, guidelines for designing a composite laminate for crashworthiness were developed. Modeling of the crush behavior consisted of the delamination and fracture of a single ply or group of like plies during crushing. Delamination crack extension was modeled using the mode I energy release rate, G lc, where an elastica approach was used to obtain the strain energy. Variations in Glc were briefly explored with double cantilever beam tests wherein crack extension occurred along a multidirectional ply interface. The model correctly predicted the failure modes for most of the test cases, and offered insight into how the input parameters affect the model. The ranking method related coefficients of the laminate and sublaminate stiffness matrices, the ply locations within the laminate, and the laminate thickness. The

  15. Using lamb waves tomonitor moisture absorption thermally fatigues composite laminates

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Sun; Cho, Youn Ho [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of)

    2016-06-15

    Nondestructive evaluation for material health monitoring is important in aerospace industries. Composite laminates are exposed to heat cyclic loading and humid environment depending on flight conditions. Cyclic heat loading and moisture absorption may lead to material degradation such as matrix breaking, debonding, and delamination. In this paper, the moisture absorption ratio was investigated by measuring the Lamb wave velocity. The composite laminates were manufactured and subjected to different thermal aging cycles and moisture absorption. For various conditions of these cycles, not only changes in weight and also ultrasonic wave velocity were measured, and the Lamb wave velocity at various levels of moisture on a carbon-epoxy plate was investigated. Results from the experiment show a linear correlation between moisture absorption ratio and Lamb wave velocity at different thermal fatigue stages. The presented method can be applied as an alternative solution in the online monitoring of composite laminate moisture levels in commercial flights.

  16. Hybrid Titanium Composite Laminates: A New Aerospace Material

    Science.gov (United States)

    Johnson, W. S.; Cobb, Ted Q.; Lowther, Sharon; St.Clair, T. L.

    1998-01-01

    In the realm of aerospace design and performance, there are few boundaries in the never-ending drive for increased performance. This thirst for ever-increased performance of aerospace equipment has driven the aerospace and defense industries into developing exotic, extremely high-performance composites that are pushing the envelope in terms of strength-to-weight ratios, durability, and several other key measurements. To meet this challenge of ever-increasing improvement, engineers and scientists at NASA-Langley Research Center (NASA-LaRC) have developed a high-temperature metal laminate based upon titanium, carbon fibers, and a thermoplastic resin. This composite, known as the Hybrid Titanium Composite Laminate, or HTCL, is the latest chapter in a significant, but relatively short, history of metal laminates.

  17. Investigating Delamination Migration in Composite Tape Laminates

    Science.gov (United States)

    Ratcliffe, James G.; DeCarvalho, Nelson V.

    2014-01-01

    A modification to a recently developed test specimen designed to investigate migration of a delamination between neighboring ply interfaces in tape laminates is presented. The specimen is a cross-ply laminated beam consisting of 40 plies with a polytetrafluoroethylene insert spanning part way along its length. The insert is located between a lower 0-degree ply (specimen length direction) and a stack of four 90-degree plies (specimen width direction). The modification involved a stacking sequence that promotes stable delamination growth prior to migration, and included a relocation of the insert from the specimen midplane to the interface between plies 14 and 15. Specimens were clamped at both ends onto a rigid baseplate and loaded on their upper surface via a piano hinge assembly, resulting in a predominantly flexural loading condition. Tests were conducted with the load-application point positioned at various locations along a specimen's span. This position affected the sequence of damage events during a test.

  18. The role of nonlinear viscoelasticity on the functionality of laminating shortenings

    Energy Technology Data Exchange (ETDEWEB)

    Macias-Rodriguez, Braulio A.; Peyronel, Fernanda; Marangoni, Alejandro G.

    2017-11-01

    The rheology of fats is essential for the development of homogeneous and continuous layered structures of doughs. Here, we define laminating shortenings in terms of rheological behavior displayed during linear-to-nonlinear shear deformations, investigated by large amplitude oscillatory shear rheology. Likewise, we associate the rheological behavior of the shortenings with structural length scales elucidated by ultra-small angle x-ray scattering and cryo-electron microscopy. Shortenings exhibited solid-like viscoelastic and viscoelastoplastic behaviors in the linear and nonlinear regimes respectively. In the nonlinear region, laminating shortenings dissipated more viscous energy (larger normalized dynamic viscosities) than a cake bakery shortening. The fat solid-like network of laminating shortening displayed a three-hierarchy structure and layered crystal aggregates, in comparison to two-hierarchy structure and spherical-like crystal aggregates of a cake shortening. We argue that the observed rheology, correlated to the structural network, is crucial for optimal laminating performance of shortenings.

  19. Sigma phase formation kinetics in stainless steel laminate composites

    Energy Technology Data Exchange (ETDEWEB)

    Wenmen, D.W.; Olson, D.L.; Matlock, D.K. [Colorado School of Mines, Golden, CO (United States)] [and others

    1994-12-31

    Stainless steel laminate composites were made to simulate weld microstructures. The use of laminates with variations in chemical composition allows for one dimensional analysis of phase transformation associated with the more complex three-dimensional solidification experience of weld metal. Alternate layers of austenitic (304L and 316L) and ferritic (Ebrite) stainless steels allowed for the study of sigma phase formation at the austenite-ferrite interface in duplex stainless steel. Two austenitic stainless steels, 304L (18.5Cr-9.2Ni-0.3Mo) and 316L (16.2Cr-10.1Ni-2.6Mo), and one ferritic stainless steel, Ebrite (26.3Cr-0Ni-1.0Mo) were received in the form of sheet which was laboratory cold rolled to a final thickness of 0.25 mm (0.030 in.). Laminate composites were prepared by laboratory hot rolling a vacuum encapsulated compact of alternating layers of the ferrite steel with either 304L or 316L stainless steel sheets. Laminate composite specimens, which simulate duplex austenite-ferrite weld metal structure, were used to establish the kinetics of nucleation and growth of sigma phase. The factors affecting sigma phase formation were identified. The effects of time, temperature, and transport of chromium and nickel were evaluated and used to establish a model for sigma phase formation in the austenite-ferrite interfacial region. Information useful for designing stainless steel welding consumables to be used for high temperature service was determined.

  20. Acoustic plane wave reflection from a composite laminate: normal incidence

    NARCIS (Netherlands)

    Bagchi, A.; Bose, S.K.

    1994-01-01

    In using ultrasonic non-destructive evaluation methods for composite laminates, some features appear which are essentially due to the heterogeneity of the material. In performing backscattering phenomena, one such feature is the seemingly random backscattered amplitude with change of position in a c

  1. An advanced higher-order theory for laminated composite plates with general lamination angles

    Institute of Scientific and Technical Information of China (English)

    Zhen Wu; Hong Zhu; Wan-Ji Chen

    2011-01-01

    This paper proposes a higher-order shear deformation theory to predict the bending response of the laminated composite and sandwich plates with general lamination configurations.The proposed theory a priori satisfies the continuity conditions of transverse shear stresses at interfaces.Moreover,the number of unknown variables is independent of the number of layers.The first derivatives of transverse displacements have been taken out from the inplane displacement fields,so that the C0 shape functions are only required during its finite element implementation.Due to C0 continuity requirements,the proposed model can be conveniently extended for implementation in commercial finite element codes.To verify the proposed theory,the fournode C0 quadrilateral element is employed for the interpolation of all the displacement parameters defined at each nodal point on the composite plate.Numerical results show that following the proposed theory,simple C0 finite elements could accurately predict the interlaminar stresses of laminated composite and sandwich plates directly from a constitutive equation,which has caused difficulty for the other global higher order theories.

  2. Transient impact responses of laminated composite cylindrical shells

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The generalized ray method(GRM) has been successfully used to study the transient elastic wave transmitting in the beams,planar trusses,space frames and infinite layered media.In this letter,the GRM is extended to investigate the early short time transient responses of laminated composite cylindrical shells under impact load.By using the Laplace transformation and referring to the boundary conditions,the ray groups transmitting in the finite laminated cylindrical shells under the shock load are obtained ...

  3. A damping mechanics model and a beam finite element for the free-vibration of laminated composite strips under in-plane loading

    Science.gov (United States)

    Chortis, Dimitris I.; Chrysochoidis, Nikos A.; Varelis, Dimitris S.; Saravanos, Dimitris A.

    2011-11-01

    A theoretical framework is presented for predicting the nonlinear damping and damped vibration of laminated composite strips due to large in-plane forces. Nonlinear Green-Lagrange axial strains are introduced in the governing equations of a viscoelastic composite and new nonlinear damping and stiffness matrices are formulated including initial stress effects. Building upon the nonlinear laminate mechanics, a damped beam finite element is developed. Finite element stiffness and damping matrices are synthesized and the static equilibrium is predicted using a Newton-Raphson solver. The corresponding linearized damped free-vibration response is predicted and modal frequencies and damping of the in-plane deflected strip are calculated. Numerical results quantify the nonlinear effect of in-plane loads on structural modal damping of various laminated composite strips. The modal loss-factors and natural frequencies of cross-ply Glass/Epoxy beams subject to in-plane loading are measured and correlated with numerical results.

  4. Influence of mechanical load bias on converse magnetoelectric laminate composites

    Science.gov (United States)

    Wu, Tao; Emmons, Michael; Chung, Tien-Kan; Sorge, Jian; Carman, Gregory P.

    2010-05-01

    A piezofiber/Metglas (PFM) magnetoelectric (ME) laminate has been integrated into a graphite epoxy composite (GEC) to study the converse ME effect (CME). Experimental data on a PFM/GEC subjected to both a dc magnetic field bias and a dc mechanical load bias while exciting it with an ac electric driving voltage are presented. Results of these tests indicate that both the mechanical load and the dc magnetic field strongly influence the CME response. Furthermore, an optimum mechanical load exists to maximize the CME coefficient, which should also be present in standalone ME laminates. These results reveal that the CME coefficient can be further increased with a proper mechanical load bias. Therefore, the selection of an appropriate mechanical preload as well as dc magnetic bias will maximize the CME response and sensitivity in ME laminates as well as integrated structural systems.

  5. Interlaminar damage of carbon fiber reinforced polymer composite laminate under continuous wave laser irradiation

    Science.gov (United States)

    Liu, Yan-Chi; Wu, Chen-Wu; Huang, Yi-Hui; Song, Hong-Wei; Huang, Chen-Guang

    2017-01-01

    The interlaminar damages were investigated on the carbon fiber reinforced polymer (CFRP) composite laminate under laser irradiation. Firstly, the laminated T700/BA9916 composites were exposed to continuous wave laser irradiation. Then, the interface cracking patterns of such composite laminates were examined by optical microscopy and scanning electron microscopy. Finally, the Finite Element Analysis (FEA) was performed to compute the interface stress of the laminates under laser irradiation. And the effects of the laser parameters on the interlaminar damage were discussed.

  6. The impact properties of laminated composites containing ultrahigh carbon (UHC) steels

    Science.gov (United States)

    Kum, D. W.; Oyama, T.; Wadsworth, J.; Sherby, O. D.

    AN ULTRAHIGH carbon (UHC) steel/mild steel laminated composite and a UHC steel/UHC steel laminate have been successfully manufactured by a roll-bonding procedure. Impact properties of these laminates, as well as of monolithic samples of the steels contained in these laminates, have been determined in the crackarrestor orientation over the temperature range 25 to -196°C. Both notched and unnotched samples of the laminated composite and laminate have been tested. Extremely low ductile-to-brittle temperatures of -140°C, and very high shelf energies (>325 J), have been found both for the laminated composites and the laminates. This remarkably good behavior is shown to be a result of notch blunting by delamination within the laminates.

  7. Vibration suppression for laminated composite plates with arbitrary boundary conditions

    Science.gov (United States)

    Li, J.; Narita, Y.

    2013-11-01

    An analysis of vibration suppression for laminated composite plates subject to active constrained layer damping under various boundary conditions is presented. Piezoelectric-fiber-reinforced composites (PFRCs) are used as active actuators, and the effect of PFRC patches on vibration control is reported here. An analytical approach is expanded to analyze the vibration of laminated composites with arbitrary boundary conditions. By using Hamilton's principle and the Rayleigh-Ritz method, the equation of motion for the resulting electromechanical coupling system is derived. A velocity feedback control rule is employed to obtain an effective active damping in the vibration control. The orientation effect of piezoelectric fibers in the PFRC patches on the suppression of forced vibrations is also investigated.

  8. Finite element modeling of consolidation of composite laminates

    Institute of Scientific and Technical Information of China (English)

    Xiangqiao Yan

    2006-01-01

    Advanced fiber reinforced polymer composites have been increasingly applied to various structural corn-ponents.One of the important processes to fabricate high performance laminated composites is an autoclave assisted prepreg lay-up.Since the quality of laminated composites is largely affected by the cure cycle,selection of an appropriate cure cycle for each application is important and must be opti-mized.Thus.some fundamental model of the consolidation and cure processes is necessary for selecting suitable param-eters for a specific application.This article is concerned with the "flow-compaction" model during the autoclave process-ing of composite materials.By using a weighted residual method,two-dimensional finite element formulation for the consolidation process of thick thermosetting composites is presented and the corresponding finite element code is developed.Numerical examples.including comparison of the present numerical results with one-dimensional and two-dimensional analytical solutions,are given to illustrate the accuracy and effectiveness of the proposed finite element formulation.In addition,a consolidation simulation of As4/3501-6 graphite/epoxy laminate is carried out and compared with the experimental results available in the literature.

  9. Autoclave processing for composite material fabrication. 1: An analysis of resin flows and fiber compactions for thin laminate

    Science.gov (United States)

    Hou, T. H.

    1985-01-01

    High quality long fiber reinforced composites, such as those used in aerospace and industrial applications, are commonly processed in autoclaves. An adequate resin flow model for the entire system (laminate/bleeder/breather), which provides a description of the time-dependent laminate consolidation process, is useful in predicting the loss of resin, heat transfer characteristics, fiber volume fraction and part dimension, etc., under a specified set of processing conditions. This could be accomplished by properly analyzing the flow patterns and pressure profiles inside the laminate during processing. A newly formulated resin flow model for composite prepreg lamination process is reported. This model considers viscous resin flows in both directions perpendicular and parallel to the composite plane. In the horizontal direction, a squeezing flow between two nonporous parallel plates is analyzed, while in the vertical direction, a poiseuille type pressure flow through porous media is assumed. Proper force and mass balances have been made and solved for the whole system. The effects of fiber-fiber interactions during lamination are included as well. The unique features of this analysis are: (1) the pressure gradient inside the laminate is assumed to be generated from squeezing action between two adjacent approaching fiber layers, and (2) the behavior of fiber bundles is simulated by a Finitely Extendable Nonlinear Elastic (FENE) spring.

  10. Strength of Bolted Joints in Laminated Composites

    Science.gov (United States)

    1984-03-01

    Analysis of Single and Two-Hole Bolted Joints in Fibre Reinforced Plastic ," J. of Composite Materials, Vol. 16, 1982, pp.481-491. 11. N,J. Pagano, R.B...Effect of Stacking Sequence on the Pin-Bearing Strength in Glass Fibre Reinforced Plastic ,’ J. of Composite Materials, Vol. 11, 1977, pp. 139-145. 13., J.M

  11. 3D Guided Wave Motion Analysis on Laminated Composites

    Science.gov (United States)

    Tian, Zhenhua; Leckey, Cara; Yu, Lingyu

    2013-01-01

    Ultrasonic guided waves have proved useful for structural health monitoring (SHM) and nondestructive evaluation (NDE) due to their ability to propagate long distances with less energy loss compared to bulk waves and due to their sensitivity to small defects in the structure. Analysis of actively transmitted ultrasonic signals has long been used to detect and assess damage. However, there remain many challenging tasks for guided wave based SHM due to the complexity involved with propagating guided waves, especially in the case of composite materials. The multimodal nature of the ultrasonic guided waves complicates the related damage analysis. This paper presents results from parallel 3D elastodynamic finite integration technique (EFIT) simulations used to acquire 3D wave motion in the subject laminated carbon fiber reinforced polymer composites. The acquired 3D wave motion is then analyzed by frequency-wavenumber analysis to study the wave propagation and interaction in the composite laminate. The frequency-wavenumber analysis enables the study of individual modes and visualization of mode conversion. Delamination damage has been incorporated into the EFIT model to generate "damaged" data. The potential for damage detection in laminated composites is discussed in the end.

  12. Design feasibility study of a divertor component reinforced with fibrous metal matrix composite laminate

    Energy Technology Data Exchange (ETDEWEB)

    You, J.-H. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany)]. E-mail: j.h.you@ipp.mpg.de

    2005-01-01

    Fibrous metal matrix composites possess advanced mechanical properties compared to conventional alloys. It is expected that the application of these composites to a divertor component will enhance the structural reliability. A possible design concept would be a system consisting of tungsten armour, copper composite interlayer and copper heat sink where the composite interlayer is locally inserted into the highly stressed domain near the bond interface. For assessment of the design feasibility of the composite divertor concept, a non-linear multi-scale finite element analysis was performed. To this end, a micro-mechanics algorithm was implemented into a finite element code. A reactor-relevant heat flux load was assumed. Focus was placed on the evolution of stress state, plastic deformation and ductile damage on both macro- and microscopic scales. The structural response of the component and the micro-scale stress evolution of the composite laminate were investigated.

  13. Free Vibration of Laminated Composite Hypar Shell Roofs with Cutouts

    Directory of Open Access Journals (Sweden)

    Sarmila Sahoo

    2011-01-01

    Full Text Available Use of laminated composites in civil engineering structural components including shell roofs is increasing day by day due to their light weight, high specific strength, and stiffness properties. In the present paper, laminated composite hypar shell (hyperbolic paraboloidal shells bounded by straight edges roofs with cutouts are analyzed for their free vibration characteristics using finite element method. An eight-noded curved shell element is used for modeling the shell. Specific numerical problems of earlier investigators are solved to compare their results with the present formulation. A number of problems are further solved where the size of the cutouts and their positions with respect to the shell centre are varied for different edge constraints. The results are furnished in the form of figures and tables. The results are examined thoroughly to arrive at some meaningful conclusions useful to designers.

  14. Calculation of the fatigue life distribution of a composite laminate

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, IA.A.; Limonov, V.A. (AN LSSR, Institut Mekhaniki Polimerov, Riga, Latvian (USSR))

    1991-02-01

    A method based on a probabilistic interpretation of the Hashin criterion is proposed for calculating the fatigue life distributions of a unidirectional composite under conditions of a plane stressed state from test results obtained for simple loading schemes. By using the linear damage accumulation law, an estimate is obtained of the scatter of the composite fatigue life related to the scatter of the material fatigue strength. A procedure is then presented for estimating the fatigue life distribution of a composite laminate in the plane stressed state based on layer-by-layer fracture analysis using the linear damage summation law and the determining layer concept. 26 refs.

  15. Design and manufacturing of skins based on composite corrugated laminates for morphing aerodynamic surfaces

    Science.gov (United States)

    Airoldi, Alessandro; Fournier, Stephane; Borlandelli, Elena; Bettini, Paolo; Sala, Giuseppe

    2017-04-01

    The paper discusses the approaches for the design and manufacturing of morphing skins based on rectangular-shaped composite corrugated laminates and proposes a novel solution to prevent detrimental effects of corrugation on aerodynamic performances. Additionally, more complex corrugated shapes are presented and analysed. The manufacturing issues related to the production of corrugated laminates are discussed and tests are performed to compare different solutions and to assess the validity of analytical and numerical predictions. The solution presented to develop an aerodynamically efficient skin consists in the integration of an elastomeric cover in the corrugated laminate. The related manufacturing process is presented and assessed, and a fully nonlinear numerical model is developed and characterized to study the behaviour of this skin concept in different load conditions. Finally, configurations based on combinations of individual rectangular-shaped corrugated panels are considered. Their structural properties are numerically investigated by varying geometrical parameters. Performance indices are defined to compare structural stiffness contributions in non-morphing directions with the ones of conventional panels of the same weight. Numerical studies also show that the extension of the concept to complex corrugated shapes may improve both the design flexibility and some specific performances with respect to rectangular shaped corrugations. The overall results validate the design approaches and manufacturing processes to produce corrugated laminates and indicate that the solution for the integration of an elastomeric cover is a feasible and promising method to enhance the aerodynamic efficiency of corrugated skins.

  16. Structural Analysis of Composite Laminates using Analytical and Numerical Techniques

    Directory of Open Access Journals (Sweden)

    Sanghi Divya

    2016-01-01

    Full Text Available A laminated composite material consists of different layers of matrix and fibres. Its properties can vary a lot with each layer’s or ply’s orientation, material property and the number of layers itself. The present paper focuses on a novel approach of incorporating an analytical method to arrive at a preliminary ply layup order of a composite laminate, which acts as a feeder data for the further detailed analysis done on FEA tools. The equations used in our MATLAB are based on analytical study code and supply results that are remarkably close to the final optimized layup found through extensive FEA analysis with a high probabilistic degree. This reduces significant computing time and saves considerable FEA processing to obtain efficient results quickly. The result output by our method also provides the user with the conditions that predicts the successive failure sequence of the composite plies, a result option which is not even available in popular FEM tools. The predicted results are further verified by testing the laminates in the laboratory and the results are found in good agreement.

  17. Resin infusion of layered metal/composite hybrid and resulting metal/composite hybrid laminate

    Science.gov (United States)

    Cano, Roberto J. (Inventor); Grimsley, Brian W. (Inventor); Weiser, Erik S. (Inventor); Jensen, Brian J. (Inventor)

    2009-01-01

    A method of fabricating a metal/composite hybrid laminate is provided. One or more layered arrangements are stacked on a solid base to form a layered structure. Each layered arrangement is defined by a fibrous material and a perforated metal sheet. A resin in its liquid state is introduced along a portion of the layered structure while a differential pressure is applied across the laminate structure until the resin permeates the fibrous material of each layered arrangement and fills perforations in each perforated metal sheet. The resin is cured thereby yielding a metal/composite hybrid laminate.

  18. DAMAGE PROGRESSIVE MODEL OF COMPRESSION OF COMPOSITE LAMINATES AFTER LOW VELOCITY IMPACT

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiao-quan; LI Zheng-neng

    2005-01-01

    Compressive properties of composite laminates after low velocity impact are one of the most serious circumstances that must be taken into account in damage tolerance design of composite structures. In order to investigate compressive properties of composite laminates after low velocity impact, three dimensional dynamic finite element method (FEM) was used to simulate low-velocity impact damage of 2 kinds of composite laminates firstly. Damage distributions and projective damage areas of the laminates were predicted under two impact energy levels. The analyzed damage after impact was considered to be the initial damage of the laminates under compressive loads. Then three dimensional static FEM was used to simulate the compressive failure process and to calculate residual compressive strengths of the impact damaged laminates. It is achieved to simulate the whole process from initial low-velocity impact damage to final compressive failure of composite laminates. Compared with experimental results, it shows that the numerical predicting results agree with the test results fairly well.

  19. Flutter and Thermal Buckling Analysis for Composite Laminated Panel Embedded with Shape Memory Alloy Wires in Supersonic Flow

    Directory of Open Access Journals (Sweden)

    Chonghui Shao

    2016-01-01

    Full Text Available The flutter and thermal buckling behavior of laminated composite panels embedded with shape memory alloy (SMA wires are studied in this research. The classical plate theory and nonlinear von-Karman strain-displacement relation are employed to investigate the aeroelastic behavior of the smart laminated panel. The thermodynamic behaviors of SMA wires are simulated based on one-dimensional Brinson SMA model. The aerodynamic pressure on the panel is described by the nonlinear piston theory. Nonlinear governing partial differential equations of motion are derived for the panel via the Hamilton principle. The effects of ply angle of the composite panel, SMA layer location and orientation, SMA wires temperature, volume fraction and prestrain on the buckling, flutter boundary, and amplitude of limit cycle oscillation of the panel are analyzed in detail.

  20. Investigation on contact melting of Cu/Al laminated composite

    Directory of Open Access Journals (Sweden)

    Dmitry V. Pronichev

    2016-12-01

    Full Text Available The study presents investigation of chemical composition, microhardness and electrical conductivity of Cu/Al laminated metal composite after heat treatment at temperatures higher than Cu–Al eutectic melting point. The Cu/Al bimetal was obtained via explosion welding. Chemical composition of the material after heat treatments was identified using EDS analysis. Eddy current testing was applied to investigate electrical conductivity of the composite’s components. Strain-hardened zones were identified in the explosion welded composite. The experimental value of electrical conductivity of explosion welded composite was in good coherence with calculated by additivity rule results. Heat treatments resulted in the formation of multiple interlayers which had high microhardness value and had intermetallics in composition. The electrical conductivity of the identified interlayers was significantly lower than of Cu and Al.

  1. Performance of soft dielectric laminated composites

    Science.gov (United States)

    Gei, Massimiliano; Springhetti, Roberta; Bortot, Eliana

    2013-10-01

    This paper contains a thorough investigation of the performance of electrically activated layered soft dielectric composite actuators under plane deformation. Noting that the activation can be induced by controlling either the voltage or the surface charge, the overall behaviour of the system is obtained via homogenization at large strains, taking either the macroscopic electric field or the macroscopic electric displacement field as independent electrical variables. The performance of a two-phase composite actuator compared to that of the homogeneous case is highlighted for few boundary-value problems and for different values of stiffness and permittivity ratios between constituents being significant for applications, where the soft matrix is reinforced by a relatively small volume fraction of a stiff and high-permittivity phase. For charge-controlled devices, it is shown that some composite layouts admit, on one hand, the occurrence of pull-in/snap-through instabilities that can be exploited to design release-actuated systems, and on the other hand, the possibility of thickening at increasing surface charge density.

  2. Laminated Ti-Al composites: Processing, structure and strength

    DEFF Research Database (Denmark)

    Du, Yan; Fan, Guohua; Yu, Tianbo

    2016-01-01

    . The mechanical properties of the composites with different volume fractions of Al from 10% to 67% show a good combination of strength and ductility. A constraint strain in the hot-rolled laminated structure between the hard and soft phases introduces an elastic-plastic deformation stage, which becomes more...... pronounced as the volume fraction of Al decreases. Moreover, the thin intermetallic interface layer may also contribute to the strength of the composites, and this effect increases with increasing volume fraction of the interface layer....

  3. Periodic and chaotic dynamics of composite laminated piezoelectric rectangular plate with one-to-two internal resonance

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; YAO ZhiGang; YAO MingHui

    2009-01-01

    The bifurcations and chaotic dynamics of a simply supported symmetric cross-ply composite lami-nated piezoelectric rectangular plate are studied for the first time, which are simultaneously forced by the transverse, in-plane excitations and the excitation loaded by piezoelectric layers. Based on the Reddy's third-order shear deformation plate theory, the nonlinear governing equations of motion for the composite laminated piezoelectric rectangular plate are derived by using the Hamilton's principle. The Galerkin's approach is used to discretize partial differential governing equations to a two-degree-of-freedom nonlinear system under combined the parametric and external excitations. The method of multiple scales is employed to obtain the four-dimensional averaged equation. Numerical method is utilized to find the periodic and chaotic responses of the composite laminated piezoelectric rectangular plate. The numerical results indicate the existence of the periodic and chaotic responses in the aver-aged equation. The influence of the transverse, in-plane and piezoelectric excitations on the bifurca-tions and chaotic behaviors of the composite laminated piezoelectric rectangular plate is investigated numerically.

  4. Analysis of metal-matrix composite structures. I - Micromechanics constitutive theory. II - Laminate analyses

    Science.gov (United States)

    Arenburg, R. T.; Reddy, J. N.

    1991-01-01

    The micromechanical constitutive theory is used to examine the nonlinear behavior of continuous-fiber-reinforced metal-matrix composite structures. Effective lamina constitutive relations based on the Abouli micromechanics theory are presented. The inelastic matrix behavior is modeled by the unified viscoplasticity theory of Bodner and Partom. The laminate constitutive relations are incorporated into a first-order deformation plate theory. The resulting boundary value problem is solved by utilizing the finite element method. Attention is also given to computational aspects of the numerical solution, including the temporal integration of the inelastic strains and the spatial integration of bending moments. Numerical results the nonlinear response of metal matrix composites subjected to extensional and bending loads are presented.

  5. Effect of ellipse orientation on the thermoelastic behaviour of skew laminated composite plate with elliptical cutout

    Indian Academy of Sciences (India)

    M S R Niranjan Kumar; M M M Sarcar; V Bala Krishna Murthy; K M Rao

    2009-02-01

    An effort is made to study the thermoelastic behaviour of a cross-ply laminated composite skew plate with elliptical cutout subjected to pressure and non-linearly varying temperature loading in the present analysis. Orientation of the elliptical cut out is varied from 0° to 180° with respect to horizontal at an interval of 30° in the anti clockwise direction is considered for the present analysis. A three-dimensional heat conduction analysis in fibre reinforced composite laminates has been simulated by finite element method to get realistic temperature in the laminate under different thermal boundary conditions. A finite element method, which works on the basis of three-dimensional theory of elasticity, is employed to evaluate the stresses and deformations. The effect of orientation due to pressure loading on the stresses and transverse deflection is observed to be insignificant. The magnitudes of the in-plane normal stresses, x and y, for temperature loading are greatly affected by ellipse orientation and are observed to be minimum at the ellipse orientation of 0° and 90°, respectively. The in-plane and inter-laminar shear stresses are observed to be minimum at the ellipse orientation of 90°.

  6. Smart damping of laminated fuzzy fiber reinforced composite shells using 1-3 piezoelectric composites

    Science.gov (United States)

    Kundalwal, S. I.; Kumar, R. Suresh; Ray, M. C.

    2013-10-01

    This paper deals with the investigation of active constrained layer damping (ACLD) of smart laminated continuous fuzzy fiber reinforced composite (FFRC) shells. The distinct constructional feature of a novel FFRC is that the uniformly spaced short carbon nanotubes (CNTs) are radially grown on the circumferential surfaces of the continuous carbon fiber reinforcements. The constraining layer of the ACLD treatment is considered to be made of vertically/obliquely reinforced 1-3 piezoelectric composite materials. A finite element (FE) model is developed for the laminated FFRC shells integrated with the two patches of the ACLD treatment to investigate the damping characteristics of the laminated FFRC shells. The effect of variation of the orientation angle of the piezoelectric fibers on the damping characteristics of the laminated FFRC shells has been studied when the piezoelectric fibers are coplanar with either of the two mutually orthogonal vertical planes of the piezoelectric composite layer. It is revealed that radial growth of CNTs on the circumferential surfaces of the carbon fibers enhances the attenuation of the amplitude of vibrations and the natural frequencies of the laminated FFRC shells over those of laminated base composite shells without CNTs.

  7. Characterization of Impact in Composite Laminates

    Science.gov (United States)

    Minnaar, Karel; Zhou, Min

    2002-07-01

    A new experimental technique is developed to determine the onset and evolution of delamination in fiber-reinforced composites. The configuration uses a split-Hopkinson bar for low-velocity impact loading and two Polytec laser vibrometer systems for real-time monitoring of the initiation and progression of delamination. The experiment allows the histories of load, displacement, and velocity of impacted specimens to be recorded and analyzed. Numerical simulations are conducted using a cohesive finite element method. The method employs a cohesive zone model to simulate in-ply cracking and interlaminar delamination and a transversely isotropic, elastic model to characterize the bulk behavior of each ply. The simulations provide time-resolved characterization of damage during the impact loading. The time at which delamination is detected decreases as the impact velocity is increased, and delamination is detected at similar surface displacements. The progression of damage changes as the bonding strength between plies is increased. The speed of delamination decreases as the bonding strength is increased.

  8. Optimization of Laminated Composite Z-Section Beam

    Directory of Open Access Journals (Sweden)

    Sanjay Gupta

    2014-02-01

    Full Text Available The abstract should summarize the content of the paper. Composites are the relatively new but fast growing field where the researchers are paying their lots of attention. Ever growing market needs always better material and product which is lighter in weight but more strengthen in nature. To justify the current needs this project pays some attention to increase the performance of the composite product by means of some modern optimization techniques. The benefit of material properties and flexibility of selecting material have made composite materials a key preference for structural application. Dissimilar to isotropic materials, the parametric study of laminated composite beams for optimized design is complex due to more number of parameters concerned in designing like lay-up sequence, and layer configuration. Furthermore, the restrictions of FEA methods in designing have created a requirement for an optimum solution for analysis of laminated composite beams structure. The goal of this study focuses on the optimization of composite Z-beam for lowest deflection by a static analysis. Composite materials are extensively being used in aircraft, robotic and automotive industries where the parts are subjected to various loading situations. There is a requirement for the precise prediction of for their static response uniqueness so that they can be designed against the failure because of different types of possible static loads. Here the parameterization of composite is done and then through various parameters like number of ply, ply thickness and ply location etc. the optimization has been done to reduce the weight and other performance criteria‟s for Z-beam (thin walled composite plate.

  9. Combining Analysis of Coupled Electrical-Thermal and BLOW-OFF Impulse Effects on Composite laminate Induced by Lightning Strike

    Science.gov (United States)

    Liu, Z. Q.; Yue, Z. F.; Wang, F. S.; Ji, Y. Y.

    2015-04-01

    A comprehensive simulation procedure combining electrical-thermal analysis and BLOW-OFF impulse (BOI) analysis was conducted to investigate lightning direct effects on damage behavior of composite. The nonlinear material model was elaborated combining the damage mechanism of composite laminate subjected to lightning strike. Results of electrical-thermal analysis indicated that temperature distribution of composite laminate is mainly affected by the electrical anisotropy because of Joule heating. By comparing results of BOI analysis with lightning test, it can be found that strain fields of analysis meet well with the damage pattern of lightning specimen. It could be concluded that the analysis procedure is suitable for modeling damage of composite due to lighting strike, and results of logarithmic strain field can be used to help estimate the zone which need to be repaired for composite.

  10. Estimation of physical properties of laminated composites via the method of inverse vibration problem

    Energy Technology Data Exchange (ETDEWEB)

    Balci, Murat [Dept. of Mechanical Engineering, Bayburt University, Bayburt (Turkmenistan); Gundogdu, Omer [Dept. of Mechanical Engineering, Ataturk University, Erzurum (Turkmenistan)

    2017-01-15

    In this study, estimation of some physical properties of a laminated composite plate was conducted via the inverse vibration problem. Laminated composite plate was modelled and simulated to obtain vibration responses for different length-to-thickness ratio in ANSYS. Furthermore, a numerical finite element model was developed for the laminated composite utilizing the Kirchhoff plate theory and programmed in MATLAB for simulations. Optimizing the difference between these two vibration responses, inverse vibration problem was solved to obtain some of the physical properties of the laminated composite using genetic algorithms. The estimated parameters are compared with the theoretical results, and a very good correspondence was observed.

  11. Recent developments of discrete material optimization of laminated composite structures

    DEFF Research Database (Denmark)

    Lund, Erik; Sørensen, Rene

    2015-01-01

    This work will give a quick summary of recent developments of the Discrete Material Optimization approach for structural optimization of laminated composite structures. This approach can be seen as a multi-material topology optimization approach for selecting the best ply material and number....... The different interpolation schemes used are described, and it is briefly outlined how design rules/manufacturing constraints can be included in the optimization. The approach has been demonstrated for a number of global design criteria like mass, compliance, buckling load factors, etc., but recent work makes...

  12. Analytical and Experimental Characterization of Damage Processes in Composite Laminates

    Science.gov (United States)

    1988-06-01

    INDIVIDUAL 221L TELEPHONE NUMBER 2.6IESMO L~~~.CoL(In do~? A( meA0 ode) 00 FORM 1473, 83 APR EDITION OF I JAN 73 IS OBSOLETE. ABSTRACT This report...Mechanics of Metal Matrix Composite Laminates," Strain Localization and Size Effect Due to Cracking and Damage, edited by J. Mazars and Z.P. Bazant , Elsevier...Effect Due to Cracking and Damage, edited by J. Mazars and Z.P. Bazant , Elsevier Scientific Publishers, London, 1988. 17 14. Kaveh-Ahangar, A., Ph.D

  13. Mixed isoparametric finite element models of laminated composite shells

    Science.gov (United States)

    Noor, A. K.; Andersen, C. M.

    1977-01-01

    Mixed shear-flexible isoparametric elements are presented for the stress and free vibration analysis of laminated composite shallow shells. Both triangular and quadrilateral elements are considered. The 'generalized' element stiffness, consistent mass, and consistent load coefficients are obtained by using a modified form of the Hellinger-Reissner mixed variational principle. Group-theoretic techniques are used in conjunction with computerized symbolic integration to obtain analytic expressions for the stiffness, mass and load coefficients. A procedure is outlined for efficiently handling the resulting system of algebraic equations. The accuracy of the mixed isoparametric elements developed is demonstrated by means of numerical examples, and their advantages over commonly used displacement elements are discussed.

  14. FATIGUE LIFE PREDICTION THEORY OF COMPOSITE LAMINATES AND EXPERIMENTAL VERIFICATION

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    According to traditional phenomenological fatigue methodology and modern continuum damage mechanics theory, dual fatigue cumulative damage rules to predict fatigue damage formation and propagation lives of the notched composite laminates are presented.A 3-dimensional damage constitutive equation of anisotropic composites is also established.Damage strain energy release rate is interpreted as a driving force of the fatigue delamination damage propagation.A new damage evolution equation and a damage propagation (a-(m-N( surface (stress amplitude-mean stress-life surface) are derived.Hence, using the method above, the fatigue life of composite components can be predicted.Finally, theoretically predicted results are compared with experimental data.It is found that the deviation of theoretic prediction from experimental results is about 22%.

  15. Coupled mixed-field laminate theory and finite element for smart piezoelectric composite shell structures

    Science.gov (United States)

    Saravanos, Dimitris A.

    1996-01-01

    Mechanics for the analysis of laminated composite shells with piezoelectric actuators and sensors are presented. A new mixed-field laminate theory for piezoelectric shells is formulated in curvilinear coordinates which combines single-layer assumptions for the displacements and a layerwise representation for the electric potential. The resultant coupled governing equations for curvilinear piezoelectric laminates are described. Structural mechanics are subsequently developed and an 8-node finite-element is formulated for the static and dynamic analysis of adaptive composite structures of general laminations containing piezoelectric layers. Evaluations of the method and comparisons with reported results are presented for laminated piezoelectric-composite plates, a closed cylindrical shell with a continuous piezoceramic layer and a laminated composite semi-circular cantilever shell with discrete cylindrical piezoelectric actuators and/or sensors.

  16. A Numerical and Experimental Study of Damage Growth in a Composite Laminate

    Science.gov (United States)

    McElroy, Mark; Ratcliffe, James; Czabaj, Michael; Wang, John; Yuan, Fuh-Gwo

    2014-01-01

    The present study has three goals: (1) perform an experiment where a simple laminate damage process can be characterized in high detail; (2) evaluate the performance of existing commercially available laminate damage simulation tools by modeling the experiment; (3) observe and understand the underlying physics of damage in a composite honeycomb sandwich structure subjected to low-velocity impact. A quasi-static indentation experiment has been devised to provide detailed information about a simple mixed-mode damage growth process. The test specimens consist of an aluminum honeycomb core with a cross-ply laminate facesheet supported on a stiff uniform surface. When the sample is subjected to an indentation load, the honeycomb core provides support to the facesheet resulting in a gradual and stable damage growth process in the skin. This enables real time observation as a matrix crack forms, propagates through a ply, and then causes a delamination. Finite element analyses were conducted in ABAQUS/Explicit(TradeMark) 6.13 that used continuum and cohesive modeling techniques to simulate facesheet damage and a geometric and material nonlinear model to simulate core crushing. The high fidelity of the experimental data allows a detailed investigation and discussion of the accuracy of each numerical modeling approach.

  17. A novel tetrahedal element for static and dynamic analysis of laminated composites

    Energy Technology Data Exchange (ETDEWEB)

    Jones, I A; Ruijter, W; Long, A C, E-mail: arthur.jones@nottingham.ac.u, E-mail: woutruijter@gmail.co, E-mail: andrew.long@nottingham.ac.u [Division of Materials, Mechanics and Structures, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

    2009-08-01

    This paper presents a novel approach to formulating finite elements for modelling laminated composites. Most FE systems provide laminated composite elements based upon layered shell elements and some provide layered brick elements, but these require a hexahedral mesh which is difficult to generate for arbitrary geometries. This paper describes a tetrahedral element based on the concept of an equivalent graded material whose properties vary smoothly (rather than stepwise) and whose global behaviour replicates that of the laminate. This allows the possibility of automatically-generated models involving laminated composite behaviour. The element requires a non-standard integration system, and is presented for the cases of elastic, thermoelastic and dynamic behaviour.

  18. Ancient and Modern Laminated Composites - From the Great Pyramid of Gizeh to Y2K

    Energy Technology Data Exchange (ETDEWEB)

    Wadsworth, J.; Lesuer, D.R.

    2000-03-14

    Laminated metal composites have been cited in antiquity; for example, a steel laminate that may date as far back as 2750 B.C., was found in the Great Pyramid in Gizeh in 1837. A laminated shield containing bronze, tin, and gold layers, is described in detail by Homer. Well-known examples of steel laminates, such as an Adze blade, dating to 400 B.C. can be found in the literature. The Japanese sword is a laminated composite at several different levels and Merovingian blades were composed of laminated steels. Other examples are also available, including composites from China, Thailand, Indonesia, Germany, Britain, Belgium, France, and Persia. The concept of lamination to provide improved properties has also found expression in modern materials. Of particular interest is the development of laminates including high carbon and low carbon layers. These materials have unusual properties that are of engineering interest; they are similar to ancient welded Damascus steels. The manufacture of collectable knives, labeled ''welded Damascus'', has also been a focus of contemporary knifemakers. Additionally, in the Former Soviet Union, laminated composite designs have been used in engineering applications. Each of the above areas will be briefly reviewed, and some of the metallurgical principles will be described that underlie improvement in properties by lamination. Where appropriate, links are made between these property improvements and those that may have been present in ancient artifacts.

  19. Prediction of Degraded Strength in Composite Laminates with Matrix Cracks

    Science.gov (United States)

    Kime, Yolanda J.

    1997-01-01

    Composite laminated materials are becoming increasingly important for aerospace engineering. As the aerospace industry moves in this direction, it will be critical to be able to predict how these materials fail. While much research has been done in this area, both theoretical and experimental, the field is still new enough that most computer aided design platforms have not yet incorporated damage prediction for laminate materials. There is a gap between the level of understanding evident in the literature and what design tools are readily available to engineers. The work reported herein is a small step toward filling that gap for NASA engineers. A computer program, LAMDGRAD, has been written which predicts how some of the materials properties change as damage is incurred. Specifically, the program calculates the Young's moduli E(sub x) and E(sub y) the Poisson's ratio v(sub xy) and the shear modulus G(sub xy) as cracks developing the composite matrix. The changes in the Young's moduli are reported both as a function of mean crack separation and in the form of a stress-versus-strain curve. The program also calculates the critical strain for delamination growth and predicts the strain at which a quarter-inch diameter delaminated area will buckle. The stress-versus-strain predictions have been compared to experiment for two test structures, and good agreement has been found in each case.

  20. Strain rate effects on GRP, KRP and CFRP composite laminates

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hassani, S.T.S.; Kaddour, A.S. [University of Manchester Inst. of Science and Technology (UMIST) (United Kingdom). Dept. of Mechanical Engineering

    1998-05-01

    This paper first reviews published research work on the effect of strain-rate on the in-plane mechanical properties of continuous Kevlar (KRP), glass (GRP) and carbon (CFRP) fibre reinforced plastic materials. A detailed description of techniques employed for testing composite materials at a wide range of strain rates is given. Recent relevant test results are presented showing the variation of mechanical properties with strain rates for unidirectional and multidirectional laminates under in-plane loading. The paper then concentrates on current activities on indirect determination of unidirectional dynamic properties from the behaviour of angle ply laminates by means of an extraction process. Theoretical procedures for extracting the longitudinal, transverse and in-plane shear properties are outlined. An extension to those procedures allowing simultaneous determination of transverse and in-plane shear moduli of a ply is introduced and results using this method are presented for KRP and CFRP under combined strain rate and temperature. Existing theories and mechanisms describing the combined effects of the temperature and the strain-rate on the mechanical response of composite materials are outlined. (orig.) 98 refs.

  1. A refined mixed shear flexible finite element for the nonlinear analysis of laminated plates

    Science.gov (United States)

    Putcha, N. S.; Reddy, J. N.

    1986-01-01

    The present study is concerned with the development of a mixed shear flexible finite element with relaxed continuity for the geometrically linear and nonlinear analysis of laminated anisotropic plates. The formulation of the element is based on a refined higher-order theory. This theory satisfies the zero transverse shear stress boundary conditions on the top and bottom faces of the plate. Shear correction coefficients are not needed. The developed element consists of 11 degrees-of-freedom per node, taking into account three displacements, two rotations, and six moment resultants. An evaluation of the element is conducted with respect to the accuracy obtained in the bending of laminated anistropic rectangular plates with different lamination schemes, loadings, and boundary conditions.

  2. Microcracking in composite laminates under thermal and mechanical loading. Thesis

    Science.gov (United States)

    Maddocks, Jason R.

    1995-01-01

    Composites used in space structures are exposed to both extremes in temperature and applied mechanical loads. Cracks in the matrix form, changing the laminate thermoelastic properties. The goal of the present investigation is to develop a predictive methodology to quantify microcracking in general composite laminates under both thermal and mechanical loading. This objective is successfully met through a combination of analytical modeling and experimental investigation. In the analysis, the stress and displacement distributions in the vicinity of a crack are determined using a shear lag model. These are incorporated into an energy based cracking criterion to determine the favorability of crack formation. A progressive damage algorithm allows the inclusion of material softening effects and temperature-dependent material properties. The analysis is implemented by a computer code which gives predicted crack density and degraded laminate properties as functions of any thermomechanical load history. Extensive experimentation provides verification of the analysis. AS4/3501-6 graphite/epoxy laminates are manufactured with three different layups to investigate ply thickness and orientation effects. Thermal specimens are cooled to progressively lower temperatures down to -184 C. After conditioning the specimens to each temperature, cracks are counted on their edges using optical microscopy and in their interiors by sanding to incremental depths. Tensile coupons are loaded monotonically to progressively higher loads until failure. Cracks are counted on the coupon edges after each loading. A data fit to all available results provides input parameters for the analysis and shows them to be material properties, independent of geometry and loading. Correlation between experiment and analysis is generally very good under both thermal and mechanical loading, showing the methodology to be a powerful, unified tool. Delayed crack initiation observed in a few cases is attributed to a

  3. Numerical Simulation on Damage Mode Evolution in Composite Laminate

    Directory of Open Access Journals (Sweden)

    Jean-Luc Rebière

    2014-09-01

    Full Text Available The present work follows numerous numerical simulation on the stress field analysis in a cracked cross-ply laminate. These results lead us to elaborate an energy criterion. This criterion is based on the computation of the partial strain energy release rate associated with all the three damage types: transverse cracking, longitudinal cracking and delamination. The related criterion, linear fracture based approach, is used to predict and describe the initiation of the different damage mechanisms. With this approach the influence of the nature of the material constituent on the damage mechanism is computed. We also give an assessment of the strain energy release rates associated with each damage mode. This criterion checked on glass-epoxy and graphite-epoxy composite materials will now be used in future research on new bio-based composite in the laboratory.

  4. Analysis of laminated composite shells under internal pressure

    Science.gov (United States)

    Yuan, F. G.

    1991-01-01

    A closed form solution is presented that predicts the response of filament wound composite shells subjected to internal pressure. The material of the shell is assumed to be general cylindrically anisotropic. Based on the theory of cylindrical anisotropic elasticity coupled differential equations are developed using Lekhnitskii's stress function approach. Two composite systems, graphite/epoxy and glass/epoxy, are selected to demonstrate the influence of degree of material anisotropy and fiber orientations on the axial and induced twisting deformation. Detailed stress distributions of (45) off-axis unidirectional and (45/-45)s symmetric angle-ply fiber-reinforced laminated shells are shown to illustrate the effect of radius-to-thickness ratio and stacking sequence.

  5. Esthetic Rehabilitation of Anterior Teeth with Laminates Composite Veneers

    Directory of Open Access Journals (Sweden)

    Dino Re

    2014-01-01

    Full Text Available No- or minimal-preparation veneers associated with enamel preservation offer predictable results in esthetic dentistry; indirect additive anterior composite restorations represent a quick, minimally invasive, inexpensive, and repairable option for a smile enhancement treatment plan. Current laboratory techniques associated with a strict clinical protocol satisfy patients’ restorative and esthetic needs. The case report presented describes minimal invasive treatment of four upper incisors with laminate nanohybrid resin composite veneers. A step-by-step protocol is proposed for diagnostic evaluation, mock-up fabrication and trial, teeth preparation and impression, and adhesive cementation. The resolution of initial esthetic issues, patient satisfaction, and nice integration of indirect restorations confirmed the success of this anterior dentition rehabilitation.

  6. Esthetic rehabilitation of anterior teeth with laminates composite veneers.

    Science.gov (United States)

    Re, Dino; Augusti, Gabriele; Amato, Massimo; Riva, Giancarlo; Augusti, Davide

    2014-01-01

    No- or minimal-preparation veneers associated with enamel preservation offer predictable results in esthetic dentistry; indirect additive anterior composite restorations represent a quick, minimally invasive, inexpensive, and repairable option for a smile enhancement treatment plan. Current laboratory techniques associated with a strict clinical protocol satisfy patients' restorative and esthetic needs. The case report presented describes minimal invasive treatment of four upper incisors with laminate nanohybrid resin composite veneers. A step-by-step protocol is proposed for diagnostic evaluation, mock-up fabrication and trial, teeth preparation and impression, and adhesive cementation. The resolution of initial esthetic issues, patient satisfaction, and nice integration of indirect restorations confirmed the success of this anterior dentition rehabilitation.

  7. Discrete Material Buckling Optimization of Laminated Composite Structures considering "Worst" Shape Imperfections

    DEFF Research Database (Denmark)

    Henrichsen, Søren Randrup; Lindgaard, Esben; Lund, Erik

    2015-01-01

    Robust design of laminated composite structures is considered in this work. Because laminated composite structures are often thin walled, buckling failure can occur prior to material failure, making it desirable to maximize the buckling load. However, as a structure always contains imperfections...

  8. Quantitative Percussion Diagnostics For Evaluating Bond Integrity Between Composite Laminates

    Science.gov (United States)

    Poveromo, Scott Leonard

    Conventional nondestructive testing (NDT) techniques used to detect defects in composites are not able to determine intact bond integrity within a composite structure and are costly to use on large and complex shaped surfaces. To overcome current NDT limitations, a new technology was utilized based on quantitative percussion diagnostics (QPD) to better quantify bond quality in fiber reinforced composite materials. Experimental results indicate that this technology is capable of detecting 'kiss' bonds (very low adhesive shear strength), caused by the application of release agents on the bonding surfaces, between flat composite laminates bonded together with epoxy adhesive. Specifically, the local value of the loss coefficient determined from quantitative percussion testing was found to be significantly greater for a release coated panel compared to that for a well bonded sample. Also, the local value of the probe force or force returned to the probe after impact was observed to be lower for the release coated panels. The increase in loss coefficient and decrease in probe force are thought to be due to greater internal friction during the percussion event for poorly bonded specimens. NDT standards were also fabricated by varying the cure parameters of an epoxy film adhesive. Results from QPD for the variable cure NDT standards and lap shear strength measurements taken of mechanical test specimens were compared and analyzed. Finally, experimental results have been compared to a finite element analysis to understand the visco-elastic behavior of the laminates during percussion testing. This comparison shows how a lower quality bond leads to a reduction in the percussion force by biasing strain in the percussion tested side of the panel.

  9. Periodic and chaotic dynamics of composite laminated piezoelectric rectangular plate with one-to-two internal resonance

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The bifurcations and chaotic dynamics of a simply supported symmetric cross-ply composite lami- nated piezoelectric rectangular plate are studied for the first time, which are simultaneously forced by the transverse, in-plane excitations and the excitation loaded by piezoelectric layers. Based on the Reddy’s third-order shear deformation plate theory, the nonlinear governing equations of motion for the composite laminated piezoelectric rectangular plate are derived by using the Hamilton’s principle. The Galerkin’s approach is used to discretize partial differential governing equations to a two-degree- of-freedom nonlinear system under combined the parametric and external excitations. The method of multiple scales is employed to obtain the four-dimensional averaged equation. Numerical method is utilized to find the periodic and chaotic responses of the composite laminated piezoelectric rectangular plate. The numerical results indicate the existence of the periodic and chaotic responses in the aver- aged equation. The influence of the transverse, in-plane and piezoelectric excitations on the bifurca- tions and chaotic behaviors of the composite laminated piezoelectric rectangular plate is investigated numerically.

  10. Interlaminar tension strength of graphite/epoxy composite laminates

    Science.gov (United States)

    Shivakumar, Kunigal N.; Allen, Harold G.; Avva, Vishnu S.

    1994-01-01

    An L-shaped curved beam specimen and a tension loading fixture were proposed to measure the interlaminar tension strength of laminated and textile composites. The specimen size was 2 X 2 in. (51 X 51 mm). The use of a standard tension test machine and the introduction of load nearly at the specimen midthickness were the advantages of the proposed specimen. Modified Lekhnitskii and beam theory equations for calculating interlaminar stresses of an L-beam were verified by finite element analysis. The beam theory equation is simple and accurate for mean radius to thickness ratios greater than 1.5. The modified Lekhnitskii equations can be used for detailed stress field calculation. AS4/3501-6 graphite/epoxy unidirectional specimens with thicknesses of 16, 24, and 32 piles were fabricated and tested. The delamination initiation site agreed with the calculated maximum interlaminar tension stress location for all three thicknesses. Average interlaminar tension strengths of 16-, 24-, and 32-ply laminates were 47.6, 40.9, and 23.4 MPa, respectively.

  11. Irradiation effects in tungsten-copper laminate composite

    Science.gov (United States)

    Garrison, L. M.; Katoh, Y.; Snead, L. L.; Byun, T. S.; Reiser, J.; Rieth, M.

    2016-12-01

    Tungsten-copper laminate composite has shown promise as a structural plasma-facing component as compared to tungsten rod or plate. The present study evaluated the tungsten-copper composite after irradiation in the High Flux Isotope Reactor (HFIR) at temperatures of 410-780 °C and fast neutron fluences of 0.02-9.0 × 1025 n/m2, E > 0.1 MeV, 0.0039-1.76 displacements per atom (dpa) in tungsten. Tensile tests were performed on the composites, and the fracture surfaces were analyzed with scanning electron microscopy. Before irradiation, the tungsten layers had brittle cleavage failure, but the overall composite had 15.5% elongation at 22 °C. After only 0.0039 dpa this was reduced to 7.7% elongation, and no ductility was observed after 0.2 dpa at all irradiation temperatures when tensile tested at 22 °C. For elevated temperature tensile tests after irradiation, the composite only had ductile failure at temperatures where the tungsten was delaminating or ductile.

  12. Irradiation effects in tungsten-copper laminate composite

    Energy Technology Data Exchange (ETDEWEB)

    Garrison, L. M.; Katoh, Y.; Snead, L. L.; Byun, T. S.; Reiser, J.; Rieth, M.

    2016-12-01

    Tungsten-copper laminate composite has shown promise as a structural plasma-facing component as compared to tungsten rod or plate. The present study evaluated the tungsten-copper composite after irradiation in the High Flux Isotope Reactor (HFIR) at temperatures of 410-780°C and fast neutron fluences of 0.02-9.0×1025 n/m2, E>0.1 MeV, 0.0039-1.76 displacements per atom (dpa) in tungsten. Tensile tests were performed on the composites, and the fracture surfaces were analyzed with scanning electron microscopy. Before irradiation, the tungsten layers had brittle cleavage failure, but the overall composite had 15.5% elongation at 22°C. After only 0.0039 dpa this was reduced to 7.7% elongation, and no ductility was observed after 0.2 dpa at all irradiation temperatures when tensile tested at 22°C. For elevated temperature tensile tests after irradiation, the composite only had ductile failure at temperatures where the tungsten was delaminating or ductile.

  13. Influence of residual stresses on the tensile strength of composite-metal sandwich laminates

    Science.gov (United States)

    Herakovich, C. T.; Wong, D. M.

    1977-01-01

    The tensile strength of boron-epoxy/aluminum sandwich laminates is discussed relative to the residual thermal stresses generated by curing and bonding at elevated temperatures. It is shown that the sandwich laminates investigated exhibit three dinstinct modes of failure, depending upon the fiber orientation of the composite. Sandwich laminates with moderate to high percentage of 0-deg fibers exhibit early failures initiated by edge effect; laminates with moderate to high percentage of 90-deg fibers fail according to a first-ply failure criterion; laminates with moderate to high percentages of plus or minus 45 deg plies fail at strains equal to or greater than the failure strain of the corresponding all-composite laminate.

  14. Vibration, Stability, and Resonance of Angle-Ply Composite Laminated Rectangular Thin Plate under Multiexcitations

    Directory of Open Access Journals (Sweden)

    M. Sayed

    2013-01-01

    Full Text Available An analytical investigation of the nonlinear vibration of a symmetric cross-ply composite laminated piezoelectric rectangular plate under parametric and external excitations is presented. The method of multiple time scale perturbation is applied to solve the nonlinear differential equations describing the system up to and including the second-order approximation. All possible resonance cases are extracted at this approximation order. The case of 1 : 1 : 3 primary and internal resonance, where Ω3≅ω1, ω2≅ω1, and ω3≅3ω1, is considered. The stability of the system is investigated using both phase-plane method and frequency response curves. The influences of the cubic terms on nonlinear dynamic characteristics of the composite laminated piezoelectric rectangular plate are studied. The analytical results given by the method of multiple time scale is verified by comparison with results from numerical integration of the modal equations. Reliability of the obtained results is verified by comparison between the finite difference method (FDM and Runge-Kutta method (RKM. It is quite clear that some of the simultaneous resonance cases are undesirable in the design of such system. Such cases should be avoided as working conditions for the system. Variation of the parameters μ1, μ2, α7,β8, ω1, ω2, f1, f2 leads to multivalued amplitudes and hence to jump phenomena. Some recommendations regarding the different parameters of the system are reported. Comparison with the available published work is reported.

  15. Analysis of transient temperature field of the laminate composite membrane in space environment

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The on-orbit transient temperature of reflector laminate film was analyzed by using finite element method (FEM) . Numerical simulation was used by FEM software ANSYS. Results reveal that the temperature levels of the laminate composite membrane alternate greatly in the orbital period, which is about ±80℃. This range exceeds the material's operating temperature level. So it is necessary to put effective thermal control into effect to the laminate composite membrane. There is temperature gradient in the thickness direction of the laminate composite membrane: there is a light change in Kevlar/Epoxy layer. The temperature of the laminate composite membrane is obviously lower than the seam's temperature. Results provide reference to the thermal control of the inflatable reflector with high precision requirement.

  16. Fatigue life prediction and experiment research for composite laminates with circular hole

    Institute of Scientific and Technical Information of China (English)

    齐红宇; 温卫东; 孙联文

    2004-01-01

    Based on the fatigue prediction model of exponential function and Whitney-Nuismer(WN) criterion of static strength for the composite material laminate with a circular hole, the stress correct factor (β) was put forward and a new fatigue prediction model for composite material laminate was set up. T300/KH304, which is recently studied and is a high capability composite material, was used as the raw material. In order to gain the factorβ, the fatigue experiments of the laminates with holes in different diameters and the same ratio of width to diameter were conducted. The fatigue analysis and tests of the laminates with a hole 5 mm in diameter are carried out at different stress levels, and the results meet the engineering requirement. The simple, prompt and practical method is provided for the prediction of S-N curve of composite laminate with a circular hole.

  17. Fatigue damage mechanisms in boron-aluminium composite laminates

    Science.gov (United States)

    Dvorak, G. J.; Johnson, W. S.

    1980-01-01

    The relationship between fatigue and shakedown in metal matrix composites is investigated theoretically and experimentally for unidirectional and laminated 6061 Al-B materials. It is shown that no fatigue damage takes place if the applied stress range is such that the material remains elastic, or shakes down, i.e., resumes elastic cyclic straining after a small number of plastic strain cycles. Fatigue damage occurs only in specimens subjected to stress ranges which cause sustained cyclic plastic straining in the aluminum matrix. If the applied stress range is smaller than that required for fatigue failure, after about 10 to the 6th cycles a saturation damage state is reached which remains essentially unchanged with increasing number of cycles.

  18. Mode Mixity for Orthotropic Interface Delamination in Laminated Composites

    Institute of Scientific and Technical Information of China (English)

    FAN Xue-ling; SUN Qin; YUAN Mei-ni; Masanori Kikuchi

    2009-01-01

    The mode mixity is defined based on nonoscillatory strain energy release rate components of delamination between two different orthotropic materials to evaluate the delamination behavior of laminated composites.The result showes that the relative location of the delamination through the thickness influences the mode mixity in a relatively well-regulated way,and that the reinforcement directions of the adjacent plies along the delamination front have a more complicated impact on the mode mixity.This is caused by the bending/twist coupling and bending/bending coupling in the stress field at the crack tip for delamination between multidirectional plies,which completely modifies the stress and strain fields ahead of the crack tip.These kinds of couplings account for the non-uniform distribution of mode mixity values along the delamination front.Application of appropriate mode mixity values is necessary for accurate prediction of delamination growth.

  19. Synthesis and characterization of laminated Si/SiC composites

    Directory of Open Access Journals (Sweden)

    Salma M. Naga

    2013-01-01

    Full Text Available Laminated Si/SiC ceramics were synthesized from porous preforms of biogenous carbon impregnated with Si slurry at a temperature of 1500 °C for 2 h. Due to the capillarity infiltration with Si, both intrinsic micro- and macrostructure in the carbon preform were retained within the final ceramics. The SEM micrographs indicate that the final material exhibits a distinguished laminar structure with successive Si/SiC layers. The produced composites show weight gain of ≈5% after heat treatment in air at 1300 °C for 50 h. The produced bodies could be used as high temperature gas filters as indicated from the permeability results.

  20. Experimental Design on Laminated Veneer Lumber Fiber Composite: Surface Enhancement

    Science.gov (United States)

    Meekum, U.; Mingmongkol, Y.

    2010-06-01

    Thick laminate veneer lumber(LVL) fibre reinforced composites were constructed from the alternated perpendicularly arrayed of peeled rubber woods. Glass woven was laid in between the layers. Native golden teak veneers were used as faces. In house formulae epoxy was employed as wood adhesive. The hand lay-up laminate was cured at 150° C for 45 mins. The cut specimen was post cured at 80° C for at least 5 hours. The 2k factorial design of experimental(DOE) was used to verify the parameters. Three parameters by mean of silane content in epoxy formulation(A), smoke treatment of rubber wood surface(B) and anti-termite application(C) on the wood surface were analysed. Both low and high levels were further subcategorised into 2 sub-levels. Flexural properties were the main respond obtained. ANOVA analysis of the Pareto chart was engaged. The main effect plot was also testified. The results showed that the interaction between silane quantity and termite treatment is negative effect at high level(AC+). Vice versa, the interaction between silane and smoke treatment was positive significant effect at high level(AB+). According to this research work, the optimal setting to improve the surface adhesion and hence flexural properties enhancement were high level of silane quantity, 15% by weight, high level of smoked wood layers, 8 out of 14 layers, and low anti termite applied wood. The further testes also revealed that the LVL composite had superior properties that the solid woods but slightly inferior in flexibility. The screw withdrawn strength of LVL showed the higher figure than solid wood. It is also better resistance to moisture and termite attack than the rubber wood.

  1. Optimization Formulations for the Maximum Nonlinear Buckling Load of Composite Structures

    DEFF Research Database (Denmark)

    Lindgaard, Esben; Lund, Erik

    2011-01-01

    , benchmarked on a number of numerical examples of laminated composite structures for the maximization of the buckling load considering fiber angle design variables. The optimization formulations are based on either linear or geometrically nonlinear analysis and formulated as mathematical programming problems...... solved using gradient based techniques. The developed local criterion is formulated such it captures nonlinear effects upon loading and proves useful for both analysis purposes and as a criterion for use in nonlinear buckling optimization. © 2010 Springer-Verlag....

  2. Study on fabrication of smart FRP-OFBG composite laminates and their sensing properties

    Science.gov (United States)

    Wang, Yanlei; Zhou, Zhi; Ou, Jinping

    2007-01-01

    Fiber reinforced polymer (FRP) has gained much attention in civil engineering due to its high strength-to-weight and stiffness-to-weight ratios, corrosion resistance and good fatigue resistance. Optical Fiber Bragg Grating (OFBG) is now widely accepted as smart sensor due to its advantages of electric-magnetic resistance, small size, distributed sensing, durability, and so on. Combined the FRP with OFBG, new kind of smart FRP-OFBG composite laminates was developed. Fabrication method of the smart composite laminates was introduced in this paper. The study presented the basic principle of OFBG sensors. Then the strain and temperature sensing properties of the proposed smart FRP-OFBG composite laminates were experimentally studied on material test system and under hot water, respectively. The experimental results indicate the strain sensing properties of the smart FRP-OFBG composite laminates are nearly the same as that of bare OFBG, however, the temperature sensing abilities of the smart FRP-OFBG composite laminates are improved and the sensitivity coefficient is nearly 3.2 times as much as that of bare OFBG. The strain and temperature sensing precisions of the smart FRP-OFBG composite laminates are 1 μ\\Vegr and 0.03 °C, respectively. The smart FRYOFBG composite laminates are very proper for application in civil engineering.

  3. Micromechanics analysis of space simulated thermal stresses in composites. I - Theory and unidirectional laminates. II - Multidirectional laminates and failure predictions

    Science.gov (United States)

    Bowles, David E.; Griffin, O. H., Jr.

    1991-01-01

    A micromechanics analysis is used to study the effects of constituent properties on thermally induced stresses in continuous fiber reinforced composites. A finite element formulation is described, and results are presented for unidirectional carbon/epoxy laminates. It is shown that significant stresses develop in composites exposed to thermal excursions typical of spacecraft operating environments and that the fiber thermoelastic properties have a minimal effect on the magnitude of these stresses. The finite element micromechanics analysis is then extended to the study of multidirectional laminates using a simple global/local formulation. Damage initiation predictions are compared with experimental data, and factors controlling the initiation of damage are identified. Ways of improving the durability of composites are discussed.

  4. Probabilistic Modelling of Fatigue Life of Composite Laminates Using Bayesian Inference

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Kiureghian, Armen Der

    2014-01-01

    A probabilistic model for estimating the fatigue life of laminated composite plates subjected to constant-amplitude or variable-amplitude loading is developed. The model is based on lamina-level input data, making it possible to predict fatigue properties for a wide range of laminate configuratio...

  5. Load bearing enhancement of pin joined composite laminates using electrospun polyacrylonitrile nanofiber mats

    Directory of Open Access Journals (Sweden)

    J. Herwan

    2016-03-01

    Full Text Available Polyacrylonitrile (PAN nanofibers were produced by an electrospinning technique and directly deposited onto carbon fabric to improve the load bearing strength of pin joined composite laminates. Two types of specimens, virgin laminates and nano-modified laminates, were prepared. A modified carbon fiber reinforced polymer (CFRP laminate was fabricated by interleaving electrospun nanofibers at all of the interlayers of an eight-ply woven carbon fiber fabric. The load bearing test results of the pin joined laminates indicated the electrospun PAN nanofibers increased the load bearing strength by 18.9%. In addition, three point bending tests were also conducted to investigate the flexural modulus and flexural strength of both types of laminates. The flexural modulus and flexural strength also increased by 20.9% and 55.91%, respectively.

  6. Failure mode interaction in fiber reinforced laminated composites

    Science.gov (United States)

    Prabhakar, Pavana

    A novel computational modeling framework to predict the compressive strength of fiber reinforced polymer matrix composite (FRPC) laminates has been presented. The model development has been motivated by a set of experimental results on the compression response of two different FRPCs. The model accounts for failure mode interaction between kink-banding and interface fracture (or delamination), which are observed in the experimental results. To reduce the size of the computational model, those interfaces that are most susceptible to delamination are first determined through a free-edge stress analysis. Furthermore, 0-axis layers, which are passive in the failure process are represented through an equivalent homogenized model, but the microstructural features of the on-axis layers (zero plies) are retained in the computational model. The predictions of the model matched well with the experimental observations, and they were found to accurately account for failure mechanism interactions. Therefore, this model has the potential to replace the need to carry out large numbers of tests to obtain the compressive strength allowable for FRPC laminates, the latter allowable being an essential element in the design of lightweight FRPC aerostructures. Furthermore, the thesis presents a new computational model to predict fiber/matrix splitting failure, a failure mode that is frequently observed in in-plane tensile failure of FRPC's. By considering a single lamina, this failure mechanism was seamlessly modeled through the development of a continuum-decohesive nite element (CDFE). The CDFE was motivated by the variational multiscale cohesive method (VMCM) presented earlier by Rudraraju et al. (2010) at the University of Michigan. In the CDFE, the transition from a continuum to a non-continuum is modeled directly (physically) without resorting to enrichment of the shape functions of the element. Thus, the CDFE is a natural merger between cohesive elements and continuum elements. The

  7. Implementation of Improved Transverse Shear Calculations and Higher Order Laminate Theory Into Strain Rate Dependent Analyses of Polymer Matrix Composites

    Science.gov (United States)

    Zhu, Lin-Fa; Kim, Soo; Chattopadhyay, Aditi; Goldberg, Robert K.

    2004-01-01

    A numerical procedure has been developed to investigate the nonlinear and strain rate dependent deformation response of polymer matrix composite laminated plates under high strain rate impact loadings. A recently developed strength of materials based micromechanics model, incorporating a set of nonlinear, strain rate dependent constitutive equations for the polymer matrix, is extended to account for the transverse shear effects during impact. Four different assumptions of transverse shear deformation are investigated in order to improve the developed strain rate dependent micromechanics model. The validities of these assumptions are investigated using numerical and theoretical approaches. A method to determine through the thickness strain and transverse Poisson's ratio of the composite is developed. The revised micromechanics model is then implemented into a higher order laminated plate theory which is modified to include the effects of inelastic strains. Parametric studies are conducted to investigate the mechanical response of composite plates under high strain rate loadings. Results show the transverse shear stresses cannot be neglected in the impact problem. A significant level of strain rate dependency and material nonlinearity is found in the deformation response of representative composite specimens.

  8. Innovative design of composite structures: Axisymmetric deformations of unsymmetrically laminated cylinders loaded in axial compression

    Science.gov (United States)

    Hyer, M. W.; Paraska, P. J.

    1990-01-01

    The study focuses on the axisymmetric deformation response of unsymmetrically laminate cylinders loaded in axial compression by known loads. A geometrically nonlinear analysis is used. Though buckling is not studied, the deformations can be considered to be the prebuckling response. Attention is directed at three 16 layer laminates: a (90 sub 8/0 sub 8) sub T; a (0 sub 8/90 sub 8) sub T and a (0/90) sub 4s. The symmetric laminate is used as a basis for comparison, while the two unsymmetric laminates were chosen because they have equal but opposite bending-stretching effects. Particular attention is given to the influence of the thermally-induced preloading deformations that accompany the cool-down of any unsymmetric laminate from the consolidation temperature. Simple support and clamped boundary conditions are considered. It is concluded that: (1) The radial deformations of an unsymmetric laminate are significantly larger than the radial deformations of a symmetric laminate, although for both symmetric and unsymmetric laminates the large deformations are confined to a boundary layer near the ends of the cylinder; (2) For this nonlinear problem the length of the boundary layer is a function of the applied load; (3) The sign of the radial deformations near the supported end of the cylinder depends strongly on the sense (sign) of the laminate asymmetry; (4) For unsymmetric laminates, ignoring the thermally-induced preloading deformations that accompany cool-down results in load-induced deformations that are under predicted; and (5) The support conditions strongly influence the response but the influence of the sense of asymmetry and the influence of the thermally-induced preloading deformations are independent of the support conditions.

  9. On the drop-weight testing of alumina/aluminum laminated composites

    Indian Academy of Sciences (India)

    Mustafa Übeylı; R Orhan Yildirim; Bılgehan Ögel

    2005-10-01

    Laminated composites with ceramic front layers and metallic or composite backing layers have gained attractiveness as lightweight armours, as they exhibit the same ballistic performance with lower areal densities as compared to steels. Drop-weight testing (DWT) has potential for evaluating the low velocity impact behaviour of materials. This testing gives significant ideas and information about failure mechanisms and behaviour of materials under low velocity impact. In this study, DWT of alumina/aluminum laminated composites was done in order to investigate the effects of lamination type, density with respect to area and mechanical property of backing material on the low velocity ballistic performance of these composites. The experimental results showed that the laminated composite with ceramic front layer and aged-aluminum alloy as backing layer was the most effective among different investigated specimens against low velocity impact loads.

  10. Bioinspired Transparent Laminated Composite Film for Flexible Green Optoelectronics.

    Science.gov (United States)

    Lee, Daewon; Lim, Young-Woo; Im, Hyeon-Gyun; Jeong, Seonju; Ji, Sangyoon; Kim, Yong Ho; Choi, Gwang-Mun; Park, Jang-Ung; Lee, Jung-Yong; Jin, Jungho; Bae, Byeong-Soo

    2017-07-19

    Herein, we report a new version of a bioinspired chitin nanofiber (ChNF) transparent laminated composite film (HCLaminate) made of siloxane hybrid materials (hybrimers) reinforced with ChNFs, which mimics the nanofiber-matrix structure of hierarchical biocomposites. Our HCLaminate is produced via vacuum bag compressing and subsequent UV-curing of the matrix resin-impregnated ChNF transparent paper (ChNF paper). It is worthwhile to note that this new type of ChNF-based transparent substrate film retains the strengths of the original ChNF paper and compensates for ChNF paper's drawbacks as a flexible transparent substrate. As a result, compared with high-performance synthetic plastic films, such as poly(ethylene terephthalate), poly(ether sulfone), poly(ethylene naphthalate), and polyimide, our HCLaminate is characterized to exhibit extremely smooth surface topography, outstanding optical clarity, high elastic modulus, high dimensional stability, etc. To prove our HCLaminate as a substrate film, we use it to fabricate flexible perovskite solar cells and a touch-screen panel. As far as we know, this work is the first to demonstrate flexible optoelectronics, such as flexible perovskite solar cells and a touch-screen panel, actually fabricated on a composite film made of ChNF. Given its desirable macroscopic properties, we envision our HCLaminate being utilized as a transparent substrate film for flexible green optoelectronics.

  11. Analysis of Free Edge Stresses in Composite Laminates Using Higher Order Theories

    Directory of Open Access Journals (Sweden)

    Hamidreza Yazdani Sarvestani

    2014-01-01

    Full Text Available This paper presents the determination of the interlaminar stresses close to the free edges of general cross-ply composite laminates based on higher order equivalent single-layer theory (HESL. The laminates with finite dimensions were subjected to a bending moment, an axial force, and/or a torque for investigation. Full three-dimensional stresses in the interior and the boundary-layer regions were determined. The computed results were compared with those obtained from Reddy’s layerwise theory. It was found that HESL theory predicts precisely the interlaminar stresses near the free edges of laminates. Besides, high efficiency in terms of computational time is obtainable when HESL theory is used as compared with layerwise theory. Finally, various numerical results were presented for the cross-ply laminates. Also design guidelines were proposed to minimize the edge-effect problems in composite laminates.

  12. Investigation of Through-Thickness Stresses in Composite Laminates Using Layerwise Theory

    Directory of Open Access Journals (Sweden)

    Hamidreza Yazdani Sarvestani

    2013-01-01

    Full Text Available In this study, an analytical method is developed to exactly obtain the interlaminar stresses near the free edges of laminated composite plates under the bending moment based on the reduced form of elasticity displacement field for a long laminate. The analytical and numerical studies were performed based on the Reddy’s layerwise theory for the boundary layer stresses within cross-ply, symmetric, angle-ply, and general composite laminates. Finally, a variety of numerical results are presented for the interlaminar normal and shear stresses along the interfaces and through thickness of laminates near the free edges. The results showed high stress gradient of interlaminar normal and shear stresses near the edges of laminates.

  13. Prediction of process induced shape distortions and residual stresses in large fibre reinforced composite laminates

    DEFF Research Database (Denmark)

    Nielsen, Michael Wenani

    The present thesis is devoted to numerical modelling of thermomechanical phenomena occurring during curing in the manufacture of large fibre reinforced polymer matrix composites with thick laminate sections using vacuum assisted resin transfer moulding (VARTM). The main application of interest...

  14. Graphite/epoxy Composite Laminates with Co-cured Interlaminar Damping Layers

    Science.gov (United States)

    Pereira, J. Michael

    1993-01-01

    Damped composite laminates were fabricated by co-curing viscoelastic damping film with graphite/epoxy prepreg plies. The dynamic response of the damped plates was measured using an impulse response technique and compared with the response of similar undamped laminates. Modal damping was computed from the frequency response data. Micrographs of the damped laminates showed that the damping layers retained their integrity during the fabrication process. The layers significantly increased the damping in the composite laminates. The use of the constrained viscoelastic film as an integral part of composite structures appears to be a feasible approach to passive vibration control. Composite plates manufactured with co-cured damping layers may have commercial applications in cases where light weight, strength, and vibration and noise reduction are important considerations.

  15. Free Vibration Analysis of Laminated Composite Beams Using Differential Quadrature Method

    Institute of Scientific and Technical Information of China (English)

    冯丽娟; 钟宏志; 郝照平; 吴德隆

    2002-01-01

    A higher-order theory for laminated composite beams is used to study the free vibration of laminated composite beams, and the differential quadrature method is employed to obtain the numerical solution of the governing differential equations. Free vibration analysis of beams with rectangular cross-section for various combinations of end conditions is studied. The results show that the differential quadrature method is reliable and accurate compared with other available results.

  16. The ultimate state of polymeric materials and laminated and fibrous composites under asymmetric high-cycle loading

    Science.gov (United States)

    Golub, V. P.; Pogrebniak, A. D.; Kochetkova, E. S.

    2008-01-01

    The prediction of the high-cycle fatigue strength of polymeric and composite materials in asymmetric loading is considered. The problem is solved on the basis of a nonlinear model of ultimate state allowing us to describe all typical forms of the diagrams of ultimate stresses. The material constants of the model are determined from the results of fatigue tests in symmetric reversed cycling, in a single fatigue test with the minimum stress equal to zero, and in a short-term strength test. The fatigue strength characteristics of some polymers, glass-fiber laminates, glass-fiber-reinforced plastics, organic-fiber-reinforced plastics, and wood laminates in asymmetric tension-compression, bending, and torsion have been calculated and approved experimentally.

  17. Ballistic impact damage and penetration mechanics of fiber-reinforced composite laminates

    Science.gov (United States)

    Patts, Henry Michael

    2000-10-01

    Experimental and theoretical studies were performed to characterize and model the processes of damage evolution and resulting penetration failure of graphite fiber-reinforced epoxy resin composite laminates ("structural grade") under ballistic impact. In contrast to the local yielding demonstrated by ductile isotropic materials, the penetration failure of fiber-reinforced composites produced extensive fragmentation of material with multiple modes of damage propagation such as "delamination," "interfiber matrix splitting," "transverse fiber cuts," and "through-the-thickness plugging." Due to the formation of damage zones in three-dimensional scale, the increase in target thickness raised the amount of kinetic energy absorption for full penetration in a "non-linear" fashion in fiber composites unlike the linear correlation for isotropic material such as polycarbonate and aluminum. Interfiber matrix splitting and delamination were found to be the first sign of structural deterioration occurring far below V50 and precede transverse cutting of fibers and plugging. The development of interfiber splitting into delamination of composites is explained by relying on the contact mechanics of a spherical indentor. Matrix splits on adjacent plies formed one pair of geometrical "wedges" at the ply interface, resulting in a delamination zone connected through an "isthmus." Contained in this free ply region, stress concentration readily led to transverse cutting (approximately at 85 percent of the V50) of plies when longitudinal stress of the reinforcing fibers reaches a critical level for fracture. The observed distribution of the damage leading to transverse fiber cuts was modeled by idealizing a circular target panel of staircase laminate into three zones with different values of bending stiffness due to the progression of damage. In "three-zone" model, the energy absorbed by the panel were represented in three forms of potential energy; surface free energy due to delamination

  18. Bounding the current in nonlinear conducting composites

    Science.gov (United States)

    Milton, Graeme W.; Serkov, Sergey K.

    2000-06-01

    Suppose a three-dimensional composite of two nonlinear conducting phases mixed in fixed proportions is subject to a fixed average electric field. What values can the average current take as the microstructure varies over all configurations? What microstructures produce the maximum or minimum current flow? Which microstructures are best for guiding the current in a given direction? Here, following the compensated compactness method of Tartar (1977: Estimation de coefficients homogénéisés. In: Glowinski, R., Lions, J.-L. (Eds.), Computer Methods in Applied Sciences and Engineering, Springer-Verlag Lecture Notes in Mathematics 704. Springer-Verlag, Berlin, pp. 136-212) we show how one can obtain remarkably tight bounds on the average current flow. In many, but not all cases, we find that simple laminate structures produce the maximum or minimum current flow, and are best for guiding the current in a given direction. Sometimes it is advantageous to orient the layer surfaces parallel (rather than orthogonal) to the direction of the applied field to generate the minimum current flow in that direction.

  19. Nonlinear resonance converse magnetoelectric effect modulated by voltage for the symmetrical magnetoelectric laminates under magnetic and thermal loadings

    Science.gov (United States)

    Zhou, Hao-Miao; Liu, Hui; Zhou, Yun; Hu, Wen-Wen

    2016-12-01

    Based on the tri-layer symmetrical magnetoelectric laminates, a equivalent circuit for the nonlinear resonance converse magnetoelectric coupling effect is established. Because the nonlinear thermo-magneto-mechanical constitutive equations of magnetostrictive material were introduced, a converse magnetoelectric coefficient model was derived from the equivalent circuit, which can describe the influence of bias electric field, bias magnetic field and ambient temperature on the resonance converse magnetoelectric coupling effect. Especially, the model can well predict the modulation effect of bias electric field/voltage on the magnetism of magnetoelectric composite or the converse magnetoelectric coefficient, which is absolutely vital in applications. Both of the converse magnetoelectric coefficient and the resonance frequency predicted by the model have good agreements with the existing experimental results in qualitatively and quantitatively, and the validity of the model is confirmed. On this basis, according to the model, the nonlinear trends of the resonance converse magnetoelectric effect under different bias voltages, bias magnetic fields and ambient temperatures are predicted. From the results, it can be found that the bias voltage can effectively modulate the curve of the resonance converse magnetoelectric coefficient versus bias magnetic field, and then change the corresponding optimal bias magnetic field of the maximum converse magnetoelectric coefficient; with the increasing volume ratio of piezoelectric layers, the modulation effect of bias voltage becomes more obvious; under different bias magnetic fields, the modulation effect of bias voltage on the converse magnetoelectric effect has nonvolatility in a wide temperature region.

  20. Characterization of delamination onset and growth in a composite laminate

    Science.gov (United States)

    Obrien, T. K.

    1981-01-01

    The onset and growth of delaminations in unnotched (+ or - 30/+ or - 30/90/90 bar) sub S graphite epoxy laminates is described quantitatively. These laminates, designed to delaminate at the edges under tensile loads, were tested and analyzed. Delamination growth and stiffness loss were monitored nondestructively. Laminate stiffness decreased linearly with delamination size. The strain energy release rate, G, associated with delamination growth, was calculated from two analyses. A critical G for delamination onset was determined, and then was used to predict the onset of delaminations in (+45 sub n/-45 sub n/o sub n/90 sub n) sub s (n=1,2,3) laminates. A delamination resistance curve (R curve) was developed to characterize the observed stable delamination growth under quasi static loading. A power law correlation between G and delamination growth rates in fatigue was established.

  1. Wave Propagation Analysis in Composite Laminates Containing a Delamination Using a Three-Dimensional Spectral Element Method

    Directory of Open Access Journals (Sweden)

    Fucai Li

    2012-01-01

    Full Text Available A three-dimensional spectral element method (SEM was developed for analysis of Lamb wave propagation in composite laminates containing a delamination. SEM is more efficient in simulating wave propagation in structures than conventional finite element method (FEM because of its unique diagonal form of the mass matrix. Three types of composite laminates, namely, unidirectional-ply laminates, cross-ply laminates, and angle-ply laminates are modeled using three-dimensional spectral finite elements. Wave propagation characteristics in intact composite laminates are investigated, and the effectiveness of the method is validated by comparison of the simulation results with analytical solutions based on transfer matrix method. Different Lamb wave mode interactions with delamination are evaluated, and it is demonstrated that symmetric Lamb wave mode may be insensitive to delamination at certain interfaces of laminates while the antisymmetric mode is more suited for identification of delamination in composite structures.

  2. Laminated exfoliated graphite composite-metal compositions for fuel cell flow field plate or bipolar plate applications

    Science.gov (United States)

    Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

    2014-05-20

    An electrically conductive laminate composition for fuel cell flow field plate or bipolar plate applications. The laminate composition comprises at least a thin metal sheet having two opposed exterior surfaces and a first exfoliated graphite composite sheet bonded to the first of the two exterior surfaces of the metal sheet wherein the exfoliated graphite composite sheet comprises: (a) expanded or exfoliated graphite and (b) a binder or matrix material to bond the expanded graphite for forming a cohered sheet, wherein the binder or matrix material is between 3% and 60% by weight based on the total weight of the first exfoliated graphite composite sheet. Preferably, the first exfoliated graphite composite sheet further comprises particles of non-expandable graphite or carbon in the amount of between 3% and 60% by weight based on the total weight of the non-expandable particles and the expanded graphite. Further preferably, the laminate comprises a second exfoliated graphite composite sheet bonded to the second surface of the metal sheet to form a three-layer laminate. Surface flow channels and other desired geometric features can be built onto the exterior surfaces of the laminate to form a flow field plate or bipolar plate. The resulting laminate has an exceptionally high thickness-direction conductivity and excellent resistance to gas permeation.

  3. Nonlinear dynamic behaviors of clamped laminated shallow shells with one-to-one internal resonance

    Science.gov (United States)

    Abe, Akira; Kobayashi, Yukinori; Yamada, Gen

    2007-07-01

    This paper investigates one-to-one internal resonance of laminated shallow shells with rigidly clamped edges. It is assumed that the natural frequencies ω2 and ω3 of two asymmetric (second and third) vibration modes have the relationship ω2≈ ω3. The displacements are expressed by using eigenvectors for linear vibration modes calculated by the Ritz method. Applying Galerkin's procedure to the equation of motion, nonlinear differential equations are derived. By considering the first vibration mode in addition to the two asymmetric vibration modes, quadratic nonlinear terms expressing the interaction between the asymmetric and the first modes appear in the differential equations. Shooting method is used to obtain the steady-state response when the driving frequency Ω is near ω2. The dynamic characteristics of the shells with the internal resonance are discussed.

  4. Stress Waves in Composite Laminates Excited by Transverse Plane Shock Waves

    Directory of Open Access Journals (Sweden)

    G.R. Liu

    1996-01-01

    Full Text Available A simple 1-dimensional model is presented to investigate elastic stress waves in composite laminates excited by underwater explosion shocks. The focus is on the elastic dynamic stress fields in the composite laminate immediately after the action of the shock wave. In this model, the interaction between the laminate and the water is taken into account, and the effects of the laminate-water interaction on the stress wave fields in the laminate are investigated. In the formulation of the model, wave fields in the laminate and the water are the first obtained in the frequency domain and then transferred into the time domain using the Fourier transform techniques. A quadrature technique is used to deal with the Fourier transform integrals in which the integrands have very sharp peaks on the integral axis. Numerical examples for stress waves in a steel plate and a glass reinforced plastic sandwich laminate are presented. The technique and the results presented in this article may be used in the design of ship hull structures subjected to underwater explosions.

  5. Effects of Delaminations on the Damped Dynamic Characteristics of Composite Laminates: Mechanics and Experiments

    Science.gov (United States)

    Saravanos, D. A.; Hopkins, D. A.

    1995-01-01

    Analytical and experimental work is presented on the damped free-vibration of delaminated laminates and beams. A laminate theory is developed where the unknown kinematic perturbations induced by a delamination crack are treated as additional degrees of freedom. The generalized stiffness, inertia and damping matrices of the laminate are formulated. An analytical solution is developed for the prediction of natural frequencies, modes and modal damping in composite beams with delamination cracks. Evaluations of the mechanics on various cantilever beams with a central delamination are performed. Experimental results for the modal frequencies and damping of composite beams with a single delamination are also presented and correlations between analytical predictions and measured data are shown. The effects of delamination vary based on crack size, laminate configuration, and mode order. The implications of the mechanics in developing delamination detection techniques are also discussed.

  6. Global blending optimization of laminated composites with discrete material candidate selection and thickness variation

    DEFF Research Database (Denmark)

    Sørensen, Søren N.; Stolpe, Mathias

    2015-01-01

    to a distinct choice among predefined numbers of candidates. The laminate thickness is variable but the number of plies must be integer. We solve the convex mixed binary non-linear programming problem by an outer approximation cutting-plane method augmented with a few heuristics to accelerate the convergence...

  7. Effect of stacking sequence on the coefficients of mutual influence of composite laminates

    Science.gov (United States)

    Dupir (Hudișteanu, I.; Țăranu, N.; Axinte, A.

    2016-11-01

    Fiber reinforced polymeric (FRP) composites are nowadays widely used in engineering applications due to their outstanding features, such as high specific strength and specific stiffness as well as good corrosion resistance. A major advantage of fibrous polymeric composites is that their anisotropy can be controlled through suitable choice of the influencing parameters. The unidirectional fiber reinforced composites provide much higher longitudinal mechanical properties compared to the transverse ones. Therefore, composite laminates are formed by stacking two or more laminas, with different fiber orientations, as to respond to complex states of stresses. These laminates experience the effect of axial-shear coupling, which is caused by applying normal or shear stresses, implying shear or normal strains, respectively. The normal-shear coupling is expressed by the coefficients of mutual influence. They are engineering constants of primary interest for composite laminates, since the mismatch of the material properties between adjacent layers can produce interlaminar stresses and/or plies delamination. The paper presents the variation of the in-plane and flexural coefficients of mutual influence for three types of multi-layered composites, with different stacking sequences. The results are obtained using the Classical Lamination Theory (CLT) and are illustrated graphically in terms of fiber orientations, for asymmetric, antisymmetric and symmetric laminates. Conclusions are formulated on the variation of these coefficients, caused by the stacking sequence.

  8. Deflection of Cross-Ply Composite Laminates Induced by Piezoelectric Actuators

    Directory of Open Access Journals (Sweden)

    Chi-Sheng Lin

    2010-01-01

    Full Text Available The coupling effects between the mechanical and electric properties of piezoelectric materials have drawn significant attention for their potential applications as sensors and actuators. In this investigation, two piezoelectric actuators are symmetrically surface bonded on a cross-ply composite laminate. Electric voltages with the same amplitude and opposite sign are applied to the two symmetric piezoelectric actuators, resulting in the bending effect on the laminated plate. The bending moment is derived by using the classical laminate theory and piezoelectricity. The analytical solution of the flexural displacement of the simply supported composite plate subjected to the bending moment is solved by using the plate theory. The analytical solution is compared with the finite element solution to show the validation of present approach. The effects of the size and location of the piezoelectric actuators on the response of the composite laminate are presented through a parametric study. A simple model incorporating the classical laminate theory and plate theory is presented to predict the deformed shape of the simply supported laminate plate.

  9. A comparison of graphite/epoxy tape laminates and 2-D braided composites mechanical properties

    Science.gov (United States)

    Minguet, Pierre J.

    1995-01-01

    A comparison of the mechanical properties of unidirectional composite tape laminates and of two-dimensional triaxially braided composite was conducted. The tape laminate layups were designed to match the percentage of axial fibers and the angle of the bias tows in the braided composite. The materials system used for the laminates is AS4/3501-6 which was chosen as the closest available match to As4/1895 used for the braids. The strength and stiffness properties measured here include tension, open-hole tension, filled-hole tension, compression and open-hole compression, all of these in both the longitudinal and transverse direction. Results show that the longitudinal modulus of both material forms is quite similar, but that the transverse modulus of the braids is lower. In terms of strength, the longitudinal unnotched strength of the braids is lower than that of the laminates, while the transverse strength is significantly lower. For both strength and stiffness, the crimp in the bias tows of the braid is probably the main cause for reduced properties. On the other hand, a very significant increase in open-hole and filled-hole tension strength was observed for the braids compared to the tape laminates. However, this was not observed in compression where all the braid properties are lower than for the laminates.

  10. The Effective AC Response of Nonlinear Composites

    Institute of Scientific and Technical Information of China (English)

    WEI En-Bo; GU Guo-Qing

    2001-01-01

    A perturbative approach is used to study the AC response of nonlinear composite media, which obey a current-field relation of the form J = σ E + χ|E|2 E with components having nonlinear response at finite frequencies. For a sinusoidal applied field, we extend the local potential in terms of sinusoidal components at fundamental frequency and high-order harmonic frequencies to treat the nonlinear composites. For nonlinear composite media vith a low concentrations of spherical inclusions, we give the formulae of the nonlinear effective AC susceptibility χ*3ω at the third harmonic frequency.

  11. Development of Improved LOX-Compatible Laminated Gasket Composite

    Science.gov (United States)

    1966-08-01

    NITROGEN TEMPERATURE WITH TFE LAMINATING RESIN Specimen Thickness, Cycle Energy Absorption, No. Type Resin in. No. in.-lb/in.3 101-B DuPont TFE 0.055...GASKETS AT LIQUID NITROGEN TEMPERATURE WITH HALON G-80 LAMINATING RESIN Specimen Thickness, Cycle Energy Absorption, No. Type Resin in. No. in.-lb/in. 3 107...Thickness, Cycle Energy Absorption, No. Type Resin in. No. in.-lb/in. 3 101-A DuPont TFE 0.069 1 41.2 2 42.9 10 38.6 102-A DuPont TFE 0.073 1 40.3 2 37.0

  12. NUMERICAL ANALYSIS OF DELAMINATION GROWTH FOR STIFFENED COMPOSITE LAMINATED PLATES

    Institute of Scientific and Technical Information of China (English)

    白瑞祥; 陈浩然

    2004-01-01

    A study of postbuckling and delamination propagation behavior in delaminated stiffened composite plates was presented. A methodology was proposed for simulating the multi-failure responses, such as initial and postbuckling, delamination onset and propagation, etc. A finite element analysis was conducted on the basis of the Mindlin first order shear effect theory and the von-Krmn nonlinear deformation assumption. The total energy release rate used as the criteria of delamination growth was estimated with virtual crack closure technique (VCCT). A self-adaptive grid moving technology was adopted to model the delamination growth process. Moreover, the contact effect along delamination front was also considered during the numerical simulation process. By some numerical examples, the influence of distribution and location of stiffener, configuration and size of the delamination, boundary condition and contact effect upon the delamination growth behavior of the stiffened composite plates were investigated. The method and numerical conclusion provided should be of great value to engineers dealing with composite structures.

  13. Randomized controlled split-mouth clinical trial of direct laminate veneers with two micro-hybrid resin composites

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Kalk, Warner; Ozcan, M.; Ozcan, Mutlu

    Objectives: This randomized, split-mouth clinical study evaluated the survival rate of direct laminate veneers made of two resin-composite materials. Methods: A total of 23 patients (mean age: 52.4 years old) received 96 direct composite laminate veneers using two micro-hybrid composites in

  14. Randomized controlled split-mouth clinical trial of direct laminate veneers with two micro-hybrid resin composites

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Kalk, Warner; Ozcan, M.; Ozcan, Mutlu

    2012-01-01

    Objectives: This randomized, split-mouth clinical study evaluated the survival rate of direct laminate veneers made of two resin-composite materials. Methods: A total of 23 patients (mean age: 52.4 years old) received 96 direct composite laminate veneers using two micro-hybrid composites in combinat

  15. Application of martensitic SMA alloys as passive dampers of GFRP laminated composites

    Directory of Open Access Journals (Sweden)

    M. Bocciolone

    2013-01-01

    Full Text Available This paper describes the application of SMA (Shape Memory Alloy materials to enhance the passive damping of GFRP (Glass Fiber Reinforced Plastic laminated composite. The SMA has been embedded as reinforcement in the GFRP laminated composite and a SMA/GFRP hybrid composite has been obtained. Two SMA alloys have been studied as reinforcement and characterized by thermo-mechanical tests. The architecture of the hybrid composite has been numerically optimized in order to enhance the structural damping of the host GFRP laminated, without significant changes of the specific weight and of the flexural stiffness. The design and the resultant high damping material are interesting and will be useful in general for applications related to passive damping. The application to a new designed lateral horn of railway collector of the Italian high speed trains is discussed.

  16. Nonlinear oscillations of laminated plates using an accurate four-node rectangular shear flexible material finite element

    Indian Academy of Sciences (India)

    Gajbir Singh; G Venkateswara Rao

    2000-08-01

    The objective of the present paper is to investigate the large amplitude vibratory behaviour of unsymmetrically laminated plates. For this purpose, an efficient and accurate four-node shear flexible rectangular material finite element(MFE) with six degrees offreedom per node (three displacements $(u;v;w)$ along the $x, y$ and axes, two rotations ($\\theta_x$ and $\\theta_y$) about and axes and twist $(\\theta_{xy})$) is developed. The element assumes bi-cubic polynomial distribution with sixteen generalized undetermined coefficients for the transverse displacement. The fields for section rotations $\\theta_x$ and $\\theta_y$, and in-plane displacements and are derived using moment-shear equilibrium and in-plane equilibrium equations of composite strips along the - and -axes. The displacement field so derived not only depends on the element coordinates but is a function of extensional, bending-extensional coupling, bending and transverse shear stiffness as well. The element stiffness and mass matrices are computed numerically by employing 3 × 3 Gauss-Legendre product rules. The element is found to be free of shear locking and does not exhibit any spurious modes. In orderto compute the nonlinearfrequencies, linear mode shape corresponding to the fundamental frequency is assumed as the spatial distribution and nonlinear finite element equations are reduced to a single nonlinear second-order differential equation. This equation is solved by employing the direct numerical integration method. A series of numerical examples are solved to demonstrate the efficacy of the proposed element.

  17. Transmission of ultrasonic waves at oblique incidence to composite laminates with spring-type interlayer interfaces.

    Science.gov (United States)

    Ishii, Yosuke; Biwa, Shiro

    2015-11-01

    The transmission characteristics of ultrasonic waves at oblique incidence to composite laminates are analyzed theoretically by the stiffness matrix method. The analysis takes into account the presence of thin resin-rich regions between adjacent plies as spring-type interfaces with normal and shear stiffnesses. The amplitude transmission coefficient of longitudinal wave through a unidirectional laminate immersed in water is shown to be significantly influenced by the frequency, the interlayer interfacial stiffnesses, and the incident angle. Using Floquet's theorem, the dispersion relation of the infinitely extended laminate structure is calculated and compared to the transmission coefficient of laminates of finite thickness. This reveals that the ranges of frequency and interfacial stiffnesses where the Floquet waves lie in the band-gaps agree well with those where the transmission coefficient of the finite layered structure is relatively small, indicating that the band-gaps appear even in the laminate with a finite number of plies. The amplitude transmission coefficient for an 11-ply carbon-epoxy unidirectional composite laminate is experimentally obtained for various frequencies and incident angles. The low-transmission zones observed in the experimental results, which are due to the critical angle of the quasi-longitudinal wave and the Bragg reflection, are shown to be favorably compared with the theory.

  18. Finite element modeling of small-scale tapered wood-laminated composite poles with biomimicry features

    Science.gov (United States)

    Cheng Piao; Todd F. Shupe; R.C. Tang; Chung Y. Hse

    2008-01-01

    Tapered composite poles with biomimicry features as in bamboo are a new generation of wood laminated composite poles that may some day be considered as an alternative to solid wood poles that are widely used in the transmission and telecommunication fields. Five finite element models were developed with ANSYS to predict and assess the performance of five types of...

  19. Embedding Piezoresistive Pressure Sensors to Obtain Online Pressure Profiles Inside Fiber Composite Laminates

    Directory of Open Access Journals (Sweden)

    Maryam Kahali Moghaddam

    2015-03-01

    Full Text Available The production of large and complex parts using fiber composite materials is costly due to the frequent formation of voids, porosity and waste products. By embedding different types of sensors and monitoring the process in real time, the amount of wastage can be significantly reduced. This work focuses on developing a knowledge-based method to improve and ensure complete impregnation of the fibers before initiation of the resin cure. Piezoresistive and capacitive pressure sensors were embedded in fiber composite laminates to measure the real-time the pressure values inside the laminate. A change of pressure indicates resin infusion. The sensors were placed in the laminate and the resin was infused by vacuum. The embedded piezoresistive pressure sensors were able to track the vacuum pressure in the fiber composite laminate setup, as well as the arrival of the resin at the sensor. The pressure increase due to closing the resin inlet was also measured. In contrast, the capacitive type of sensor was found to be inappropriate for measuring these quantities. The following study demonstrates real-time monitoring of pressure changes inside the fiber composite laminate, which validate the use of Darcy’s law in porous media to control the resin flow during infusion.

  20. Embedding piezoresistive pressure sensors to obtain online pressure profiles inside fiber composite laminates.

    Science.gov (United States)

    Moghaddam, Maryam Kahali; Breede, Arne; Brauner, Christian; Lang, Walter

    2015-03-27

    The production of large and complex parts using fiber composite materials is costly due to the frequent formation of voids, porosity and waste products. By embedding different types of sensors and monitoring the process in real time, the amount of wastage can be significantly reduced. This work focuses on developing a knowledge-based method to improve and ensure complete impregnation of the fibers before initiation of the resin cure. Piezoresistive and capacitive pressure sensors were embedded in fiber composite laminates to measure the real-time the pressure values inside the laminate. A change of pressure indicates resin infusion. The sensors were placed in the laminate and the resin was infused by vacuum. The embedded piezoresistive pressure sensors were able to track the vacuum pressure in the fiber composite laminate setup, as well as the arrival of the resin at the sensor. The pressure increase due to closing the resin inlet was also measured. In contrast, the capacitive type of sensor was found to be inappropriate for measuring these quantities. The following study demonstrates real-time monitoring of pressure changes inside the fiber composite laminate, which validate the use of Darcy's law in porous media to control the resin flow during infusion.

  1. Effect of Material Property of Interply Film on the Delamination in Laminated Composites 8

    Institute of Scientific and Technical Information of China (English)

    WeiFENG; QiaoHUANG

    1999-01-01

    The delamination is one of the main failure modes in laminated composites.In order to suppress and /or delay it,considerable research has been devoted to the reduction of the interlaminar stresses at the interfaces between two different plies.This paper studies the effect of isotropic layers placed at ply interface on the interlaminar behaviour of the angle-ply laminated composites.The results of the experiment and numerical analysis show that the material properties of interply film have strong influence on the interlaminar behaviour of laminated composites.In order to suppress delamination,the material of interply film has to been selected carefully due to the fact that different matrials have different results .SOme materials may increase the stress values at the interfaces.Some materials may reduce the stress concertration.

  2. Micromechanics-Based Progressive Failure Analysis of Composite Laminates Using Different Constituent Failure Theories

    Science.gov (United States)

    Moncada, Albert M.; Chattopadhyay, Aditi; Bednarcyk, Brett A.; Arnold, Steven M.

    2008-01-01

    Predicting failure in a composite can be done with ply level mechanisms and/or micro level mechanisms. This paper uses the Generalized Method of Cells and High-Fidelity Generalized Method of Cells micromechanics theories, coupled with classical lamination theory, as implemented within NASA's Micromechanics Analysis Code with Generalized Method of Cells. The code is able to implement different failure theories on the level of both the fiber and the matrix constituents within a laminate. A comparison is made among maximum stress, maximum strain, Tsai-Hill, and Tsai-Wu failure theories. To verify the failure theories the Worldwide Failure Exercise (WWFE) experiments have been used. The WWFE is a comprehensive study that covers a wide range of polymer matrix composite laminates. The numerical results indicate good correlation with the experimental results for most of the composite layups, but also point to the need for more accurate resin damage progression models.

  3. An approach for the reliability based design optimization of laminated composites

    Science.gov (United States)

    Holdorf Lopez, Rafael; Lemosse, Didier; Souza de Cursi, José Eduardo; Rojas, Jhojan; El-Hami, Abdelkhalak

    2011-10-01

    This article aims at optimizing laminated composite plates taking into account uncertainties in the structural dimensions. As laminated composites require a global optimization tool, the Particle Swarm Optimization (PSO) method is employed. A new Reliability Based Design Optimization (RBDO) methodology based on safety factors is presented and coupled with PSO. Such safety factors are derived from the Karush-Kuhn-Tucker optimality conditions of the reliability index approach and eliminate the need for reliability analysis in RBDO. The plate weight minimization is the objective function of the optimization process. The results show that the coupling of the evolutionary algorithm with the safety-factor method proposed in this article successfully performs the RBDO of laminated composite structures.

  4. Effect of Fiber Orientation Angle on the Failure Mode of Pin Jointed Laminated Composite Plates

    Directory of Open Access Journals (Sweden)

    Kadir TURAN

    2010-02-01

    Full Text Available In this study, the major aim is to investigate change effects of fiber orientation angles on the failure loads and failure modes for the pin jointed laminated composite plates. In the analysis, laminated composite plates with epoxy matrix resin reinforced unidirectional carbon fibers are used. The ply arrangements are chosen [?0]4 and ?; fiber reinforced angle changes from 00 to 900 with 150 increments. The failure load and failure mode are analyzed experimentally and numerically. In the numerical analysis Ansys program is used. In the program, material properties are degraded using APDL code which is written for progressive failure analysis and contains Hashin failure criteria for laminated composite plates. In the experimental study, the maximum failure load for [150]4 laminae cofiguration, 749.917 N and minimum failure load for [600]4, 467.483 N laminae configuration are obtained. A good agreement between experimental and numerical solution is obtained.

  5. Constructing of cure monitoring system with piezoelectric ceramics for composite laminate

    Science.gov (United States)

    Oshima, Nobuo; Inoue, Kouichi; Motogi, Shinya; Fukuda, Takehito

    2003-08-01

    The cure monitoring system with piezoelectric ceramics is constructed. An embedded type piezoelectric ceramics sensor with flat lead wires is developed. And the piezoelectric ceramics is embedded into composite laminate. A dummy piezoelectric ceramics is set in the autoclave oven. The impedance of the piezoelectric ceramics which is embedded in the composite laminate and that of the dummy piezoelectric ceramics are measured by a LCR meter. The piezoelectric ceramics have strong temperature dependency. The temperature dependency of the impedance of piezoelectric ceramics is corrected by the information from the dummy piezoelectric ceramics. A dielectric sensor is also embedded in the composite laminate as a reference sensor for the degree of cure. The change in calculated cure index shows good correspondence with change in the log ion viscosity which is measured by the dielectric cure monitoring sensor.

  6. Investigation of Effect of Carbon Fibres on the Mechanical Properties of the Hybrid Composite Laminate

    Directory of Open Access Journals (Sweden)

    Vidyashankar B V

    2014-06-01

    Full Text Available In this work Fabric made of woven carbon, glass along with epoxy resins are used to make composite laminate. Average resin fraction on weight basis after curing was 45%. The different types of specimens are prepared with variable percentage of carbon fibres. The mechanical tests such as Tensile test, compression test, flexural test and impact tests are conducted over the specimens and the results are evaluated which indicates that the increase in carbon content increases the mechanical properties of the composite laminate .

  7. Damage assessment of laminated composite beam structures using damage locating vector (DLV) method

    Institute of Scientific and Technical Information of China (English)

    T. VO-DUY[1,3; N. NGUYEN-MINH[1,3; H. DANG-TRUNG[1,3; A. TRAN-VIET[2,3; T. NGUYEN-THOI[1,3

    2015-01-01

    In this paper, the damage locating vector employed to locate multiple damage sites in laminated (DLV) method using normalized cumulative energy (nce) is composite beam structures. Numerical simulations of two laminated composite beams are employed to investigate several damage scenarios in which the degradation of elements is modeled by the reduction in the longitudinal Young's modulus and transverse Young's modulus of beam layers. The results show that the DLV method gives good performance for this kind of structure.

  8. Delamination detection in composite laminates using dispersion change based on mode conversion of Lamb waves

    Science.gov (United States)

    Okabe, Yoji; Fujibayashi, Keiji; Shimazaki, Mamoru; Soejima, Hideki; Ogisu, Toshimichi

    2010-11-01

    A new ultrasonic propagation system has been constructed using macrofiber composite (MFC) actuators and fiber Bragg grating (FBG) sensors. The MFCs and FBGs can be integrated into composite laminates because of their small size and high fracture strain. The developed system can send and receive broadband Lamb waves. In this research, this system was used to detect delamination damage in composite laminates. First, the multiple modes of Lamb waves in a carbon-fiber-reinforced plastic (CFRP) quasi-isotropic laminate were identified by transmitting and receiving the symmetric and antisymmetric modes separately. Then, the mode conversions at both tips of a delamination were investigated through an experiment and a two-dimensional finite element analysis (FEA). A new delamination detection method was proposed on the basis of the mode conversions, and experiments were carried out on laminates with an artificial delamination. When antisymmetric modes were excited, the frequency dispersion of the received A1 mode changed, depending on the delamination length owing to the mode conversion between the A1 mode and the S0 mode. This phenomenon was confirmed through the FEA and these results prove that this new method is effective in detecting a delamination in CFRP laminates.

  9. A Model of the Fatigue Life Distribution of Composite Laminates Based on Their Static Strength Distribution

    Institute of Scientific and Technical Information of China (English)

    Wu Fuqiang; Yao Weixing

    2008-01-01

    The reasons of the static strength dispersion and the fatigue life dispersion of composite laminates are analyzed in this article.It is concluded that the inner original defects,which derived from the manufacturing process of composite laminates,are the common and major reason of causing the random distributions of the static strength and the fatigue life.And there is a correlative relation between the two distributions.With the study of statistical relationship between the fatigue loading and the fatigue life in the uniform confidence level and the same survival rate S-N curves of material,the relationship between the static strength distribution and the fatigue life distribution through a material S-N curve model has been obtained.And then the model which is used to describe the distributions of fatigue life of composites,based on their distributions of static strength,is set up.This model reasonably reflects the effects of the inner original defects on the static strength dispersion and on the fatigue life dispersion of composite laminates.The experimental data of three kinds of composite laminates are employed to verify this model,and the results show that this model can predict the random distributions of fatigue life for composites under any fatigue loads fairly well.

  10. Performance of smart piezoelectric transducers for structural health monitoring on composite laminates in cryogenic environments

    Science.gov (United States)

    Tseng, Kevin K.; Tinker, Michael L.; Lassiter, John O.; Wang, Liangsheng

    2004-07-01

    An important way of increasing the payload in a reusable launch vehicle (RLV) is to replace heavy metallic materials by lightweight composite laminates. Engineers and scientists have studied many metallic materials thoroughly, due to the long history of practical usage in many aerospace and aeronautical structures. Compared to metallic materials, composite laminates are a relatively new material and therefore require more attention to ensure the safety and reliability. Among various parts and systems of the RLV, this study focuses on tanks containing cryogenic fuel. Historically, aluminum alloys have been used as the materials to construct fuel tanks for launch vehicles. To replace aluminum alloys with composite laminates or honeycomb materials, engineers have to make sure that the composites are free of defects before, during, and after launch. In addition to robust design and manufacturing procedures, the performance of the composite structures needs to be evaluated constantly. In recent years, the impedance-based health monitoring technique has shown its promise in many applications. This technique makes use of the special properties of smart piezoelectric materials to identify the change of material properties due to the nucleation and progression of damage. A major advantage of this technique is that the procedure is nondestructive in nature and does not perturb the properties and performance of the materials and structures. This paper reports the results of applying the impedance-based nondestructive testing technique to the damage identification of composite laminates at cryogenic temperature. These materials have potential application for fuel tanks in future RLV"s.

  11. CHARACTERISATION OF EPOXY BASED E-GLASS / CARBON REINFORCED POLYMER COMPOSITE LAMINATES SUBJECTED TO LOW VELOCITY IMPACT TEST (DROP WEIGHT

    Directory of Open Access Journals (Sweden)

    Dr.H.K.SHIVANAND

    2013-05-01

    Full Text Available The purpose of this research work is to investigate experimentally the Drop weight Impact response of epoxy matrixed e-glass and carbon reinforced polymer laminated composites. Impact tests had been conducted to characterize the type and extent of damage observed in composite laminates configured for varying thickness.

  12. Development and utilization of composite honeycomb and solid laminate reference standards for aircraft inspections.

    Energy Technology Data Exchange (ETDEWEB)

    Roach, Dennis Patrick; Rackow, Kirk A.

    2004-06-01

    The FAA's Airworthiness Assurance NDI Validation Center, in conjunction with the Commercial Aircraft Composite Repair Committee, developed a set of composite reference standards to be used in NDT equipment calibration for accomplishment of damage assessment and post-repair inspection of all commercial aircraft composites. In this program, a series of NDI tests on a matrix of composite aircraft structures and prototype reference standards were completed in order to minimize the number of standards needed to carry out composite inspections on aircraft. Two tasks, related to composite laminates and non-metallic composite honeycomb configurations, were addressed. A suite of 64 honeycomb panels, representing the bounding conditions of honeycomb construction on aircraft, was inspected using a wide array of NDI techniques. An analysis of the resulting data determined the variables that play a key role in setting up NDT equipment. This has resulted in a set of minimum honeycomb NDI reference standards that include these key variables. A sequence of subsequent tests determined that this minimum honeycomb reference standard set is able to fully support inspections over the full range of honeycomb construction scenarios found on commercial aircraft. In the solid composite laminate arena, G11 Phenolic was identified as a good generic solid laminate reference standard material. Testing determined matches in key velocity and acoustic impedance properties, as well as, low attenuation relative to carbon laminates. Furthermore, comparisons of resonance testing response curves from the G11 Phenolic NDI reference standard was very similar to the resonance response curves measured on the existing carbon and fiberglass laminates. NDI data shows that this material should work for both pulse-echo (velocity-based) and resonance (acoustic impedance-based) inspections.

  13. The role of embedded sensors in damage assessment in composite laminates

    Science.gov (United States)

    Park, Chun; Peters, Kara; Zikry, Mohammed

    2010-03-01

    Various densities of optical fibers are embedded into a total of eighty woven, graphite fiber-epoxy composite laminates, for which the response to low velocity impacts are evaluated. The goal of this work is to determine the role of hostsensor interaction on the lifetime of the host material system. The woven composites are subjected to multiple impacts at 14.5 J until perforation of the specimen. We obtain the energy dissipated by the laminate and the maximum contact force between the impactor laminate for each strike. From these experimental data we calculate the statistical distribution of the total energy dissipated at failure as a function of embedded optical fiber density. The total dissipated energy, a measure of the specimen lifetime, decreased with increasing embedded optical fiber density, however remained constant after a threshold density was reached. The total maximum contact force per specimen, a measure of the specimen stiffness, continued to decrease with the number of embedded optical fibers.

  14. Predicting the Failure Behavior of Textile Composite Laminates by Using a Multi-Scale Correlating Approach

    Science.gov (United States)

    Deng, Yan; Chen, Xiuhua; Wang, Hai

    2015-12-01

    This paper investigates the elastic and failure behavior of textile composite laminates by using an analytical multi-scale correlating approach. The analyses are performed under the four scale levels, i.e. the laminate scale, representative unit cell (RUC) scale, tow architecture scale and fiber/matrix scale levels. The correlation between different scales is derived based on the continuum mechanics and homogenization method from which the stress and strain fields in multiple scales can be obtained concurrently. Effective modulus and ultimate failure strengths of different textile composite (plain weave, twill weave and satin weave) laminates are predicted solely from the corresponding constituent properties, braid geometrical parameters and lay-up. The damage and failure mechanisms at the constituent level are also determined by the micromechanical failure criteria. All the predicted results compare favorably with available experimental data. Parametric studies are also performed to examine the effect of various mechanical and geometrical parameters on the resulting mechanical properties.

  15. Multi-Material and Thickness Optimization Utilizing Casting Filters for Laminated Composite Structures

    DEFF Research Database (Denmark)

    Sørensen, Rene; Lund, Erik

    2013-01-01

    This extended abstract presents a new parameterization for performing discrete material and thickness optimization of laminated composite structures. The parameterization is based on the work by Sørensen and Lund 2013, where we present a reformulation of the original parameterization. The reformu......This extended abstract presents a new parameterization for performing discrete material and thickness optimization of laminated composite structures. The parameterization is based on the work by Sørensen and Lund 2013, where we present a reformulation of the original parameterization....... The reformulation eliminates the need for having explicit constraint for ensuring that intermediate void does not appear in between layers of the laminate. This is achieved by utilizing a filtering technique known as a casting constraint from traditional topology optimization with isotropic materials....

  16. 3D Progressive Damage Modeling for Laminated Composite Based on Crack Band Theory and Continuum Damage Mechanics

    Science.gov (United States)

    Wang, John T.; Pineda, Evan J.; Ranatunga, Vipul; Smeltzer, Stanley S.

    2015-01-01

    A simple continuum damage mechanics (CDM) based 3D progressive damage analysis (PDA) tool for laminated composites was developed and implemented as a user defined material subroutine to link with a commercially available explicit finite element code. This PDA tool uses linear lamina properties from standard tests, predicts damage initiation with an easy-to-implement Hashin-Rotem failure criteria, and in the damage evolution phase, evaluates the degradation of material properties based on the crack band theory and traction-separation cohesive laws. It follows Matzenmiller et al.'s formulation to incorporate the degrading material properties into the damaged stiffness matrix. Since nonlinear shear and matrix stress-strain relations are not implemented, correction factors are used for slowing the reduction of the damaged shear stiffness terms to reflect the effect of these nonlinearities on the laminate strength predictions. This CDM based PDA tool is implemented as a user defined material (VUMAT) to link with the Abaqus/Explicit code. Strength predictions obtained, using this VUMAT, are correlated with test data for a set of notched specimens under tension and compression loads.

  17. Composite Laminate With Coefficient of Thermal Expansion Matching D263 Glass

    Science.gov (United States)

    Robinson, David; Rodini, Benjamin

    2012-01-01

    The International X-ray Observatory project seeks to make an X-ray telescope assembly with 14,000 flexible glass segments. The glass used is commercially available SCHOTT D263 glass. Thermal expansion causes the mirror to distort out of alignment. A housing material is needed that has a matching coefficient of thermal expansion (CTE) so that when temperatures change in the X-ray mirror assembly, the glass and housing pieces expand equally, thus reducing or eliminating distortion. Desirable characteristics of this material include a high stiffness/weight ratio, and low density. Some metal alloys show promise in matching the CTE of D263 glass, but their density is high compared to aluminum, and their stiffness/weight ratio is not favorable. A laminate made from carbon fiber reinforced plastic (CFRP) should provide more favorable characteristics, but there has not been any made with the CTE matching D263 Glass. It is common to create CFRP laminates of various CTEs by stacking layers of prepreg material at various angles. However, the CTE of D263 glass is 6.3 ppm/ C at 20 C, which is quite high, and actually unachievable solely with carbon fiber and resin. A composite laminate has been developed that has a coefficient of thermal expansion identical to that of SCHOTT D263 glass. The laminate is made of a combination of T300 carbon fiber, Eglass, and RS3C resin. The laminate has 50% uni-T300 plies and 50% uni-E-glass plies, with each fiber-layer type laid up in a quasi-isotropic laminate for a total of 16 plies. The fiber volume (percent of fiber compared to the resin) controls the CTE to a great extent. Tests have confirmed that a fiber volume around 48% gives a CTE of 6.3 ppm/ C. This is a fairly simple composite laminate, following well established industry procedures. The unique feature of this laminate is a somewhat unusual combination of carbon fiber with E-glass (fiberglass). The advantage is that the resulting CTE comes out to 6.3 ppm/ C at 20 C, which matches D

  18. Characterization and Formability of Titanium/Aluminum Laminate Composites Fabricated by Hot Pressing

    Science.gov (United States)

    Qin, Liang; Wang, Hui; Cui, Shengqiang; Wu, Qian; Fan, Minyu; Yang, Zonghui; Tao, Jie

    2017-07-01

    The Ti/Al laminate composites were prepared by hot pressing to investigate the forming performance due to the corresponding potential applications in both the aerospace and auto industry. The bonding interface morphology and element distributions were characterized by SEM and EDS. The phase constituent was detected by XRD. It was observed that these composites presented good bonding interfaces between Ti and Al layers, and no low-sized voids and intermetallic compounds formed at the interface. In addition, the formability of these laminate composites was studied by the uniaxial tension tests, the limit drawing ratio (LDR) and the forming limit curve (FLC) experiments, respectively. The results indicated that the flow stress increased along with the strain rate increment. A constitutive equation was developed for deformation behavioral description of these laminate composites. The LDR value was 1.8, and the most susceptible region to present cracks was located at the punch profile radius. The forming limit curve of the laminate composites was located between the curves of titanium and aluminum and intersected with the major strain line at approximately 0.31. The macroscopic cracks of the FLC sample demonstrated a saw-toothed crack feature.

  19. Three-dimensional hybrid-stress finite element analysis of composite laminates with cracks and cutouts

    Science.gov (United States)

    Wang, S. S.

    1985-01-01

    A three-dimensional hybrid-stress finite element analysis of composite laminates containing cutouts and cracks is presented. Fully three-dimensional, hexahedral isoparametric elements of the hybrid-stress model are formulated on the basis of the Hellinger-Reissner variational principle. Traction-free edges, cutouts, and crack surfaces are modeled by imposition of exact traction boundary conditions along element surfaces. Special boundary and surface elements are constructed by introducing proper constraints on assumed stress functions. The Lagrangian multiplier technique is used to enforce ply-interface continuity conditions in hybrid bimaterial composite elements for modeling the interface region in a composite laminate. Two examples are given to illustrate the capability of the present method of approach: (1) the well-known delamination problem in an angle-ply laminate, and (2) the important problem of a composite laminate containing a circular hole. Results are presented in detail for each case. Implications of interlaminar and intralaminar crack initiation, growth and fracture in composites containing cracks and cutouts are discussed.

  20. Evaluation of in-plane shear test methods for composite material laminates

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-lei; HAO Qing-duo; OU Jin-ping

    2007-01-01

    In-plane shear properties of composite material laminates are very important in structural design of composite material. Four commonly used in-plane shear test methods were introduced in this paper. In order to study the differences of various shear test methods, two ASTM standard in-plane shear test methods for composite material laminates were experimentally investigated. They are ±45℃ tensile shear test (ASTM D3518) and V-notched rail shear test (ASTM D7078). Five types of composite material laminates composed of E-glass fiber fabric and vinyl ester resin were utilized, whose stacking sequences are [0]3s, [0/90]3s, [CSM/0/90]2s, [±45]3s and [(0/90)2/(±45)2/(0/90)2]s, respectively. The test results indicate that the±45℃ tensile shear test can predict shear moduli of composite material laminates accurately. However, the predictions of shear strength using±45℃ tensile shear test are significantly lower than those of V-notched rail shear test.

  1. DELAMINATION FORMATION AND DELAMINATION PROPAGATION OF COMPOSITE LAMINATES UNDER COMPRESSIVE FATIGUE LOADING

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Fatigue tests of the smooth composite laminates and the notched composite laminates under compressive cyclic loading have been carried out. The damage mechanism is discussed and analyzed. Damage evolution is monitored using stiffness decay. From these tests, it is found that the initial delamination occurs at the free boundary of smooth specimens, or the notch boundary of notched specimens, subjected to the compression-compression cyclic load. A point of view in relation to two-phases of compression fatigue delamination of composites is proposed, namely, compression-compression delamination consists of the delamination formation phase and the delamination propagation, and there is a "damage transition point" to separate this two-phases. Furthermore, an empirical modulus degradation formula and its parameters fitting method are presented. According to the test data handling results, it is shown that this formula is univocal and can fit the test data conveniently. In addition, two kinds of new anti-buckling devices are designed for these tests. At last, the E-N curves, the D-N curves and the S-N curve of the smooth carbon fiber reinforced composite laminates of T300/648C are determined to predict the fatigue life of the notched composite laminate. And the E-N curve of the notched specimens at the given load ratio R=10 and minimum load P min=-0.45 kN is also measured to verify the estimated result of fatigue life.

  2. Laminate Analyses, Micromechanical Creep Response, and Fatigue Behavior of Polymer Matrix Composite Materials.

    Science.gov (United States)

    1982-12-01

    FATIGUE BEHAVIOR of POLYMER MATRIX COMPOSITE MATERIALS , 4 " .’* .. . . ". ... .. ... . . ~December 1982 41 .. FINAL REPORT .Army Research Office I I...DEPARTMENT REPORT UWME-DR-201-108-1 LAMINATE ANALYSES, MICROMECHANICAL CREEP RESPONSE, AND FATIGUE BEHAVIOR OF POLYMER MATRIX COMPOSITE MATERIALS...Behavior of Polymer Matrix Composite 16 Sept. 1979 - 30 Nov. 1982 Materials 6 PERFORMING ORG. REPORT NUMBER UWME-DR-201-108-1 7. AUTHOR(.) S. CONTRACT

  3. Scaling of low-velocity impact for symmetric composite laminates

    Science.gov (United States)

    Sankar, Bhavani V.

    1992-01-01

    The equations governing the problem of low-velocity impact of a simply supported rectangular midplane-symmetric laminated plate are nondimensionalized such that the problem is defined in terms of five dimensionless parameters. A parametric study using the Graeco-Latin Factorial Plan is performed. Semi-empirical formulas for maximum impact force, impact duration, and maximum back surface strains are obtained. It is found that some of the simple impact models provide the bounds for the case of impact on a finite extent plate. A one parameter model is derived for impacts of short duration.

  4. Enhancing buckling performance of perforated composite laminates by manipulating fiber direction using a genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hee Keun [Andong National University, Andong (Korea, Republic of); Rowlands, Robert E. [University of Wisconsin-Madison, Madison (United States)

    2015-09-15

    To maximize buckling loads of composite laminates, optimization is carried out using a Genetic algorithm (GA) in conjunction with finite element analysis. A perforated laminated composite plate is used for buckling analysis. The geometry is discretized into solid three dimensional twenty node isoparametric layered composite elements developed for this study. Fiber orientations of each element and individual plies are controlled independently by the genetic algorithm, which is especially advantageous for complex problems including many design variables. This approach for composite buckling produces more enhanced results than conventional methods, such as changing the stacking sequence of various rectilinear orthotropic plies with different fiber orientations, different ply thicknesses or different local fiber densities. Additionally, it can be used in diverse areas from sensitive local buckling to global stability of structures. The genetic algorithm, finite element analysis and eigen buckling analysis are numerically combined into a composite optimization code, COMBO20. The successful performance of the proposed approach is demonstrated with an example.

  5. Structural properties of laminated Douglas fir/epoxy composite material

    Energy Technology Data Exchange (ETDEWEB)

    Spera, D.A. (National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center); Esgar, J.B. (Sverdrup Technology, Inc., Cleveland, OH (USA)); Gougeon, M.; Zuteck, M.D. (Gougeon Bros., Bay City, MI (USA))

    1990-05-01

    This publication contains a compilation of static and fatigue and strength data for laminated-wood material made from Douglas fir and epoxy. Results of tests conducted by several organizations are correlated to provide insight into the effects of variables such as moisture, size, lamina-to-lamina joint design, wood veneer grade, and the ratio of cyclic stress to steady stress during fatigue testing. These test data were originally obtained during development of wood rotor blades for large-scale wind turbines of the horizontal-axis (propeller) configuration. Most of the strength property data in this compilation are not found in the published literature. Test sections ranged from round cylinders 2.25 in. in diameter to rectangular slabs 6 in. by 24 in. in cross section and approximately 30 ft long. All specimens were made from Douglas fir veneers 0.10 in. thick, bonded together with the WEST epoxy system developed for fabrication and repair of wood boats. Loading was usually parallel to the grain. Size effects (reduction in strength with increase in test volume) are observed in some of the test data, and a simple mathematical model is presented that includes the probability of failure. General characteristics of the wood/epoxy laminate are discussed, including features that make it useful for a wide variety of applications. 9 refs.

  6. Structural properties of laminated Douglas fir/epoxy composite material

    Science.gov (United States)

    Spera, David A.; Esgar, Jack B.; Gougeon, Meade; Zuteck, Michael D.

    1990-01-01

    This publication contains a compilation of static and fatigue strength data for laminated-wood material made from Douglas fir and epoxy. Results of tests conducted by several organizations are correlated to provide insight into the effects of variables such as moisture, size, lamina-to-lamina joint design, wood veneer grade, and the ratio of cyclic stress to steady stress during fatigue testing. These test data were originally obtained during development of wood rotor blades for large-scale wind turbines of the horizontal-axis (propeller) configuration. Most of the strength property data in this compilation are not found in the published literature. Test sections ranged from round cylinders 2.25 in. in diameter to rectangular slabs 6 by 24 in. in cross section and approximately 30 ft. long. All specimens were made from Douglas fir veneers 0.10 in. thick, bonded together with the WEST epoxy system developed for fabrication and repair of wood boats. Loading was usually parallel to the grain. Size effects (reduction in strength with increase in test volume) are observed in some of the test data, and a simple mathematical model is presented that includes the probability of failure. General characteristics of the wood/epoxy laminate are discussed, including features that make it useful for a wide variety of applications.

  7. Modeling and Chaotic Dynamics of the Laminated Composite Piezoelectric Rectangular Plate

    Directory of Open Access Journals (Sweden)

    Minghui Yao

    2014-01-01

    Full Text Available This paper investigates the multipulse heteroclinic bifurcations and chaotic dynamics of a laminated composite piezoelectric rectangular plate by using an extended Melnikov method in the resonant case. According to the von Karman type equations, Reddy’s third-order shear deformation plate theory, and Hamilton’s principle, the equations of motion are derived for the laminated composite piezoelectric rectangular plate with combined parametric excitations and transverse excitation. The method of multiple scales and Galerkin’s approach are applied to the partial differential governing equation. Then, the four-dimensional averaged equation is obtained for the case of 1 : 3 internal resonance and primary parametric resonance. The extended Melnikov method is used to study the Shilnikov type multipulse heteroclinic bifurcations and chaotic dynamics of the laminated composite piezoelectric rectangular plate. The necessary conditions of the existence for the Shilnikov type multipulse chaotic dynamics are analytically obtained. From the investigation, the geometric structure of the multipulse orbits is described in the four-dimensional phase space. Numerical simulations show that the Shilnikov type multipulse chaotic motions can occur. To sum up, both theoretical and numerical studies suggest that chaos for the Smale horseshoe sense in motion exists for the laminated composite piezoelectric rectangular plate.

  8. Effect of Ultrasonic Versus Manual Cementation on the Fracture Strength of Resin Composite Laminates

    NARCIS (Netherlands)

    Ozcan, M.; Mese, A.

    2009-01-01

    This study evaluated the effect of conventional versus ultrasonic cementation techniques on the fracture strength of resin composite laminates. In addition, the failure modes were assessed. Window-type preparations I mm above the cemento-enamel junction were made on intact human maxillary central in

  9. Effect of Ultrasonic Versus Manual Cementation on the Fracture Strength of Resin Composite Laminates

    NARCIS (Netherlands)

    Ozcan, M.; Mese, A.

    2009-01-01

    This study evaluated the effect of conventional versus ultrasonic cementation techniques on the fracture strength of resin composite laminates. In addition, the failure modes were assessed. Window-type preparations I mm above the cemento-enamel junction were made on intact human maxillary central in

  10. Scattering of the fundamental anti-symmetric Lamb wave at delaminations in composite laminates.

    Science.gov (United States)

    Ng, Ching-Tai; Veidt, Martin

    2011-03-01

    An analysis of the scattering characteristics of the fundamental anti-symmetric (A(0)) Lamb wave at a delamination in a quasi-isotropic composite laminate is presented. Analytical solutions for this problem do not exist due to the anisotropic nature and multilayer characteristics of composite laminates. This study uses a three-dimensional finite element (FE) method and experimental measurements to provide physical insight into the scattering phenomena. Good agreement is found between simulations and experimental measurements. The results show that the A(0) Lamb wave scattering at a delamination in composite laminates is much more complicated than the scattering at a defect in isotropic plates. Scatter amplitudes and scatter directivity distributions depend on the delamination size to wavelength ratio and the through-thickness location of the delamination damage. The study also investigates the feasibility of the common experimental practice of simulating delamination damage by bonding masses to the surface of composite laminates for guided wave damage detection and characterization methodologies verifications. The results suggest that care is required to use bonded masses to simulate delamination damage for verifying and optimizing damage characterization techniques. In summary, the results of the investigation help to further advance the use of the A(0) Lamb wave for damage detection and characterization.

  11. Design Optimization of Laminated Composite Structures with Many Local Strength Criteria

    DEFF Research Database (Denmark)

    Lund, Erik

    2012-01-01

    This paper presents different strategies for handling very many local strength criteria in structural optimization of laminated composites. Global strength measures using Kreisselmeier-Steinhauser or p-norm functions are introduced for patch-wise parameterizations, and the efficiency of the methods...

  12. Ply-based Optimization of Laminated Composite Shell Structures under Manufacturing Constraints

    DEFF Research Database (Denmark)

    Sørensen, Rene; Lund, Erik

    2012-01-01

    be performed on the basis of different materials, and/or consist of discrete selection of the same orthotropic material with different orientations of the fibers. The problem considered is the optimization of a general laminated composite shell structure with respect to maximum stiffness (minimum compliance...

  13. A numerical study on interacting damage mechanisms in FRP laminated composite plates

    NARCIS (Netherlands)

    Ahmed, A.; Sluys, L.J.

    2013-01-01

    Experimental testing and numerical analysis often travel in tandem in a design process. Recent advances in novel numerical techniques to simulate mesh objective crack propagation offer a great potential for accurate and efficient damage analysis of composite laminates. This paper presents a numerica

  14. Multi-Material and Thickness Optimization Utilizing Casting Filters for Laminated Composite Structures

    DEFF Research Database (Denmark)

    Sørensen, Rene; Lund, Erik

    2013-01-01

    This extended abstract presents a new parameterization for performing discrete material and thickness optimization of laminated composite structures. The parameterization is based on the work by Sørensen and Lund 2013, where we present a reformulation of the original parameterization....... The reformulation eliminates the need for having explicit constraint for ensuring that intermediate void does not appear in between layers of the laminate. This is achieved by utilizing a filtering technique known as a casting constraint from traditional topology optimization with isotropic materials....

  15. Simulating Initial and Progressive Failure of Open-Hole Composite Laminates under Tension

    Science.gov (United States)

    Guo, Zhangxin; Zhu, Hao; Li, Yongcun; Han, Xiaoping; Wang, Zhihua

    2016-06-01

    A finite element (FE) model is developed for the progressive failure analysis of fiber reinforced polymer laminates. The failure criterion for fiber and matrix failure is implemented in the FE code Abaqus using user-defined material subroutine UMAT. The gradual degradation of the material properties is controlled by the individual fracture energies of fiber and matrix. The failure and damage in composite laminates containing a central hole subjected to uniaxial tension are simulated. The numerical results show that the damage model can be used to accurately predicte the progressive failure behaviour both qualitatively and quantitatively.

  16. Characteristics of magnetic force control device with magnetostrictive and piezoelectric laminate composite

    Science.gov (United States)

    Ueno, Toshiyuki; Qiu, Jinhao; Tani, Junji

    2003-08-01

    A magnetic force control device with laminate composite of giant magnetostrictive material (GMM) and piezo-electric material (PZT) is proposed. This magnetic force control is based on inverse magnetostrictive effect of a magnetic material, whereby the variation of stress applied on the material is converted to that of magnetic force via magnetic circuits. For the purpose of realizing the method in practical applications, disks of GMM and PZT are laminated to control the stress of GMM by electric field on PZT. Due to the capacitive properties of PZT, the device requires little electric energy hence generates no heat to maintain constant force. Furthermore compared with conventional electromagnetics, the device can be fabricated easily and in small size to be suitable for microactuators. This paper presents the principle of the magnetic force control by the lamination of GMM and PZT and investigates the static and dynamic characteristics of several devices to demonstrate their capabilities of the magnetic force control.

  17. Dynamic-mechanical response of graphite/epoxy composite laminates and neat resin

    Science.gov (United States)

    Yang, P.; Carlsson, L.; Sternstein, S. S.

    1983-01-01

    Dynamic mechanical measurement results are presented for the case of carbon fiber-reinforced, epoxy matrix composite laminates subjected to loading perpendicular to the lamination plane, as well as for neat epoxy resin under the same conditions, where temperatures ranged between 20 and 200 C and deformation levels lie within the linear viscoelastic region. In-phase and out-of-phase stiffnesses are found to become superposed, forming master curves that cover a 12-decade frequency range. The application of a master curve scaling procedure shows that the in-phase stiffness has the same shape, and out-of-phase stiffness has the same dispersion, for all laminates irrespective of stacking sequence and are, in turn, nearly identical to those for the neat epoxy resin. An empirical function is found for the relaxation modulus which, when converted to a dynamic modulus, yields good overall agreement for both of the dynamic stiffness components as a function of frequency.

  18. Testing and modeling of damages in composite laminates subject to low velocity impact

    Directory of Open Access Journals (Sweden)

    Al-Hadrayi Ziadoon M. R, Zhang Yunlai, Zhou Chuwei

    2016-01-01

    Full Text Available In recent years, composite materials were used extensively in the most important industries, especially in aerospace industries and aircraft structures due to its high strength, high stiffness, resistance of corrosion, and lightweight. The problem is how to choose the perfect design for composite laminates. And study the effects of modeling of the stacking sequences of composite laminates on failure modes (delamination, matrix cracking, and fiber failure under the test of low velocity impact. This paper has validating to the experimental results that has published. The composite used was carbon fiber /epoxy (CFRE, (UD ASTM/D6641 as three groups [A, B, C]. It had same material system. The difference was only in stacking sequences as random design. These models were simulated numerically by the commercial software implemented into the FEM/ABAQUS 6.9.1 with subroutine file (VUMAT a user-define 3D damage model. The results had good agreement with experimental results.

  19. A simple higher order shear deformation theory for mechanical behavior of laminated composite plates

    Science.gov (United States)

    Adim, Belkacem; Daouadji, Tahar Hassaine; Rabahi, Aberezak

    2016-06-01

    In the present study, the static, buckling, and free vibration of laminated composite plates is examined using a refined shear deformation theory and developed for a bending analysis of orthotropic laminated composite plates. These models take into account the parabolic distribution of transverse shear stresses and satisfy the condition of zero shear stresses on the top and bottom surfaces of the plates. The most interesting feature of this theory is that it allows for parabolic distributions of transverse shear stresses across the plate thickness and satisfies the conditions of zero shear stresses at the top and bottom surfaces of the plate without using shear correction factors. The number of independent unknowns in the present theory is four, as against five in other shear deformation theories. In the analysis, the equation of motion for simply supported thick laminated rectangular plates is obtained through the use of Hamilton's principle. The accuracy of the analysis presented is demonstrated by comparing the results with solutions derived from other higher order models and with data found in the literature. It can be concluded that the proposed theory is accurate and simple in solving the static, the buckling, and free vibration behaviors of laminated composite plates.

  20. A PREDICTIVE APPROACH TO THE IN-PLANE MECHANICAL PROPERTIES OF STITCHED COMPOSITE LAMINATES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This contribution attempts to model the alteration of the in-plane elastic properties in laminates caused by stitching, and to predict the in-plane effective tensile strength of the stitched composite laminates. The distortion of in-plane fibers is considered to be the main cause that affects the in-plane mechanical properties. A fiber distortion model is proposed to characterize the fiber misalignment and the fiber content concentration due to stitching. The undistorted region, the fiber distortion region, the resin-rich pocket and the through-thickness reinforcement section are taken into account. The fiber misalignment and inhomogeneous fiber content due to stitching have been formulated by introducing two parameters, the distortion width and maximum misalignment. It has been found that the ply stress concentration in stitched laminates is influenced by the two concurrent factors, the stitch hole and inhomogeneous fiber content. The stitch hole brings about the stress concentration whereas the higher fiber content at the local region induced by stitching restrains the local deformation of the composite. The model is used to predict the tensile strength of the [0/45/0/-45/90/45/0/-45]2s T300/QY9512 composite laminate stitched by Kevlar 29 yarn with different stitching configurations, showing an acceptable agreement with experimental data.

  1. Micromechanics, fracture mechanics and gas permeability of composite laminates for cryogenic storage systems

    Science.gov (United States)

    Choi, Sukjoo

    A micromechanics method is developed to investigate microcrack propagation in a liquid hydrogen composite tank at cryogenic temperature. The unit cell is modeled using square and hexagonal shapes depends on fiber and matrix layout from microscopic images of composite laminates. Periodic boundary conditions are applied to the unit cell. The temperature dependent properties are taken into account in the analysis. The laminate properties estimated by the micromechanics method are compared with empirical solutions using constituent properties. The micro stresses in the fiber and matrix phases based on boundary conditions in laminate level are calculated to predict the formation of microcracks in the matrix. The method is applied to an actual liquid hydrogen storage system. The analysis predicts micro stresses in the matrix phase are large enough to cause microcracks in the composite. Stress singularity of a transverse crack normal to a ply-interface is investigated to predict the fracture behavior at cryogenic conditions using analytical and finite element analysis. When a transverse crack touches a ply-interface of a composite layer with same fiber orientation, the stress singularity is equal to ½. When the transverse crack propagates to a stiffer layer normal to a ply-direction, the singularity becomes less than ½ and vice versa. Finite element analysis is performed to evaluate fracture toughness of a laminated beam subjected to the fracture load measured by the fracture experiment at room and cryogenic temperatures. As results, the fracture load at cryogenic temperature is significantly lower than that at room temperature. However, when thermal stresses are taken into consideration, for both cases of room and cryogenic temperatures, the variation of fracture toughness becomes insignificant. The result indicates fracture toughness is a characteristic property which is independent to temperature changes. The experimental analysis is performed to investigate the

  2. Fabrication and characterization of laminated Ti-(TiB+La2O3/Ti composite

    Directory of Open Access Journals (Sweden)

    Yuanfei Han

    2015-10-01

    Full Text Available The incorporation of ceramic particulate reinforcements into titanium alloys can improve the specific strength and specific stiffness, while inevitably reduce the plasticity and ductility. In this study, in situ synthesized multilayer Ti-(TiB+La2O3/Ti composite was designed by learning from the microstructure of nature biological materials with excellent mechanical properties. The Ti-(TiB+La2O3/Ti composite with unique characteristic of laminated structure was prepared by combined powder metallurgy and hot rolling. The method has the synthesize advantages with in-situ reaction of Ti and LaB6 at high temperature and controllability of reinforcements size and constituent phases in composites. The result shows that the pores in the as sintered laminated structure composite completely disappeared after hot rolling at 1050 °C. The agglomerated reinforcement particles were well dispersed and distributed uniformly along the rolling direction. The thickness of pure Ti layer and (TiB+La2O3/Ti composite layer decreased from 1 mm to about 200 μm. Meanwhile, the grains size was refined obviously after rolling deformation. The room temperature tensile test indicates that the elongation of the laminated Ti-(TiB+La2O3/Ti composite improved from 13% to 17% in comparison with the uniform (TiB+La2O3/Ti composite, while the tensile strength had little change. It provides theoretical and experimental basis for fabricating the novel high performance laminated Ti-(TiB+La2O3/Ti composites.

  3. FEM Simulation of Bending Formability for Laminate Steel/Resin/Steel Lightweight Composite Sheet

    Institute of Scientific and Technical Information of China (English)

    Guancheng Ll; Yonglin KANG

    2003-01-01

    The ANSYS simulation software was used to analyze the bending formability of laminate steel/resin/steel lightweight composite sheet. The skin steel at external side produces relative slipping-off change during the bending due to its composite structure. The internal stress strain states, materials effect tools parameters and intermediate layer resin of lightweight sheet on slipping-off change were analyzed. The spring back and shear stress state after bending have also been discussed.

  4. Evaluating Volume Fractions of the Elements for Composite Laminates by Using Dielectric Properties

    Institute of Scientific and Technical Information of China (English)

    周胜; 储才元; 严灏景

    2001-01-01

    A series and parallel model for investigating the capacity of composite laminates and the relationship between the dielectric properties of the composites and its constituents are presented. Volume fractions of the constituents are considered in this study. The expression of the complex dielectric constants for evaluating volume fractions under discrete frequencies is established and the general solutions for the resultant linear simultaneous equations for system are also exploited.The results show that the high accuracy of proposed method is obtained.

  5. Thermal Stress Analysis of Laminated Composite Plates using Shear Flexible Element

    Directory of Open Access Journals (Sweden)

    M. Ganapathi

    1996-01-01

    Full Text Available Using degree Centigrade shear flexible QUAD-9 plate element, stresses and deflections in composite laminated plates due to thermal loads analysed. A formulation based on first order shear deformation theory has been employed for the analysis. The effects of various parameters, such as ply-angle, number of layers, thickness and aspect ratios on stresses and deflections are brought out. The present formulation is being extended for studying composite shell structures.

  6. Effect of Stacking Layup on Spring-back Deformation of Symmetrical Flat Laminate Composites Manufactured through Autoclave Processing

    Science.gov (United States)

    Nasir, M. N. M.; Seman, M. A.; Mezeix, L.; Aminanda, Y.; Rivai, A.; Ali, K. M.

    2017-03-01

    The residual stresses that develop within fibre-reinforced laminate composites during autoclave processing lead to dimensional warpage known as spring-back deformation. A number of experiments have been conducted on flat laminate composites with unidirectional fibre orientation to examine the effects of both the intrinsic and extrinsic parameters on the warpage. This paper extends the study on to the symmetrical layup effect on spring-back for flat laminate composites. Plies stacked at various symmetrical sequences were fabricated to observe the severity of the resulting warpage. Essentially, the experimental results demonstrated that the symmetrical layups reduce the laminate stiffness in its principal direction compared to the unidirectional laminate thus, raising the spring-back warpage with the exception of the [45/-45]S layup due to its quasi-isotropic property.

  7. Non-destructive evaluation of laminated composite plates using dielectrometry sensors

    Science.gov (United States)

    Nassr, Amr A.; El-Dakhakhni, Wael W.

    2009-05-01

    The use of composite materials in marine, aerospace and automotive applications is increasing; however, several kinds of damages of composite materials may influence its durability and future applications. In this paper, a methodology was presented for damage detection of laminated composite plates using dielectrometry sensors. The presence of damage in the laminated composite plate leads to changes in its dielectric characteristics, causing variation in the measured capacitance by the sensors. An analytical model was used to analyse the influence of different sensor parameters on the output signals and to optimize sensor design. Two-dimensional finite element (FE) simulations were performed to assess the validity of the analytical results and to evaluate other sensor design-related parameters. To experimentally verify the model, the dielectric permittivity of the composite plate was measured. In addition, a glass fibre reinforced polymer (GFRP) laminated plate containing pre-fabricated slots through its thickness to simulate delamination and water intrusion defects was inspected in a laboratory setting. Excellent agreements were found between the experimental capacitance response signals and those predicated from the FE simulations. This cost-effective technique can be used for rapid damage screening, regular scheduled inspection, or as a permanent sensor network within the composite system.

  8. Characterization of Degradation Progressive in Composite Laminates Subjected to Thermal Fatigue and Moisture Diffusion by Lamb Waves

    Directory of Open Access Journals (Sweden)

    Weibin Li

    2016-02-01

    Full Text Available Laminate composites which are widely used in the aeronautical industry, are usually subjected to frequency variation of environmental temperature and excessive humidity in the in-service environment. The thermal fatigue and moisture absorption in composites may induce material degradation. There is a demand to investigate the coupling damages mechanism and characterize the degradation evolution of composite laminates for the particular application. In this paper, the degradation evolution in unidirectional carbon/epoxy composite laminates subjected to thermal fatigue and moisture absorption is characterized by Lamb waves. The decrease rate of Lamb wave velocity is used to track the degradation evolution in the specimens. The results show that there are two stages for the progressive degradation of composites under the coupling effect of thermal cyclic loading and moisture diffusion. The present work provides an alternative to monitoring the degradation evolution of in-service aircraft composite Laminates.

  9. Characterization of Degradation Progressive in Composite Laminates Subjected to Thermal Fatigue and Moisture Diffusion by Lamb Waves.

    Science.gov (United States)

    Li, Weibin; Xu, Chunguang; Cho, Younho

    2016-01-01

    Laminate composites which are widely used in the aeronautical industry, are usually subjected to frequency variation of environmental temperature and excessive humidity in the in-service environment. The thermal fatigue and moisture absorption in composites may induce material degradation. There is a demand to investigate the coupling damages mechanism and characterize the degradation evolution of composite laminates for the particular application. In this paper, the degradation evolution in unidirectional carbon/epoxy composite laminates subjected to thermal fatigue and moisture absorption is characterized by Lamb waves. The decrease rate of Lamb wave velocity is used to track the degradation evolution in the specimens. The results show that there are two stages for the progressive degradation of composites under the coupling effect of thermal cyclic loading and moisture diffusion. The present work provides an alternative to monitoring the degradation evolution of in-service aircraft composite Laminates.

  10. Weak bond detection in composites using highly nonlinear solitary waves

    Science.gov (United States)

    Singhal, Taru; Kim, Eunho; Kim, Tae-Yeon; Yang, Jinkyu

    2017-05-01

    We experimentally investigate a diagnostic technique for identifying a weak bond in composites using highly nonlinear solitary waves (HNSWs). We set up a one-dimensional chain of granular crystals, consisting of spherical particles with nonlinear interactions, to generate HNSWs. These solitary wave packets are transmitted into an inspection area of composites by making a direct contact with the chain. We demonstrate that a strong type of solitary waves injected to the weak bond area can break the weak bond of laminates, thereby causing delamination. Then, to identify the creation of the delamination, we transmit a weak type of solitary waves by employing the same apparatus, and measure the solitary waves reflected from the specimens. By analyzing these reflected solitary waves, we differentiate the weak bond samples with the pristine bond ones in an efficient and fast manner. The diagnostic results based on the proposed method are compared with the strength and energy release rate at bond interfaces, which are measured via standard testing methods such as three point bending and end notched flexure tests. This study shows the potential of solitary wave-based detection of weak bonds for hot spot monitoring of composite-based structures.

  11. Clinical longevity of ceramic laminate veneers bonded to teeth with and without existing composite restorations up to 40 months

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Kalk, Warner; Ozcan, Mutlu

    2013-01-01

    This study evaluated the survival rate of ceramic laminate veneers bonded to teeth with and without existing composite restorations (ECR). Twenty patients (mean age: 49.7 years) received 92 feldspathic ceramic laminate veneers (Shofu Vintage AL) on the maxillary teeth (intact teeth: n = 26; teeth wi

  12. Robust buckling optimization of laminated composite structures using discrete material optimization considering “worst” shape imperfections

    DEFF Research Database (Denmark)

    Henrichsen, Søren Randrup; Lindgaard, Esben; Lund, Erik

    2015-01-01

    Robust buckling optimal design of laminated composite structures is conducted in this work. Optimal designs are obtained by considering geometric imperfections in the optimization procedure. Discrete Material Optimization is applied to obtain optimal laminate designs. The optimal geometric...... example. The imperfection sensitivity of the optimized structure decreases during the recurrence optimization for both examples, hence robust buckling optimal structures are designed....

  13. A Digital Algorithm for Composite Laminate Analysis - FORTRAN. Revision

    Science.gov (United States)

    1983-10-01

    Introduction to Composite Materials ,’! by...TAKEN FROM ’ INTRODUCTION TO COMPOSITE MATERIALS ’ BY S.W. TSAI AND H.T. HAHN. 2 strength prediction of hygrothermal loads are not included. However...1. S. W. Tsai and H. T. Hahn, Introduction to Composite Materials , Technomic Publishing Co., Westport, CT 06880, July 1980. 2. S. W. Tsai and R.

  14. Guided Wave Propagation Study on Laminated Composites by Frequency-Wavenumber Technique

    Science.gov (United States)

    Tian, Zhenhua; Yu, Lingyu; Leckey, Cara A. C.

    2014-01-01

    Toward the goal of delamination detection and quantification in laminated composites, this paper examines guided wave propagation and wave interaction with delamination damage in laminated carbon fiber reinforced polymer (CFRP) composites using frequency-wavenumber (f-kappa) analysis. Three-dimensional elastodynamic finite integration technique (EFIT) is used to acquire simulated time-space wavefields for a CFRP composite. The time-space wavefields show trapped waves in the delamination region. To unveil the wave propagation physics, the time-space wavefields are further analyzed by using two-dimensional (2D) Fourier transforms (FT). In the analysis results, new f-k components are observed when the incident guided waves interact with the delamination damage. These new f-kappa components in the simulations are experimentally verified through data obtained from scanning laser Doppler vibrometer (SLDV) tests. By filtering the new f-kappa components, delamination damage is detected and quantified.

  15. Strength and fatigue life evaluation of composite laminate with embedded sensors

    Science.gov (United States)

    Rathod, Vivek T.; Hiremath, S. R.; Roy Mahapatra, D.

    2014-04-01

    Prognosis regarding durability of composite structures using various Structural Health Monitoring (SHM) techniques is an important and challenging topic of research. Ultrasonic SHM systems with embedded transducers have potential application here due to their instant monitoring capability, compact packaging potential toward unobtrusiveness and noninvasiveness as compared to non-contact ultrasonic and eddy current techniques which require disassembly of the structure. However, embedded sensors pose a risk to the structure by acting as a flaw thereby reducing life. The present paper focuses on the determination of strength and fatigue life of the composite laminate with embedded film sensors like CNT nanocomposite, PVDF thin films and piezoceramic films. First, the techniques of embedding these sensors in composite laminates is described followed by the determination of static strength and fatigue life at coupon level testing in Universal Testing Machine (UTM). Failure mechanisms of the composite laminate with embedded sensors are studied for static and dynamic loading cases. The coupons are monitored for loading and failure using the embedded sensors. A comparison of the performance of these three types of embedded sensors is made to study their suitability in various applications. These three types of embedded sensors cover a wide variety of applications, and prove to be viable in embedded sensor based SHM of composite structures.

  16. Assessment of various failure theories for weight and cost optimized laminated composites using genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, T. [Indian Institute of Technology Kanpur. Dept. of Aerospace Engineering, UP (India); Gupta, R. [Infotech Enterprises Ltd., Hyderabad (India)

    2012-07-01

    In this work, minimum weight-cost design for laminated composites is presented. A genetic algorithm has been developed for the optimization process. Maximum-Stress, Tsai-Wu and Tsai-Hill failure criteria have been used along with buckling analysis parameter for the margin of safety calculations. The design variables include three materials; namely Carbon-Epoxy, Glass-Epoxy, Kevlar-Epoxy; number of plies; ply orientation angles, varying from -75 deg. to 90 deg. in the intervals of 15 deg. and ply thicknesses which depend on the material in use. The total cost is a sum of material cost and layup cost. Layup cost is a function of the ply angle. Validation studies for solution convergence and weight-cost inverse proportionality are carried out. One set of results for shear loading are also validated from literature for a particular case. A Pareto-Optimal solution set is demonstrated for biaxial loading conditions. It is then extended to applied moments. It is found that global optimum for a given loading condition is a function of the failure criteria for shear loading, with Maximum Stress criteria giving the lightest-cheapest and Tsai-Wu criteria giving the heaviest-costliest optimized laminates. Optimized weight results are plotted from the three criteria to do a comparative study. This work gives a global optimized laminated composite and also a set of other local optimum laminates for a given set of loading conditions. The current algorithm also provides with adequate data to supplement the use of different failure criteria for varying loadings. This work can find use in the industry and/or academia considering the increased use of laminated composites in modern wind blades. (Author)

  17. Effective ac response in weakly nonlinear composites

    Energy Technology Data Exchange (ETDEWEB)

    Wei Enbo [Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071 (China); Yang Zidong [College of Power Engineering, University of Shanghai Science and Technology, Shanghai 200093 (China); Gu Guoqing [Information College of Science and Technology, East China Normal University, Shanghai 200062 (China)

    2004-01-07

    The perturbation method is developed to deal with the problem of determining the effective nonlinear conductivity of Kerr-like nonlinear media under an external ac electric field. As an example, we have considered the cylindrical inclusion embedded in a host under the sinusoidal external field E{sub 1} sin (<{omega}t) + E{sub 3} sin (3<{omega}t) with frequencies{omega} and 3{omega}. The potentials of composites at higher harmonics are derived in both local inclusion particle and host regions. The effective responses of bulk nonlinear composites at basic frequency and harmonics are given for cylindrical composites in the dilute limit. Moreover, the relationships between the nonlinear effective responses at the basic frequency and the third harmonics are derived.

  18. DETERMINATION OF EFFECTIVE PROPERTIES OF FIBER-REINFORCED COMPOSITE LAMINATES

    Directory of Open Access Journals (Sweden)

    Andrzej Skrzat

    2014-06-01

    Full Text Available The determination of effective mechanical properties of multi-layer composite is presented in this paper. Computations based on finite element method predicting properties of inhomogeneous materials require solving huge tasks. More effective is Mori-Tanaka approach, typical for micromechanics problems. For regularly distributed fibers closed-forms for effective composite material properties are possible to derive. The results of homogenization are used in strength analysis of the composite pressure vessel.

  19. Fracture morphology of carbon fiber reinforced plastic composite laminates

    OpenAIRE

    Vinod Srinivasa; Vinay Shivakumar; Vinay Nayaka; Sunil Jagadeeshaiaih; Murali Seethram; Raghavendra Shenoy; Abdelhakim Nafidi

    2010-01-01

    Carbon fiber reinforced plastic (CFRP) composites have been extensively used in fabrication of primary structures for aerospace, automobile and other engineering applications. With continuous and widespread use of these composites in several advanced technology, the frequency of failures is likely to increase. Therefore, to establish the reasons for failures, the fracture modes should be understood thoroughly and unambiguously. In this paper, CFRP composite have been tested in tension, compre...

  20. Improvements to the Processing and Characterization of Needled Composite Laminates

    Science.gov (United States)

    2014-01-01

    Tensile Properties of Polymer Matrix Composite Materials,” ASTM International, West Conshohocken, PA. 22. ASTM D6641M-09. 2009. “Standard Test Method...for Compressive Properties of Polymer Matrix Composite Materials Using a Combined Loading Compression (CLC) Test Fixture,” ASTM International, West

  1. Characterization and modeling of performance of Polymer Composites Reinforced with Highly Non-Linear Cellulosic Fibers

    Science.gov (United States)

    Rozite, L.; Joffe, R.; Varna, J.; Nyström, B.

    2012-02-01

    The behaviour of highly non-linear cellulosic fibers and their composite is characterized. Micro-mechanisms occurring in these materials are identified. Mechanical properties of regenerated cellulose fibers and composites are obtained using simple tensile test. Material visco-plastic and visco-elastic properties are analyzed using creep tests. Two bio-based resins are used in this study - Tribest and EpoBioX. The glass and flax fiber composites are used as reference materials to compare with Cordenka fiber laminates.

  2. Fracture morphology of carbon fiber reinforced plastic composite laminates

    Directory of Open Access Journals (Sweden)

    Vinod Srinivasa

    2010-09-01

    Full Text Available Carbon fiber reinforced plastic (CFRP composites have been extensively used in fabrication of primary structures for aerospace, automobile and other engineering applications. With continuous and widespread use of these composites in several advanced technology, the frequency of failures is likely to increase. Therefore, to establish the reasons for failures, the fracture modes should be understood thoroughly and unambiguously. In this paper, CFRP composite have been tested in tension, compression and flexural loadings; and microscopic study with the aid of Scanning Electron Microscope (SEM has been performed on failed (fractured composite surfaces to identify the principle features of failure. Efforts have been made in correlating the fracture surface characteristics to the failure mode. The micro-mechanics analysis of failure serves as a useful guide in selecting constituent materials and designing composites from the failure behavior point of view. Also, the local failure initiation results obtained here has been reliably extended to global failure prediction.

  3. Ballistic Impact Response of Woven Hybrid Coir/Kevlar Laminated Composites

    Directory of Open Access Journals (Sweden)

    Azrin Hani A.R

    2016-01-01

    Full Text Available The effects of different laminated hybrid composites stacking configuration subjected to ballistic impact were investigated. The hybrid composites consist of woven coir (C and woven Kevlar (K layers laminated together. The samples of woven coir were prepared using handloom device. The composites were produced by stacking the laminated woven coir and Kevlar alternately with the presence of the binder. The samples were tested under ballistic impact with different stacking configuration. The results obtained had successfully achieved the National Institute of Justice (NIJ standard level IIA with energy absorption of 435.6 kJ and 412.2 kJ under the projectile speed of between 330 m/s and 321 m/s respectively. Samples that having Kevlar layer at the front face and woven coir layer as back face achieved partial penetration during projectile impact. This orientation is proven to have good impact energy absorption and able to stop projectile at the second panel of the composites.

  4. Mechanical Response of Stitched T300 Mat/Urethane 420 IMR Composite Laminates: Property/Orientation Dependence and Damage Evolution

    Energy Technology Data Exchange (ETDEWEB)

    Deng, S.; Weitsman, Y.J.

    2000-03-01

    This report presents experimental and analytical results of investigations on the mechanical response of stitched T300 mat/urethane 420 IMR composite laminates with three different lay-up configurations. Tensile tests and short-term creep and recovery tests were conducted on the laminate coupons at various orientations. The X-ray photographic technique was adopted to detect the internal damage due to external loading history. The tensile data of laminates with antisymmetric and symmetric lay-ups indicated that lay- up sequences of cross-ply laminates do not have much influence on their tensile properties. However, misalignments within the stitch-bonded plies disturb the symmetry of intended quasi-isotropic laminates and thereby cause the mechanical properties to exhibit a certain amount of angular dependence. Classic lamination theory was found to be able to provide a very good prediction of tensile properties for the stitched laminates within linear range. Creep and recovery response of laminate coupons is greatly dependent on loading angles and load levels. The internal damage of laminate coupons is also directly related to loading angles and load levels as well as loading history.

  5. Low-velocity Impact Damage Analysis of Composite Laminates Using Self-adapting Delamination Element Method

    Institute of Scientific and Technical Information of China (English)

    Wang Lipeng; Yan Ying; Wu Dafang; Wu Hao

    2008-01-01

    On the basis of a 2D 4-node Mindlin shell element method, a novel self-adapting delamination finite element method is presented,which is developed to model the delamination damage of composite laminates. In the method, the sublaminate elements are generated automatically when the delamination damage occurs or extends. Thus, the complex process and state of delamination damage can be simulated practically with high efficiency for both analysis and modeling. Based on the self-adapting delamination method, linear dynamic finite element damage analysis is performed to simulate the low-velocity impact damage process of three types of mixed woven composite laminates. Taking the frictional force among sublaminations during delaminating and the transverse normal stress into account,the analytical results ate consistent with those of the experimental data.

  6. Characterization of Delaminations and Transverse Matrix Cracks in Composite Laminates Using Multiple-Angle Ultrasonic Inspection

    Science.gov (United States)

    Johnston, Patrick H.; Appleget, Chelsea D.; Odarczenko, Michael T.

    2012-01-01

    Delaminations and transverse matrix cracks often appear concurrently in composite laminates. Normal-incidence ultrasound is excellent at detecting delaminations, but is not optimum for matrix cracks. Non-normal incidence, or polar backscattering, has been shown to optimally detect matrix cracks oriented perpendicular to the ultrasonic plane of incidence. In this work, a series of six composite laminates containing slots were loaded in tension to achieve various levels of delamination and ply cracking. Ultrasonic backscattering was measured over a range of incident polar and azimuthal angles, in order to characterize the relative degree of damage of the two types. Sweptpolar- angle measurements were taken with a curved phased array, as a step toward an array-based approach to simultaneous measurement of combined flaws.

  7. Stress Distribution of CF/EP Laminated Composites under Supercritical Conditions

    Directory of Open Access Journals (Sweden)

    Haihong Huang

    2015-01-01

    Full Text Available Enormous amounts of wastes have been produced due to extensive use of carbon fiber/epoxy resin (CF/EP composites. The fact that the supercritical fluid can be used to recycle these composites efficiently has attracted widespread concerns. A three-dimensional model of CF/EP laminates considering the interfacial layers was established. The internal stress distribution of laminates was simulated based on a heat transfer model; and the change of shear stress with supercritical temperature and pressure was investigated. The results show that the shear stress concentration was located in the interfacial layers; the maximum shear stress can be expressed by a curve of convex parabola to the temperature; and the most serious damage occurred in interfacial layers when temperature approached the glass-transition temperature of resin.

  8. Shear Strength of Single Lap Joint Aluminium-Thermoplastic Natural Rubber (Al-TPNR) Laminated Composite

    Science.gov (United States)

    Muzakkar, M. Z.; Ahmad, S.; Yarmo, M. A.; Jalar, A.; Bijarimi, M.

    2013-04-01

    In this work, we studied the effect of surface treatment on the aluminium surface and a coupling agent to improve adhesion between aluminium with organic polymer. Thermoplastic natural rubber (TPNR) matrix was prepared by melt blending of natural rubber (NR), liquid natural rubber (LNR) compatibilizer, linear low density polyethylene (LLDPE) and polyethylene grafted maleic anhydride (PE-g-MAH). The PEgMAH concentration used was varied from 0% - 25%. In addition, the aluminium surface was pre-treated with 3-glycidoxy propyl trimethoxy silane (3-GPS) to enhance the mechanical properties of laminated composite. It was found that the shear strength of single lap joint Al-TPNR laminated composite showing an increasing trend as a function of PE-g-MAH contents for the 3-GPS surface treated aluminium. Moreover, the scanning electron microscope (SEM) revealed that the strength improvement was associated with the chemical state of the compound involved.

  9. Investigation of the dynamic effects of partial sensor debonding in smart composite laminates

    Science.gov (United States)

    Khan, Asif; Kim, Heung Soo

    2016-04-01

    Dynamic characteristics of smart composite laminate with partially debonded piezoelectric sensor are investigated. Improved layerwise theory with Heaviside's unit step function is used to model the discontinuous displacement field with jumps owing to the in-plane slipping and out-of-plane opening at the debonded interface. Higher order electric potential field is employed to describe the potential variation through the thickness of piezoelectric patches. Finite element method and extended Hamilton's principle are used to derive the governing equation of motion. The governing equation is solved in time domain using Newmark time integration algorithm. The developed model is numerically implemented on a laminated composite plate with surface bonded piezoelectric actuator and partially debonded sensor. The sensing capability is evaluated in the presence of partial inner and edge debonding in the piezoelectric sensor.

  10. Characterizing formation of interfacial domain wall and exchange coupling strength in laminated exchange coupled composites

    Science.gov (United States)

    Hou, H.-C.; Kirby, B. J.; Gao, K. Z.; Lai, C.-H.

    2013-04-01

    We have studied the N-dependent switching behavior of composite magnets, comprised of a hard CoPtCr-SiO2 (CPCS) film and a laminated soft [Pt/CPCS]N multilayer. First order reversal curve magnetometry provides evidence of interfacial domain wall (iDW) assisted reversal for N ≥ 5. The magnetic depth profiles determined from polarized neutron reflectometry (PNR) explicitly demonstrate that the composite magnets are more rigidly coupled for N = 3 than for N = 7, and suggest that for N = 7 reversal occurs via formation of iDW. By fitting the PNR profile into the energy surface calculations, we can further deduce the vertical coupling strength in the laminated soft layer.

  11. Prediction of Final Velocity of Aramid Fabric-Resin Composite Laminates Subjected to Ballistic Impact

    Institute of Scientific and Technical Information of China (English)

    熊杰; 萧庆亮; 刘冠峰; 顾伯洪; 王善元

    2003-01-01

    The strain rate effects of aramid fiber material,quasi-static and ballistic impact perforation of composite laminates made of aramid fabric and phenolic resin/PVB are investigated respectively by means of MTS, split Hopkinson tension bars and ballistic impact apparatus. The tensile impact experiments on aramid fiber material are performed in strain rate range from 0.01/ s to 1 000/ s. Experinental results show that the mechanical properties of aramid fiber material are insensitive to strain rate in the range from 0. 01/s to 1 000/s. An energy model to predict final velocity of composite laminates subjected to ballistic impact is proposed on the basis of experimental data of quasi-static perforation through the targets. The predicted final velocities show good agreement with the experimental final velocity.

  12. Development of ferrous laminated composites with unique microstructures by control of carbon diffusion

    Science.gov (United States)

    Kum, D. W.; Oyama, T.; Ruano, O. A.; Sherby, O. D.

    1986-09-01

    A novel method is described for preparing ferrous laminated composites, containing ultrahigh carbon steel as one of the components, which results in hard and soft layers bounded by sharp and discrete interfaces. The method is based on increasing the activity of carbon in iron by silicon addition; in this manner, the carbon is made to segregate into specific layers by heat treatment at low temperatures (˜770 °C). The results are ferrous laminated composites with discrete and sharp interfaces that consist of hard layers containing spherical carbide particles embedded in a matrix of ultrafine martensite or ferrite adjoining soft layers of a coarse grained iron alloy. In addition, the high activity of carbon is shown to result in total depletion of carbon in a silicon containing UHC steel ribbon bonded to mild steel.

  13. Damage states in laminated composite three-point bend specimens: An experimental-analytical correlation study

    Science.gov (United States)

    Starbuck, J. Michael; Guerdal, Zafer; Pindera, Marek-Jerzy; Poe, Clarence C.

    1990-01-01

    Damage states in laminated composites were studied by considering the model problem of a laminated beam subjected to three-point bending. A combination of experimental and theoretical research techniques was used to correlate the experimental results with the analytical stress distributions. The analytical solution procedure was based on the stress formulation approach of the mathematical theory of elasticity. The solution procedure is capable of calculating the ply-level stresses and beam displacements for any laminated beam of finite length using the generalized plane deformation or plane stress state assumption. Prior to conducting the experimental phase, the results from preliminary analyses were examined. Significant effects in the ply-level stress distributions were seen depending on the fiber orientation, aspect ratio, and whether or not a grouped or interspersed stacking sequence was used. The experimental investigation was conducted to determine the different damage modes in laminated three-point bend specimens. The test matrix consisted of three-point bend specimens of 0 deg unidirectional, cross-ply, and quasi-isotropic stacking sequences. The dependence of the damage initiation loads and ultimate failure loads were studied, and their relation to damage susceptibility and damage tolerance of the mean configuration was discussed. Damage modes were identified by visual inspection of the damaged specimens using an optical microscope. The four fundamental damage mechanisms identified were delaminations, matrix cracking, fiber breakage, and crushing. The correlation study between the experimental results and the analytical results were performed for the midspan deflection, indentation, damage modes, and damage susceptibility.

  14. An efficient computational strategy for composite laminates assemblies including variability

    National Research Council Canada - National Science Library

    Roulet, V; Boucard, P.-A; Champaney, L

    2013-01-01

    The aim of this work is to present an efficient numerical strategy for studying the influence of the material parameters on problems involving 3D assemblies of composite parts with contact and friction...

  15. Nonlinear analysis and vibration suppression control for a rigid-flexible coupling satellite antenna system composed of laminated shell reflector

    Science.gov (United States)

    You, Bin Di; Wen, Jian Min; Zhao, Yang

    2014-03-01

    In this paper, a nonlinear dynamic modeling method for a rigid-flexible coupling satellite antenna system composed of laminated shell reflector is proposed undergoing a large overall motion. For the study of the characteristics of the reflector using laminated shell structure, the displacement field description of a point in a 3-noded shell element is acquired in conjunction with the length stretch, lateral bending and torsional deformation. Hence, a nonlinear dynamic model of the satellite antenna system is deduced based on Lagrange's equations. The complete expressions of nonlinear terms of elastic deformation and coupling terms between rigid motion and large deflection are considered in the dynamic equations, and the dynamic behavior of the rigid-flexible coupling system is analyzed using linear model and nonlinear model, respectively. In order to eliminate the system vibration, the PD with vibration force feedback control strategy is used to achieve its desired angles and velocity in a much shorter duration, and can further accomplish reduction of residual vibration. Then, the asymptotic stability of the system is proved based on the Lyapunov method. Through numerical computation, the results show that the linear model cannot capture the motion-induced coupling terms and geometric nonlinearity variations. However, the nonlinear model is suitable for dealing with large deformation rigid-flexible problem undergoing large overall motions. Hence, the satellite antenna pointing accuracy would be predicted based on the nonlinear model. Furthermore, the results also show that the proposed control strategy can suppress system vibration quickly. The above conclusions would have important academic significance and engineering value.

  16. DMTO – a method for Discrete Material and Thickness Optimization of laminated composite structures

    DEFF Research Database (Denmark)

    Sørensen, Søren Nørgaard; Sørensen, Rene; Lund, Erik

    2014-01-01

    are optimized simultaneously through interpolation functions with penalization. Numerical results for several parameterizations of a finite element model of a generic main spar from a wind turbine blade are presented. The different parameterizations represent different levels of complexity with respect......This paper presents a gradient based topology optimization method for Discrete Material and Thickness Optimization of laminated composite structures, labelled the DMTOmethod. The capabilities of the proposed method are demonstrated on mass minimization, subject to constraints on the structural...

  17. Free Vibration Analysis of a Cross-Ply Laminated Composite Beam on Pasternak Foundation

    OpenAIRE

    R. A. Jafari-Talookolaei; Ahmadian, M. T.

    2007-01-01

    In this study, free vibration analysis of a cross-ply laminated composite beam (LCB) on Pasternak foundation was investigated. Natural frequencies of beam on Pasternak foundation are computed using finite element method (FEM) on the basis of Timoshenko beam theory. Effect of both shear deformation and rotary inertia are implemented in the modeling of stiffness and mass matrices. The model was designed in such a way that it can be used for single-stepped cross-section, stepped foundation and m...

  18. Guided Wave and Damage Detection in Composite Laminates Using Different Fiber Optic Sensors

    OpenAIRE

    Fucai Li; Hideaki Murayama; Kazuro Kageyama; Takehiro Shirai

    2009-01-01

    Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber r...

  19. Thickness optimization of laminated composites using the discrete material optimization method

    DEFF Research Database (Denmark)

    Sørensen, Søren Nørgaard; Sørensen, Rene; Lund, Erik

    2012-01-01

    This work concerns a novel large scale multi-material topology optimization method for simultaneous determination of the optimum variable integer thickness and fiber orientation throughout laminated composites with fixed outer geometries while adhering to certain manufacturing constraints....... The conceptual combinatorial/integer problem is relaxed to a continuous problem and solved on basis of the so-called Discrete Material Optimization method, explicitly including the manufacturing constraints as linear constraints....

  20. Numerical anlysis of the vacuum infusion process for laminated composites with different fiber orientations.

    OpenAIRE

    Hurtado, Francisco José; Sánchez Kaiser, Antonio; Viedma Robles, Antonio; Díaz, Sebastián

    2015-01-01

    The vacuum infusion (VI) is a process usually applied to manufacture large structures of composite materials, such as wind turbine blades. Present work analyzes the macroscopic resin ow through a laminate of fiberglass plies with different orientations, during the filling stage of the VI process to manufacture two different pieces. The pressure inside the mold, velocity vectors and the resin inlet mass flow are studied through a 3D numerical modeling under non-steady conditions vali...

  1. Lamination of microfibrous PLGA fabric by electrospinning a layer of collagen-hydroxyapatite composite nanofibers for bone tissue engineering

    OpenAIRE

    Kwon, Gi-Wan; Gupta, Kailash Chandra; Jung, Kyung-Hye; Kang, Inn-Kyu

    2017-01-01

    Background To mimic the muscle inspired cells adhesion through proteins secretion, the lamination of collagen?hydroxyapatite nanorod (nHA) composite nanofibers has been carried out successfully on polydopamine (PDA)-coated microfibrous polylactide-co-glycolide (PLGA) fabrics. The lamination of collagen-hydroxyapatite composite nanofibers on polydopamine-coated microfibrous PLGA fabrics was carried through electrospinning the solution of collagen containing L-glutamic acid-grafted hydroxyapati...

  2. Extended layerwise method for laminated composite plates with multiple delaminations and transverse cracks

    Science.gov (United States)

    Li, D. H.; Zhang, X.; Sze, K. Y.; Liu, Y.

    2016-10-01

    In this paper, the extended layerwise method (XLWM), which was developed for laminated composite beams with multiple delaminations and transverse cracks (Li et al. in Int J Numer Methods Eng 101:407-434, 2015), is extended to laminated composite plates. The strong and weak discontinuous functions along the thickness direction are adopted to simulate multiple delaminations and interlaminar interfaces, respectively, whilst transverse cracks are modeled by the extended finite element method (XFEM). The interaction integral method and maximum circumferential tensile criterion are used to calculate the stress intensity factor (SIF) and crack growth angle, respectively. The XLWM for laminated composite plates can accurately predicts the displacement and stress fields near the crack tips and delamination fronts. The thickness distribution of SIF and thus the crack growth angles in different layers can be obtained. These information cannot be predicted by using other existing shell elements enriched by XFEM. Several numerical examples are studied to demonstrate the capabilities of the XLWM in static response analyses, SIF calculations and crack growth predictions.

  3. Laser bendability of SUS430/C11000/SUS430 laminated composite and its constituent layers

    Science.gov (United States)

    Hossein Seyedkashi, S. M.; Gollo, Mohammad Hoseinpour; Biao, Jin; Moon, Young Hoon

    2016-05-01

    Laminated composites are of great interest in different industries while having the advantages of all base metals. In this research, the laser bending of a three-layered SUS430/C11000/SUS430 laminated composite is characterized both experimentally and numerically. This composite can be used in the microelectronics industry since it has the anti-corrosion and strength capability of stainless steel, and the electrical superiority of copper. The specimens are bent using a Ytterbium fiber laser irradiated on a straight path along the sheet width. The effects of bending parameters including the number of passes, scanning velocity, beam diameter, laser power and delay time between passes are examined for a three-layered laminated sheet, and compared with its constituent steel and copper layers. It is found that the thin copper mid-layer strongly affects the rate of bending per pass. Heat distribution and plastic strain along the thickness during the process are characterized by using the finite element method. The Cu mid-layer decreases the bending angle, but also postpones the onset of melting, and thus can be compensated by the application of higher laser powers. It is shown that the bending angle increases with an increase in laser power and delay time, and a decrease in laser velocity and beam diameter.

  4. Influence of the Geometric Parameters on the Mechanical Behaviour of Fabric Reinforced Composite Laminates

    Science.gov (United States)

    Axinte, Andrei; Taranu, Nicolae; Bejan, Liliana

    2016-10-01

    A polymer fabric reinforced composite is a high performance material, which combines strength of the fibres with the flexibility and ductility of the matrix. For a better drapeability, the tows of fibres are interleaved, resulting the woven fabric, used as reinforcement. The complex geometric shape of the fabric is of paramount importance in establishing the deformability of the textile reinforced composite laminates. In this paper, an approach based on Classical Lamination Theory ( CLT), combined with Finite Element Methods ( FEM), using Failure Analysis and Internal Load Redistribution, is utilised, in order to compare the behaviour of the material under specific loads. The main goal is to analyse the deformability of certain types of textile reinforced composite laminates, using carbon fibre satin as reinforcement and epoxy resin as matrix. This is accomplished by studying the variation of the in-plane strains, given the fluctuation of several geometric parameters, namely the width of the reinforcing tow, the gap between two consecutive tows, the angle of laminae in a multi-layered configuration and the tows fibre volume fraction.

  5. Adhesive Through-Reinforcement Improves the Fracture Toughness of a Laminated Birch Wood Composite

    Directory of Open Access Journals (Sweden)

    Wenchang He

    2017-01-01

    Full Text Available In this paper we test the hypothesis that adhesive through-reinforcement in combination with glass-fibre reinforcement of adhesive bond lines will significantly improve the fracture toughness of a laminated birch wood composite. We test this hypothesis using a model composite consisting of perforated veneer that allowed a polyurethane adhesive to penetrate and reinforce veneers within the composite. Model composite specimens were tested for mode I fracture properties, and scanning electron microscopy was used to examine the microstructure of fracture surfaces. Our results clearly show that through-reinforcement, and also reinforcing adhesive bond lines with glass-fibre, significantly improved fracture toughness of the birch wood composite. Our results also indicate that improvements in fracture toughness depended on the level of reinforcement. Improvements in fracture toughness were related to the ability of the reinforcement to arrest crack development during fracture testing and the fibre bridging effect of glass-fibre in adhesive bond lines. We conclude that through-reinforcement is an effective way of improving the fracture toughness of laminated wood composites, but further research is needed to develop practical ways of creating such reinforcement in composites that more closely resemble commercial products.

  6. Static Aeroelastic Optimization of Composite Wings with Variable Stiffness Laminates

    NARCIS (Netherlands)

    Dillinger, J.K.S.

    2014-01-01

    The application of composite material in load carrying structural components of an aircraft is rapidly gaining momentum. While part of the reason for this can certainly be attributed to an increasing confidence of designers in the new material as a result of growing experience, two other crucial poi

  7. Optimal Design of Variable Stiffness Composite Structures using Lamination Parameters

    NARCIS (Netherlands)

    IJsselmuiden, S.T.

    2011-01-01

    Fiber reinforced composite materials have gained widespread acceptance for a multitude of applications in the aerospace, automotive, maritime and wind-energy industries. Automated fiber placement technologies have developed rapidly over the past two decades, driven primarily by a need to reduce m

  8. Optimal Design of Variable Stiffness Composite Structures using Lamination Parameters

    NARCIS (Netherlands)

    IJsselmuiden, S.T.

    2011-01-01

    Fiber reinforced composite materials have gained widespread acceptance for a multitude of applications in the aerospace, automotive, maritime and wind-energy industries. Automated fiber placement technologies have developed rapidly over the past two decades, driven primarily by a need to reduce m

  9. Delamination and debonding failure of laminated composite T-joints

    NARCIS (Netherlands)

    Cui, H.

    2014-01-01

    Composites are increasingly being used in aerospace, automotive and other industries. The T-joint (also named stringer stiffened skin) is a typical connection, broadly used in thin-walled structures, such as the wing and fuselage of aircraft. This thesis presents the analysis of the delamination and

  10. Esthetic Rehabilitation of Anterior Teeth with Laminates Composite Veneers

    OpenAIRE

    Dino Re; Gabriele Augusti; Massimo Amato; Giancarlo Riva; Davide Augusti

    2014-01-01

    No- or minimal-preparation veneers associated with enamel preservation offer predictable results in esthetic dentistry; indirect additive anterior composite restorations represent a quick, minimally invasive, inexpensive, and repairable option for a smile enhancement treatment plan. Current laboratory techniques associated with a strict clinical protocol satisfy patients’ restorative and esthetic needs. The case report presented describes minimal invasive treatment of four upper incisors with...

  11. Free Edge Mixed Mode Delamination Analysis of Laminated Composites with Wrap-Around Configuration: A Finite Element Study

    Science.gov (United States)

    Choudhury, Pannalal; Das, Subhankar; Halder, Sudipta; Pandey, Krishna Murari

    2016-10-01

    Finite element analyses of laminated composites were done in the present study with respect to suppression of free edge delamination by an innovative technique. Wrap-around configuration was considered to determine its effectiveness over the wrapper-less laminated configuration on laminated composites. Nodal stresses were generated ahead of the crack tip through finite element analysis. This was used for determining interlaminar normal stress and inter laminar shear stress distributions at the critical interface. Later virtual crack closure technique was used to estimate the strain energy release rate components for several sizes of virtual crack extensions through a single finite element analysis. Computational analysis predicts Mode-I delamination as dominant mode of failure. This mode of delamination was significantly suppressed with wrap-around configuration on laminated composites.

  12. Development and characterization of ordered, highly oriented, composite laminates using supercritical carbon dioxide

    Science.gov (United States)

    Caskey, Terrence Colin

    This thesis describes the development and subsequent characterization of a series of oriented, highly ordered laminated composite materials. These laminated composite materials all possess order over varying length-scales from angstrom level molecular chain orientation to macro-scale order in woven fabrics. In each case, supercritical carbon dioxide (SC CO2) is used as a unique reaction medium and processing aid allowing for the development of structures not previously attainable with standard techniques. The goal of this research is two-fold, the first goal involves the proof of concept, exhibiting the ability to attain novel composite structures using unique SC CO2 chemistries and processes. The second goal of this research is aimed at developing a thorough understanding of how these unique structures and morphologies translate into an overall mechanical response for the material. This work will be divided into three distinct but interrelated projects. The first project involves the development of a unique SC CO2 assisted solvent welding technique. This technique is then applied towards the fabrication of a quasi-isotropic laminate comprised of a series of solvent-welded uniaxially-oriented linear low density polyethylene films (LLDPE). The geometry of this laminate is designed to exploit the improved strength and rigidity of uniaxially oriented LLDPE films while suppressing undesireable transverse properties. The second project to be addressed in this project involves the development of fiber-reinforced composites with unique nano-scale morphologies. The long-range order in these composites has profound effects on both the individual fiber properties as well as the overall composite properties. The final project of interest in this work involves the development of intercalated silicate nano-composites with high clay content. In order to achieve the desired morphologies it is necessary to create polymer/clay nano-composites with very high clay content

  13. Analysis of noncoplanar pressurized laminations in X2 steel pipes by non-linear finite element

    Energy Technology Data Exchange (ETDEWEB)

    Morales, Alfredo [Instituto Tecnologico de Puebla (Mexico). Dept. de Posgrado; Gonzalez, Jorge L.; Hallen, Jose M. [Instituto Politecnico Nacional (Mexico). Escuela Superior de Ingenieria Quimica e Industrias Extractivas (ESIQIE). Dept. de Ingenieria Metalurgica

    2005-07-01

    Hydrogen induced cracking is of great interest in the mechanical integrity assessment of sour gas pipelines. Multiple stepwise cracks with internal pressure called laminations are often observed in pipelines and their interaction and coalescence may significantly affect the residual strength of the pipes. In this work, the interacting fields of non coplanar pressurized laminations in the wall of a pipe under pressure are analyzed by non-lineal finite element, considering an isotropic hardening law and the real tensile properties of the X52 steel. The results are presented as the evolution of the stress fields in the interlaminar region as a function of the pressure inside the laminations. It is found that for two approaching stepwise laminations the critical pressure follows a hyperbolic type law, thus the effect of the lamination length is principal for greater lengths and for shorter lengths the effect is minimum. The critical pressure is defined as pressure inside the lamination that causes plastification of the interlaminar region. (author)

  14. Dispersion of guided waves in composite laminates and sandwich panels

    Science.gov (United States)

    Schaal, Christoph; Mal, Ajit

    2015-03-01

    In composite structures, damages are often invisible from the surface and can grow to reach a critical size, potentially causing catastrophic failure of the entire structure. Thus safe operation of these structures requires careful monitoring of the initiation and growth of such defects. Ultrasonic methods using guided waves offer a reliable and cost-effective method for structural health monitoring in advanced structures. Guided waves allow for long monitoring ranges and are very sensitive to defects within their propagation path. In this work, the relevant properties of guided Lamb waves for damage detection in composite structures are investigated. An efficient numerical approach is used to determine their dispersion characteristics, and these results are compared to those from laboratory experiments. The experiments are based on a pitch-catch method, in which a pair of movable transducers is placed on one surface of the structure to induce and detect guided Lamb waves. The specific cases considered include an aluminum plate and an aluminum honeycomb sandwich panel with woven composite face sheets. In addition, a disbond of the interface between one of the face sheets and the honeycomb core of the sandwich panel is also considered, and the dispersion characteristics of the two resultant waveguides are determined. Good agreement between numerical and experimental dispersion results is found, and suggestions on the applicability of the pitch-catch system for structural health monitoring are made.

  15. EXPERIMENTAL INVESTIGATIONS OF MODAL PARAMETERS OF LAMINATED COMPOSITES (GRAPHITE & KEVLAR USING FFT ANALYZER

    Directory of Open Access Journals (Sweden)

    K. MAHESH DUTT

    2012-06-01

    Full Text Available The laminated composite beams are basic structural components used in a variety of Fiber reinforced composites are finding engineering structures such as airplane wings, helicopter blades and turbine blades as well as many others in the aerospace, mechanical, and civil industries. An important element in the dynamic analysis of composite beams is the computation of their natural frequencies and mode shapes. This is important because composite beam structures often operate in complex environmental conditions and are frequentlyexposed to a variety of dynamic excitations. In this paper, a combined finite element and experimental approach is used to characterize the vibration behavior of composite laminates. Specimens are made using the hand-layup process. Graphite and Kevlar fibers are used as reinforcement in the form of bidirectional fabric and generalpurpose Epoxy resin as matrix for the composite material of beams. Experimental dynamic tests are carried out using specimens with different fiber orientations. From the results, the influence of fiber orientations on the flexural natural frequencies is investigated. Also, these experiments are used to validate the results obtained from the finite element software ANSYS.

  16. Investigation of actuator debonding effects on active control in smart composite laminates

    Directory of Open Access Journals (Sweden)

    Bin Huang

    2015-04-01

    Full Text Available This article presents a numerical study of active vibration control of smart composite laminates in the presence of actuator debonding failures. A comparison between the smart composite laminates with healthy actuator and various partially debonded actuator cases is performed to investigate the debonding effects on the vibration suppression. The improved layerwise theory with Heaviside’s unit step function is adopted to model the displacement field with actuator debonding failure. The higher order electric potential field is adopted to describe the potential variation through the thickness. The finite element method–based formulations are derived using the plate element, taking into consideration the electro-mechanical coupling effect. The reduced-order model is represented by the state-space form and further for the vibration suppression using a simple constant gain velocity feedback control strategy. For the purpose of demonstration, a 16-layer cross-ply substrate laminate ([0/90]4s is employed for the numerical study. The results show that the actuator debonding affects the closed-loop frequencies, active damping ratios, and efficiency of vibration suppression.

  17. Characterization and analysis of carbon fibre-reinforced polymer composite laminates with embedded circular vasculature.

    Science.gov (United States)

    Huang, C-Y; Trask, R S; Bond, I P

    2010-08-06

    A study of the influence of embedded circular hollow vascules on structural performance of a fibre-reinforced polymer (FRP) composite laminate is presented. Incorporating such vascules will lead to multi-functional composites by bestowing functions such as self-healing and active thermal management. However, the presence of off-axis vascules leads to localized disruption to the fibre architecture, i.e. resin-rich pockets, which are regarded as internal defects and may cause stress concentrations within the structure. Engineering approaches for creating these simple vascule geometries in conventional FRP laminates are proposed and demonstrated. This study includes development of a manufacturing method for forming vascules, microscopic characterization of their effect on the laminate, finite element (FE) analysis of crack initiation and failure under load, and validation of the FE results via mechanical testing observed using high-speed photography. The failure behaviour predicted by FE modelling is in good agreement with experimental results. The reduction in compressive strength owing to the embedding of circular vascules ranges from 13 to 70 per cent, which correlates with vascule dimension.

  18. Effect of laminate thickness on moisture diffusion of polymer matrix composites in artificial seawater ageing

    Science.gov (United States)

    Pal, Ratna; Narasimha Murthy, H. N.; Sreejith, M.; Vishnu Mahesh, K. R.; Krishna, M.; Sharma, S. C.

    2012-09-01

    The influence of laminate thickness of polymer matrix composites on moisture diffusion in seawater immersion, as well as the resulting mechanical property degradation for composites of glass/isopolyester (G/IPE), carbon/isopolyester (C/IPE), glass/vinylester (G/VE) and carbon/vinylester (C/VE), was investigated in this paper. Laminates 3 and 10mm in thickness, fabricated using the wet hand lay-up technique, were characterized for moisture absorption in artificial seawater medium, and their flexural strength and interlaminar shear strength (ILSS) degradations were studied. Moisture diffusion was observed to be anamolous to the Fick's law for both 3 and 10mm thick samples in the later stage of diffusion. Moisture permeability of 10mmthick samples was two to three order greater than that of 3mm thick ones, while the time to moisture saturation remained unchanged. With the increase of laminate thickness, moisture saturation increased by 1.4% for C/VE and 7% for G/IPE. The residual flexural strength and ILSS were greater in case of 10mm thick specimens after 200 days of exposure. SEM examination of the fractured specimens showed greater levels of fibre/matrix debonding in 10mm thick specimens.

  19. Finite Element Studies on Free Vibration of Laminated Composite Cylindrical Skew Panels

    Directory of Open Access Journals (Sweden)

    Srinivasa Chikkol Venkateshappa

    2014-01-01

    Full Text Available This paper presents the finite element studies made on free vibration of isotropic and laminated composite cylindrical skew panels. A finite element analysis is performed using CQUAD4 and CQUAD8 elements of MSC/NASTRAN software. The effects of the panel angle, skew angle, aspect ratio, and length-to-thickness-ratio on fundamental natural frequency of vibration of isotropic cylindrical skew panels are studied. The effects of additional parameters such as fiber orientation angle, numbers of layers (keeping total thickness constant, and laminate stacking sequence on the fundamental frequency of vibration of antisymmetric composite laminates have also been studied. During validation and convergence study, it is found that the CQUAD8 element yields more accurate results than the CQUAD4 element. Hence the CQUAD8 element has been employed for the remaining part of the investigation. The fundamental frequency is found to increase with the panel angle and skew angle. The variation of the fundamental frequency with the number of layers is not appreciable when the number of layers is greater than about 6. It is also seen that the boundary conditions have significant influence on the fundamental frequency.

  20. Two Sorts of Fiber Optic Sensor Monitoring the Cure Process of Composite Laminate

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Two new sorts of fiber optic sensor are designed.Firstly, the variation of refractive index of resin surrounding the embedded fiber optic was mean to observed by measuring the speckle spatial spectrum at the end-face of the fiber optic.Secondly, it is proposed to measuring the change of thickness of the laminate by using fiber optic microbend attenuation.The experiment results measured by the fiber optic sensors are given.The first sort of sensor was found to be able to detect the viscosity process of the resin matrix during cure process includeing the minimum point of viscosity, the gelation point and the end point of cure process; the second sort of sensor could detect the course of change of the thickness of composite laminate pressed by operation pressure.It is benefit for us to optimize the operation technology and to establish the intelligent monitoring system about curing process of composites for the reason that the viscosity process and the change course of the thickness of laminate can be monitored.

  1. Standard test method for translaminar fracture toughness of laminated and pultruded polymer matrix composite materials

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 This test method covers the determination of translaminar fracture toughness, KTL, for laminated and pultruded polymer matrix composite materials of various ply orientations using test results from monotonically loaded notched specimens. 1.2 This test method is applicable to room temperature laboratory air environments. 1.3 Composite materials that can be tested by this test method are not limited by thickness or by type of polymer matrix or fiber, provided that the specimen sizes and the test results meet the requirements of this test method. This test method was developed primarily from test results of various carbon fiber – epoxy matrix laminates and from additional results of glass fiber – epoxy matrix, glass fiber-polyester matrix pultrusions and carbon fiber – bismaleimide matrix laminates (1-4, 6, 7). 1.4 A range of eccentrically loaded, single-edge-notch tension, ESE(T), specimen sizes with proportional planar dimensions is provided, but planar size may be variable and adjusted, with asso...

  2. Fabrication of laminated ZrC-SiC composite by vacuum hot-pressing sintering

    Directory of Open Access Journals (Sweden)

    Yuanyuan Li

    2015-03-01

    Full Text Available Laminated ZrC-SiC ceramic was prepared through tape casting and hot pressing. The green tapes of ZrC and SiC were prepared at room temperature. In order to improve the density of composite, the binder of green tapes were removed at 550 °C for 1 h. The laminated structure and the cracks propagation path, which is not a straight line, are observed by optical metalloscope. The compact laminated ZrC-SiC composite sintered by vacuum hot-pressing at 1650 °C for 90 min under pressure of 20 MPa was researched by X-ray diffraction and scanning electron microscopy (SEM equipped with energy dispersive X-ray analysis. The results showed that interlayer bonding is tight, and no disordered phase has formed in the interlayers of ZrC or SiC, and the combination mode is physical mechanism.

  3. On micro-meso relations homogenizing electrical properties of transversely cracked laminated composites

    KAUST Repository

    Lubineau, Gilles

    2013-11-01

    A practical way to track the development of transverse cracking in a laminated composite is to monitor the change of its electrical resistance. Yet, the relations between transverse cracking and the global modification of resistivity is still unclear that makes difficult to interpret these non-destructive-testing results. Here, we introduce the homogenization process that defines at the meso scale an equivalent homogeneous ply that is energetically equivalent to the cracked one. It is shown that this equivalent ply mainly depends on the cracking level while it can be considered independent on the rest of the laminated structure. The direct consequence is that the meso scale is a pertinent one to perform the homogenization. Then, non-destructive electrical measurements can be considered as a reliable technique to access meso scale damage indicators. © 2013 Elsevier Ltd.

  4. Electrical behavior of laminated composites with intralaminar degradation: A comprehensive micro-meso homogenization procedure

    KAUST Repository

    Selvakumaran, Lakshmi

    2014-03-01

    Electrical Resistance Tomography (ERT) is a promising health monitoring technique to assess damage in laminated composites. Yet, the missing link between the various complex degradation mechanisms within the laminate and its global change in resistivity prevents ERT from being used as a quantitative technique. We propose an electrical mesomodel that can establish this link between the various microscale degradations and the resistivity changes in the measurements. The mesoscale homogenization of transverse cracks with local delamination of the ply is first described for in-plane electrical loading for both the outer and the inner plies. The mesoscale model is then extended to include the out-of-plane loading. The relationship between the mesoscale damage indicators and the degradation morphology is identified. These damage indicators are found to be intrinsic to the ply. As such, this defines the first step towards the interpretation of resistivity measurement in terms of micromechanical damage. © 2013 Elsevier Ltd.

  5. Modified Adomian decomposition method for fracture of laminated uni-directional composites

    Indian Academy of Sciences (India)

    B K Raghu Prasad; P V Ramana

    2012-02-01

    In this paper, the well-known Adomian Decomposition Method (ADM) is modified to solve the fracture laminated multi-directional problems. The results are compared with the existing analytical/exact or experimental method. The already known existing ADM is modified to improve the accuracy and convergence. Thus, the modified method is named as Modified Adomian Decomposition Method (MADM). The results from MADM are found to converge very quickly, simple to apply for fracture(singularity) problems and are more accurate compared to experimental and analytical methods. MADM is quite efficient and is practically well-suited for use in these problems. Several examples are given to check the reliability of the present method. In the present paper, the principle of the decomposition method is described, and its advantages form the analyses of fracture of laminated uni-directional composites.

  6. Deflection and Vibration Control of Laminated Plates Using Extension and Shear Actuated Fiber Composites

    Directory of Open Access Journals (Sweden)

    S. Raja

    2011-01-01

    Full Text Available The use of surface bonded and embedded piezoelectric composite actuators is examined through a numerical study. Modelling schemes are therefore developed by applying the isoparametric finite element approach to idealise extension-bending and shear-bending couplings due to piezoelectric actuations. A modal control based linear quadratic regulator is employed to perform the active vibration control studies. Influence of shear actuation direction and its width has been examined and interesting deflection patterns are noticed. The through width SAFC develops a constant deflection beyond its length along the laminated plate length. In contrast, segmented SAFC produces a moderate to linearly varying deflection pattern. MFC actuators have shown promising features in vibration control performances. Nevertheless, closed loop damping presents the efficiency of SAFC in the vibration control application. It is therefore envisaged that optimally actuated smart laminates can be designed using MFC and SAFC to efficiently counteract the disturbance forces.

  7. Thermo-oxidative degradation of graphite/epoxy composite laminates: Modeling and long-term predictions

    Directory of Open Access Journals (Sweden)

    2009-12-01

    Full Text Available Thermo-oxidative degradation of graphite/epoxy composite laminates due to exposure to elevated temperatures was characterized using weight loss and short beam strength (SBS reduction data. Test specimens obtained from 24-ply, unidirectional AS4/3501-6 graphite/epoxy laminates were subjected to 100, 150, 175, and 200°C for 5000 hours (208 days in air. Predictive differential models for the weight loss and short beam strength reduction were developed using the isothermal degradation data only up to 2000 hours. Then, the predictive capabilities of both models were demonstrated using the longer term, 5000 hours degradation data. The proposed models were first order differential expressions that can be used to predict degradation in an arbitrary, time-dependent temperature environment. Both models were able to estimate the actual degradation levels accurately. In particular, excellent agreement was obtained when the degradation temperature was lower than 200°C.

  8. Thickness filters for gradient based multi-material and thickness optimization of laminated composite structures

    DEFF Research Database (Denmark)

    Sørensen, Rene; Lund, Erik

    2015-01-01

    This paper presents a new gradient based method for performing discrete material and thickness optimization of laminated composite structures. The novelty in the new method lies in the application of so-called casting constraints, or thickness filters in this context, to control the thickness...... govern the presence of material in each layer through the thickness of the laminate. Combined with an in-plane density filter, the method enables manufacturers to control the length scale of the geometry while obtaining near discrete designs. Together with the applied manufacturing constraints it is now...... possible for manufacturers to steer the design towards a higher level of manufacturability. The method is demonstrated for mass minimization with displacement and manufacturing constraints. The results show that the method indeed is capable of obtaining near discrete designs which obey the governing...

  9. Probabilistic fracture investigation of symmetric angle ply laminated composite plates using displacement correlation method

    Directory of Open Access Journals (Sweden)

    Lal Achchhe

    2016-01-01

    Full Text Available The second order statistics of mixed mode stress intensity factors (MSIF of single edge V-notched angle ply laminated composite plate subjected to uniaxial tensile load with uncertinity in the system properties using displacement correlation method (DCM is evaluated. The random system properties such as material properties, crack opening and crack length are modelled as combined uncorrelated and correlated random system variables. A C0 finite element method (FEM based on higher order shear deformation plate theory (HSDT is used for basic formulation. The Taylor series based first order perturbation technique (FOPT, second order perturbation technique (SOPT are used and direct Monte Carlo simulation (MCS is performed to evaluate the statistics (mean and coefficient of variance of the mixed mode SIFs. The present work signifies the accurate analysis of frature behaviour by influence of different random variables and fibre orientations on the fracture behaviour in angle ply laminates.

  10. A Nonlinear Finite Element Method for Magnetoelectric Composite and the Study on the Influence of Interfacial Bonding

    Directory of Open Access Journals (Sweden)

    He-Ling Wang

    2013-01-01

    Full Text Available Magnetoelectric composite material is effective in transferring magnetic field into electric signal. In this paper, a nonlinear finite element method is present to model the magnetoelectric composite of ferroelectric and magnetostrictive material. In the method, the nonlinear and coupling behavior of magnetostrictive material such as Terfenol-D is considered. The nonuniform magnetic, electric, and mechanical field distributions are present. An interfacial transferring coefficient is defined to investigate the performance of interfacial mechanical coupling quantitatively, and the influence of the properties of interfacial bonding material and interfacial cracks on magnetoelectric coefficient is discussed. A new laminate ME composite of curved interface is proposed to overcome weak interfacial bonding.

  11. Detection of Fatigue Crack in Basalt FRP Laminate Composite Pipe using Electrical Potential Change Method

    Science.gov (United States)

    Altabey, Wael A.; Noori, Mohammed

    2017-05-01

    Novel modulation electrical potential change (EPC) method for fatigue crack detection in a basalt fibre reinforced polymer (FRP) laminate composite pipe is carried out in this paper. The technique is applied to a laminate pipe with an embedded crack in three layers [0º/90º/0º]s. EPC is applied for evaluating the dielectric properties of basalt FRP pipe by using an electrical capacitance sensor (ECS) to discern damages in the pipe. Twelve electrodes are mounted on the outer surface of the pipe and the changes in the modulation dielectric properties of the piping system are analyzed to detect damages in the pipe. An embedded crack is created by a fatigue internal pressure test. The capacitance values, capacitance change and node potential distribution of ECS electrodes are calculated before and after crack initiates using a finite element method (FEM) by ANSYS and MATLAB, which are combined to simulate sensor characteristics and fatigue behaviour. The crack lengths of the basalt FRP are investigated for various number of cycles to failure for determining crack growth rate. Response surfaces are adopted as a tool for solving inverse problems to estimate crack lengths from the measured electric potential differences of all segments between electrodes to validate the FEM results. The results show that, the good convergence between the FEM and estimated results. Also the results of this study show that the electrical potential difference of the basalt FRP laminate increases during cyclic loading, caused by matrix cracking. The results indicate that the proposed method successfully provides fatigue crack detection for basalt FRP laminate composite pipes.

  12. Copper laminated composites reinforced with Al2O3 nanoparticles by suspension method and hot pressing

    Science.gov (United States)

    Roudini, G.; Ghahfarokhi, A. Rasti; Behzadmehr, A.

    2017-05-01

    Laminated composite of copper with alumina nanoparticle reinforcements has application such as electrical industries. Electrical junctions should have high electrical, thermal conductivity with good mechanical strength. In this research the layers interface of pure copper were reinforced by alumina nanoparticles. For the production of the composite, first alumina nanoparticles were dispersed on Cu layers by suspension method and then the layers were hot pressed at 950°C under 20 MPa pressure. After composite making, the microstructure, the tensile and impact of these composite were studied. The results showed that by increasing amount of alumina nanoparticles up to 0. 5 wt %, tensile and impact strength were increased and for the composites with more than 0.5 wt % because of agglomeration of nanoparticles, these properties were decreased.

  13. Stress Concentration Study of Laminated Composite with Multiple Holes by Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Anand.A

    2016-10-01

    Full Text Available A “Composite” is considered as one material when two or more different materials combined together to create superior material. A composite laminate is a composite with combination of layers. They have great applications in many engineering domains like civil, marine, aerospace, biomedical etc. because of their excellent properties like low weight, better mechanical properties and ease of handling and low cost of production. The practical applications of composites enables that the composite structures usually consist cutouts in it in order to get the required design. Thus it is essential to study the behaviour of composites with multiple holes with respect to different applications in order to provide structural stability and to attain better design and mechanical Properties. This work presents Analytical and Finite Element Analysis of rectangular plate with and without multiple circular cut-outs of various sizes. The work is checked for deformation and stress obtained for various loads .The material considered was Glass/Epoxy laminate. The deformation and stress distribution for various loads is analysed by Ansys software. The specimens used are plate without hole, plate with 3 holes of 5mm each, plate with 6mm holes, plate with 8mm holes and plate with 10mm holes. The analytical and numerical results are compared in Stress - Strain curves and Load - Deformation curves and found that both are in good agreement

  14. Ballistic Impact Response of Ceramic-Faced Aramid Laminated Composites Against 7.62 mm Armour Piercing Projectiles

    Directory of Open Access Journals (Sweden)

    Nityananda Nayak

    2013-07-01

    Full Text Available Ballistic impact response of ceramic- composite armor, consisting of zirconia toughened alumina (ZTA ceramic front and aramid laminated composite as backing, against 7.62 mm armor piercing (AP projectiles has been studied. Two types of backing composite laminates i.e. Twaron-epoxy and Twaron-polypropylene (PP of 10 mm and 15 mm thickness were used with a ceramic face of 4mm thick ZTA. The ceramic- faced and the stand alone composite laminates were subjected to ballistic impact of steel core 7.62 mm AP projectiles with varying impact velocities and their V50 ballistic limit (BL was determined. A sharp rise in BL was observed due to addition of ceramic front layer as compared to stand alone ones. The impact energy was absorbed during penetration primarily by fracture of ceramic, deformation and fracture of projectile and elastic-plastic deformation of flexible backing composite layer. The breaking of ceramic tiles were only limited to impact area and did not spread to whole surface and projectile shattering above BL and blunting on impact below BL was observed. The ceramic- faced composites showed higher BL with Twaron-PP as backing than Twaron-epoxy laminate of same thickness. This combination of ceramic-composite laminates exhibited better multi-hit resistance capability; ideal for light weight armor.Defence Science Journal, 2013, 63(4, pp.369-375, DOI:http://dx.doi.org/10.14429/dsj.63.2616

  15. Large-Amplitude Free Flexural Vibrations of Laminated Composite Curved Panels using Shear-Flexible Shell Element

    Directory of Open Access Journals (Sweden)

    M. Ganapathi

    1995-01-01

    Full Text Available Using degree centigrade continuous, QUAD-8 shear-flexible shell element, based on field consistency principle, the nonlinear free flexural vibrations of anisotropic laminated curved panels are studied. The formulation includes transverse shear deformation, in-plane and rotary inertia effects and geometrical nonlinearity. The element is employed to study the large amplitude dynamic behaviour of cylindrical and spherical shells. The frequency versus amplitude curves are obtained from the dynamic response history. The nonlinear governing equations are solved using Wilson-Theta numerical integration scheme with Theta = 1.4. For each time step, modified Newton-Raphson iterations are employed to achieve equilibrium at the end of that time step. Detailed numerical results are presented, showing the effects of thickness, lamination scheme, material properties and boundary conditions, on nonlinear behaviour.

  16. Static and dynamic strain energy release rates in toughened thermosetting composite laminates

    Science.gov (United States)

    Cairns, Douglas S.

    1992-01-01

    In this work, the static and dynamic fracture properties of several thermosetting resin based composite laminates are presented. Two classes of materials are explored. These are homogeneous, thermosetting resins and toughened, multi-phase, thermosetting resin systems. Multi-phase resin materials have shown enhancement over homogenous materials with respect to damage resistance. The development of new dynamic tests are presented for composite laminates based on Width Tapered Double Cantilevered Beam (WTDCB) for Mode 1 fracture and the End Notched Flexure (ENF) specimen. The WTDCB sample was loaded via a low inertia, pneumatic cylinder to produce rapid cross-head displacements. A high rate, piezo-electric load cell and an accelerometer were mounted on the specimen. A digital oscilloscope was used for data acquisition. Typical static and dynamic load versus displacement plots are presented. The ENF specimen was impacted in three point bending with an instrumented impact tower. Fracture initiation and propagation energies under static and dynamic conditions were determined analytically and experimentally. The test results for Mode 1 fracture are relatively insensitive to strain rate effects for the laminates tested in this study. The test results from Mode 2 fracture indicate that the toughened systems provide superior fracture initiation and higher resistance to propagation under dynamic conditions. While the static fracture properties of the homogeneous systems may be relatively high, the apparent Mode 2 dynamic critical strain energy release rate drops significantly. The results indicate that static Mode 2 fracture testing is inadequate for determining the fracture performance of composite structures subjected to conditions such as low velocity impact. A good correlation between the basic Mode 2 dynamic fracture properties and the performance is a combined material/structural Compression After Impact (CAI) test is found. These results underscore the importance of

  17. Identification of impact force acting on composite laminated plates using the radiated sound measured with microphones

    Science.gov (United States)

    Atobe, Satoshi; Nonami, Shunsuke; Hu, Ning; Fukunaga, Hisao

    2017-09-01

    Foreign object impact events are serious threats to composite laminates because impact damage leads to significant degradation of the mechanical properties of the structure. Identification of the location and force history of the impact that was applied to the structure can provide useful information for assessing the structural integrity. This study proposes a method for identifying impact forces acting on CFRP (carbon fiber reinforced plastic) laminated plates on the basis of the sound radiated from the impacted structure. Identification of the impact location and force history is performed using the sound pressure measured with microphones. To devise a method for identifying the impact location from the difference in the arrival times of the sound wave detected with the microphones, the propagation path of the sound wave from the impacted point to the sensor is examined. For the identification of the force history, an experimentally constructed transfer matrix is employed to relate the force history to the corresponding sound pressure. To verify the validity of the proposed method, impact tests are conducted by using a CFRP cross-ply laminate as the specimen, and an impulse hammer as the impactor. The experimental results confirm the validity of the present method for identifying the impact location from the arrival time of the sound wave detected with the microphones. Moreover, the results of force history identification show the feasibility of identifying the force history accurately from the measured sound pressure using the experimental transfer matrix.

  18. The Effect of Delamination on Damage Path and Failure Load Prediction for Notched Composite Laminates

    Science.gov (United States)

    Satyanarayana, Arunkumar; Bogert, Philip B.; Chunchu, Prasad B.

    2007-01-01

    The influence of delamination on the progressing damage path and initial failure load in composite laminates is investigated. Results are presented from a numerical and an experimental study of center-notched tensile-loaded coupons. The numerical study includes two approaches. The first approach considers only intralaminar (fiber breakage and matrix cracking) damage modes in calculating the progression of the damage path. In the second approach, the model is extended to consider the effect of interlaminar (delamination) damage modes in addition to the intralaminar damage modes. The intralaminar damage is modeled using progressive damage analysis (PDA) methodology implemented with the VUMAT subroutine in the ABAQUS finite element code. The interlaminar damage mode has been simulated using cohesive elements in ABAQUS. In the experimental study, 2-3 specimens each of two different stacking sequences of center-notched laminates are tensile loaded. The numerical results from the two different modeling approaches are compared with each other and the experimentally observed results for both laminate types. The comparisons reveal that the second modeling approach, where the delamination damage mode is included together with the intralaminar damage modes, better simulates the experimentally observed damage modes and damage paths, which were characterized by splitting failures perpendicular to the notch tips in one or more layers. Additionally, the inclusion of the delamination mode resulted in a better prediction of the loads at which the failure took place, which were higher than those predicted by the first modeling approach which did not include delaminations.

  19. Guided wave and damage detection in composite laminates using different fiber optic sensors.

    Science.gov (United States)

    Li, Fucai; Murayama, Hideaki; Kageyama, Kazuro; Shirai, Takehiro

    2009-01-01

    Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber reinforced plastic (CFRP) laminate and acquired by these fiber optic sensors. Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared. Results demonstrated that both the FBG and FOD sensors can be applied in guided wave and damage detection for the CFRP laminates. The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection. Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH(0)) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent.

  20. Guided Wave and Damage Detection in Composite Laminates Using Different Fiber Optic Sensors

    Directory of Open Access Journals (Sweden)

    Fucai Li

    2009-05-01

    Full Text Available Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG and Doppler effect-based fiber optic (FOD sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber reinforced plastic (CFRP laminate and acquired by these fiber optic sensors. Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared. Results demonstrated that both the FBG and FOD sensors can be applied in guided wave and damage detection for the CFRP laminates. The signal-to-noise ratio (SNR of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection. Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH0 guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent.

  1. Standard Guide for Acousto-Ultrasonic Assessment of Composites, Laminates, and Bonded Joints

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This guide explains the rationale and basic technology for the acousto-ultrasonic (AU) method. Guidelines are given for nondestructive evaluation (NDE) of flaws and physical characteristics that influence the mechanical properties and relative strength of composite structures (for example, filament-wound pressure vessels), adhesive bonds (for example, joints between metal plates), and interlaminar and fiber/matrix bonds in man-made composites and natural composites (for example, wood products). 1.2 This guide covers technical details and rules that must be observed to ensure reliable and reproducible quantitative AU assessments of laminates, composites, and bonded structures. The underlying principles, prototype apparatus, instrumentation, standardization, examination methods, and data analysis for such assessments are covered. Limitations of the AU method and guidelines for taking advantage of its capabilities are cited. 1.3 The objective of AU is to assess subtle flaws and associated strength variations...

  2. Phased array beamforming and imaging in composite laminates using guided waves

    Science.gov (United States)

    Tian, Zhenhua; Leckey, Cara A. C.; Yu, Lingyu

    2016-04-01

    This paper presents the phased array beamforming and imaging using guided waves in anisotropic composite laminates. A generic phased array beamforming formula is presented, based on the classic delay-and-sum principle. The generic formula considers direction-dependent guided wave properties induced by the anisotropic material properties of composites. Moreover, the array beamforming and imaging are performed in frequency domain where the guided wave dispersion effect has been considered. The presented phased array method is implemented with a non-contact scanning laser Doppler vibrometer (SLDV) to detect multiple simulated defects at different locations in an anisotropic composite plate. The array is constructed of scan points in a small area rapidly scanned by the SLDV. Using the phased array method, multiple simulated defects at different locations are successfully detected. Our study shows that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures.

  3. Mechanical properties and failure mechanisms of carbon fiber reinforced epoxy laminated composites

    Energy Technology Data Exchange (ETDEWEB)

    Thissell, W.R.; Zurek, A.K.; Addessio, F.

    1995-09-01

    The mechanical behavior of quasi-isotropic and unidirectional epoxy-matrix carbon-fiber laminated composites subjected compressive loading at strain rates of 10{sup {minus}3} and 2000 s{sup {minus}1} are described. Failure in the studied composites was dominated by delamination which proceeded by brittle fracture of the epoxy-matrix. The matrix-fiber bonding in these composites is very strong and prevented the occurrence of significant fiber-pullout. The mode I delamination strain energy release rate of the unidirectional composites was determined using the double cantilever beam and hole in plate compression method. The DCB method indicated a significant R curve effect attributed to fiber bridging while the presently available hole in plate analytical methods show questionable validity for highly anisotropic materials.

  4. Mechanical properties, microscopy, and failure mechanisms of carbon fiber reinforced epoxy laminated composites

    Energy Technology Data Exchange (ETDEWEB)

    Thissell, W.R.; Zurek, A.K.; Addessio, F.

    1995-12-31

    The mechanical behavior of quasi-isotropic and unidirectional epoxy- matrix carbon-fiber laminated composites subjected to compressive loading at strain rates of 10{sup {minus}3} and 2000 s{sup {minus}1} are described. Failure in the studied composites was dominated by delamination which proceeded by brittle fracture of the epoxy matrix. The matrix-fiber bonding in these composites is very strong and prevented the occurrence of significant fiber-pullout. The mode I delamination strain energy release rate of the unidirectional composites was determined using the double cantilever beam and hole in plate compression methods. The DCB method indicated a significant R curve effect attributed to fiber bridging while the presently available hole in plate analytical methods show questionable validity for highly anisotropic materials.

  5. Nonlinear dynamic response and active control of fiber metal laminated plates with piezoelectric actuators and sensors in unsteady temperature field

    Science.gov (United States)

    Shao, Xuefei; Fu, Yiming; Chen, Yang

    2015-05-01

    Based on the higher order shear deformation theory and the geometric nonlinear theory, the nonlinear motion equations, to which the effects of the positive and negative piezoelectric and the thermal are introduced by piezoelectric fiber metal laminated (FML) plates in an unsteady temperature, are established by Hamilton’s variational principle. Then, the control algorithm of negative-velocity feedback is applied to realize the vibration control of the piezoelectric FML plates. During the solving process, firstly, the formal functions of the displacements that fulfilled the boundary conditions are proposed. Then, heat conduction equations and nonlinear differential equations are dealt with using the differential quadrature (DQ) and Galerkin methods, respectively. On the basis of the previous processing, the time domain is dispersed by the Newmark-β method. Finally, the whole problem can be investigated by the iterative method. In the numerical examples, the influence of the applied voltage, the temperature loading and geometric parameters on the nonlinear dynamic response of the piezoelectric FML plates is analyzed. Meanwhile, the effect of feedback control gain and the position of the piezoelectric layer, the initial deflection and the external temperature on the active control effect of the piezoelectric layers has been studied. The model development and the research results can serve as a basis for nonlinear vibration analysis of the FML structures.

  6. The Effect of Temperature Dependent Material Nonlinearities on the Response of Piezoelectric Composite Plates

    Science.gov (United States)

    Lee, Ho-Jun; Saravanos, Dimitris A.

    1997-01-01

    Previously developed analytical formulations for piezoelectric composite plates are extended to account for the nonlinear effects of temperature on material properties. The temperature dependence of the composite and piezoelectric properties are represented at the material level through the thermopiezoelectric constitutive equations. In addition to capturing thermal effects from temperature dependent material properties, this formulation also accounts for thermal effects arising from: (1) coefficient of thermal expansion mismatch between the various composite and piezoelectric plies and (2) pyroelectric effects on the piezoelectric material. The constitutive equations are incorporated into a layerwise laminate theory to provide a unified representation of the coupled mechanical, electrical, and thermal behavior of smart structures. Corresponding finite element equations are derived and implemented for a bilinear plate element with the inherent capability to model both the active and sensory response of piezoelectric composite laminates. Numerical studies are conducted on a simply supported composite plate with attached piezoceramic patches under thermal gradients to investigate the nonlinear effects of material property temperature dependence on the displacements, sensory voltages, active voltages required to minimize thermal deflections, and the resultant stress states.

  7. Evaluation of the Performance of New Laminated Composite Shells for Motorcycle Helmets

    Directory of Open Access Journals (Sweden)

    Nermin M. Aly

    2015-04-01

    Full Text Available Motorcycles are considered a cost-effective and major means of transportation, particularly in the developing countries. However, motorcyclists are at higher risk of head and brain injuries in road crashes, which is the primarily cause of most of the fatalities occurred. Wearing a protective helmet is an efficient way for the safety of the motorcyclist, since it reduces the severity of head injuries through absorbing the impact energy during accidents. The main components of the helmet are the outer shell and the shock absorbing foam liner. The helmet performance depends to a great extent on the enhancement of the properties of the materials used to provide protection. This paper studied experimentally the protection performance of new laminated composite shells compared with that of an Acrylonitrile Butadiene Styrene (ABS shell. The shell prototypes were fabricated in the form of an open face helmet, composed of a laminated composite structure reinforced with various fabric performs and materials. Expanded polystyrene foam was used for the shock absorbing liner and its compressive properties were examined. The shell prototypes including the foam liner were tested mechanically to investigate their damage behaviour under applying low velocity impacts and penetration loads. Non Destructive Inspection (NDI methods were used, such as visual inspection and X-ray radiography to detect and evaluate the damages found in the prototypes. It was illustrated that, the laminated composite shell reinforced with the polyester/glass woven fabric and glass fiber mat achieved the best performance, can sustain impact loads and provide better protection to the head from penetration. When compared it with the ABS helmet, it approaches to its effectiveness in protection and the produced shell prototypes are promising for using in motorcycling.

  8. An optimal modeling of multidimensional wave digital filtering network for free vibration analysis of symmetrically laminated composite FSDT plates

    Science.gov (United States)

    Tseng, Chien-Hsun

    2015-02-01

    The technique of multidimensional wave digital filtering (MDWDF) that builds on traveling wave formulation of lumped electrical elements, is successfully implemented on the study of dynamic responses of symmetrically laminated composite plate based on the first order shear deformation theory. The philosophy applied for the first time in this laminate mechanics relies on integration of certain principles involving modeling and simulation, circuit theory, and MD digital signal processing to provide a great variety of outstanding features. Especially benefited by the conservation of passivity gives rise to a nonlinear programming problem (NLP) for the issue of numerical stability of a MD discrete system. Adopting the augmented Lagrangian genetic algorithm, an effective optimization technique for rapidly achieving solution spaces of NLP models, numerical stability of the MDWDF network is well received at all time by the satisfaction of the Courant-Friedrichs-Levy stability criterion with the least restriction. In particular, optimum of the NLP has led to the optimality of the network in terms of effectively and accurately predicting the desired fundamental frequency, and thus to give an insight into the robustness of the network by looking at the distribution of system energies. To further explore the application of the optimum network, more numerical examples are engaged in efforts to achieve a qualitative understanding of the behavior of the laminar system. These are carried out by investigating various effects based on different stacking sequences, stiffness and span-to-thickness ratios, mode shapes and boundary conditions. Results are scrupulously validated by cross referencing with early published works, which show that the present method is in excellent agreement with other numerical and analytical methods.

  9. Shear-flexible finite-element models of laminated composite plates and shells

    Science.gov (United States)

    Noor, A. K.; Mathers, M. D.

    1975-01-01

    Several finite-element models are applied to the linear static, stability, and vibration analysis of laminated composite plates and shells. The study is based on linear shallow-shell theory, with the effects of shear deformation, anisotropic material behavior, and bending-extensional coupling included. Both stiffness (displacement) and mixed finite-element models are considered. Discussion is focused on the effects of shear deformation and anisotropic material behavior on the accuracy and convergence of different finite-element models. Numerical studies are presented which show the effects of increasing the order of the approximating polynomials, adding internal degrees of freedom, and using derivatives of generalized displacements as nodal parameters.

  10. Hybrid Finite Element Analysis of Free Edge Effect in Symmetric Composite Laminates

    Science.gov (United States)

    1983-06-01

    ANALYSIS OF FREE EDGE EFFECT IN L AUTHOR(S 61102F S.W. Lee237B J.J. Rhiu S.C. Won,, I ~ 7. PENOAMnG ORGANIZATION NAME(S) AND ADORES4 S) L. PERFORMING...ANALYSIS OF FREE EDGE EFFECT IN SYMMETRIC COMPOSITE LAMINATES S. W. Lee I 3. Phi S. C. Wong Department of Aerospace Engineering University of Maryland...collocation method. In this report, we present an efficient hybrid finite element method for analysis of interlaminar stress or free edge effect in

  11. Mixed-mode fracture in unidirectional graphite epoxy composite laminates with central notch

    Science.gov (United States)

    Binienda, Wieslaw K.; Reddy, E. S.

    1992-01-01

    Mixed-mode matrix fracture in central notched off-axis unidirectional composite laminates was investigated. A limited number of unidirectional tensile type specimens with a central, horizontal, notch were tested. Crack initiation and propagation were examined under various local stress fields that were controlled by fiber orientations. The tested specimens were simulated using a two dimensional finite element method with constant strain loading. The strain energy release rates along the crack were evaluated via crack closure technique. The variation of critical strain energy rates with off-axis angle was studied. The results from single (one-sided) and double (two-sided) crack simulations were presented and compared.

  12. Finite strip analysis of anisotropic laminated composite plates using higher-order shear deformation theory

    Science.gov (United States)

    Akhras, G.; Cheung, M. S.; Li, W.

    1994-08-01

    In the present study, a finite strip method for the elastic analysis of anisotropic laminated composite plates is developed according to higher-order shear deformation theory. This theory accounts for the parabolic distribution of the transverse shear strains through the thickness of the plate and for zero transverse shear stresses on the plate surfaces. In comparison with the finite strip method based on first-order shear deformation theory, the present method gives improved results while using approximately the same number of degrees of freedom. It also eliminates the need for shear correction factors in calculating the transverse shear stiffness.

  13. Multi-material topology optimization of laminated composite beams with eigenfrequency constraints

    DEFF Research Database (Denmark)

    Blasques, José Pedro Albergaria Amaral

    2014-01-01

    This paper describes a methodology for simultaneous topology and material optimization in optimal design of laminated composite beams with eigenfrequency constraints. The structural response is analyzed using beam finite elements. The beam sectional properties are evaluated using a finite element...... based cross section analysis tool which is able to account for effects stemming from material anisotropy and inhomogeneity in sections of arbitrary geometry. The optimization is performed within a multi-material topology optimization framework where the continuous design variables represent the volume....... The results suggest that the devised methodology is suitable for simultaneous optimization of the cross section topology and material properties in design of beams with eigenfrequency constraints....

  14. Microtomographic Analysis of Impact Damage in FRP Composite Laminates: A Comparative Study

    Directory of Open Access Journals (Sweden)

    M. Alemi-Ardakani

    2013-01-01

    Full Text Available With the advancement of testing tools, the ability to characterize mechanical properties of fiber reinforced polymer (FRP composites under extreme loading scenarios has allowed designers to use these materials in high-level applications more confidently. Conventionally, impact characterization of composite materials is studied via nondestructive techniques such as ultrasonic C-scanning, infrared thermography, X-ray, and acoustography. None of these techniques, however, enable 3D microscale visualization of the damage at different layers of composite laminates. In this paper, a 3D microtomographic technique has been employed to visualize and compare impact damage modes in a set of thermoplastic laminates. The test samples were made of commingled polypropylene (PP and glass fibers with two different architectures, including the plain woven and unidirectional. Impact testing using a drop-weight tower, followed by postimpact four-point flexural testing and nondestructive tomographic analysis demonstrated a close relationship between the type of fibre architecture and the induced impact damage mechanisms and their extensions.

  15. Power transmission through double-walled laminated composite panels considering porous layer-air gap insulation

    Institute of Scientific and Technical Information of China (English)

    M H SHOJAEIFARD; R TALEBITOOTI; B RANJBAR; R AHMADI

    2014-01-01

    The acoustic behavior of double-walled laminated composite panels consisting of two porous and air gap middle layers is studied within the classical laminated plate theory (CLPT). Thus, viscous and inertia coupling in a dynamic equation, as well as stress transfer, thermal and elastic coupling of porous material are based on the Biot theory. In addition, the wave equations are extracted according to the vibration equation of composite layers. The transmission loss (TL) of the structure is then calculated by solving these equations simultaneously. Statistical energy analysis (SEA) is developed to divide the structure into specific subsystems, and power transmission is extracted with balancing power flow equations of the subsystems. Comparison between the present work and the results reported elsewhere shows excellent agreement. The results also indicate that, although favorable enhancement is seen in noise control particularly at high frequencies, the corresponding parameters associated with fluid phase and solid phase of the porous layer are important on TL according to the boundary condition interfaces. Finally, the influence of composite material and stacking sequence on power transmission is discussed.

  16. Simultaneous Application of Fibrous Piezoresistive Sensors for Compression and Traction Detection in Glass Laminate Composites

    Science.gov (United States)

    Nauman, Saad; Cristian, Irina; Koncar, Vladan

    2011-01-01

    This article describes further development of a novel Non Destructive Evaluation (NDE) approach described in one of our previous papers. Here these sensors have been used for the first time as a Piecewise Continuous System (PCS), which means that they are not only capable of following the deformation pattern but can also detect distinctive fracture events. In order to characterize the simultaneous compression and traction response of these sensors, multilayer glass laminate composite samples were prepared for 3-point bending tests. The laminate sample consisted of five layers of plain woven glass fabrics placed one over another. The sensors were placed at two strategic locations during the lay-up process so as to follow traction and compression separately. The reinforcements were then impregnated in epoxy resin and later subjected to 3-point bending tests. An appropriate data treatment and recording device has also been developed and used for simultaneous data acquisition from the two sensors. The results obtained, under standard testing conditions have shown that our textile fibrous sensors can not only be used for simultaneous detection of compression and traction in composite parts for on-line structural health monitoring but their sensitivity and carefully chosen location inside the composite ensures that each fracture event is indicated in real time by the output signal of the sensor. PMID:22163707

  17. STACKING SEQUENCE OPTIMIZATION OF LAMINATED COMPOSITE CYLINDER SHELL FOR MAXIMAL BUCKLING LOAD

    Institute of Scientific and Technical Information of China (English)

    TANG Qian; LIAO Xiaoyun; GAO Zhan

    2008-01-01

    A new optimization method for the optimization of stacking of composite glass fiber laminates is developed. The fiber orientation and angle of the layers of the cylindrical shells are sought considering the buckling load. The proposed optimization algorithm applies both finite element analysis and the mode-pursuing sampling (MPS)method. The algorithms suggest the optimal stacking sequence for achieving the maximal buckling load. The procedure is implemented by integrating ANSYS and MATLAB. The stacking sequence designing for the symmetric angle-ply three-layered and five-layered composite cylinder shells is presented to illustrate the optimization process, respectively. Compared with the genetic algorithms, the proposed optimization method is much faster and efficient for composite staking sequence plan.

  18. Application of the Refined Zigzag Theory to the Modeling of Delaminations in Laminated Composites

    Science.gov (United States)

    Groh, Rainer M. J.; Weaver, Paul M.; Tessler, Alexander

    2015-01-01

    The Refined Zigzag Theory is applied to the modeling of delaminations in laminated composites. The commonly used cohesive zone approach is adapted for use within a continuum mechanics model, and then used to predict the onset and propagation of delamination in five cross-ply composite beams. The resin-rich area between individual composite plies is modeled explicitly using thin, discrete layers with isotropic material properties. A damage model is applied to these resin-rich layers to enable tracking of delamination propagation. The displacement jump across the damaged interfacial resin layer is captured using the zigzag function of the Refined Zigzag Theory. The overall model predicts the initiation of delamination to within 8% compared to experimental results and the load drop after propagation is represented accurately.

  19. Effect of Static and Cyclic Loading on Ceramic Laminate Veneers Adhered to Teeth with and Without Aged Composite Restorations

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Ozcan, Mutlu; Kalk, Warner; Galhano, Graziela

    2011-01-01

    Purpose: Existing composite restorations on teeth are often remade prior to the cementation of fixed dental prostheses. The aim of this study was to evaluate the effect of static and cyclic loading on ceramic laminate veneers adhered to aged resin composite restorations. Materials and Methods: Eight

  20. Fracture Strength of Indirect Resin Composite Laminates to Teeth with Existing Restorations : An Evaluation of Conditioning Protocols

    NARCIS (Netherlands)

    Mese, Ayse; Ozcan, Mutlu

    2009-01-01

    Purpose: This study evaluated the fracture strength and failure types of indirect resin-based composite laminates bonded to teeth with aged Class III composite restorations that were conditioned according to various protocols. Materials and Methods: Maxillary central incisors (N = 60) with window-ty

  1. Effect of Static and Cyclic Loading on Ceramic Laminate Veneers Adhered to Teeth with and Without Aged Composite Restorations

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Ozcan, Mutlu; Kalk, Warner; Galhano, Graziela

    2011-01-01

    Purpose: Existing composite restorations on teeth are often remade prior to the cementation of fixed dental prostheses. The aim of this study was to evaluate the effect of static and cyclic loading on ceramic laminate veneers adhered to aged resin composite restorations. Materials and Methods:

  2. Analytical Modelling of Transverse Matrix Cracking of [plus or minus Theta/90(sub n)](sub s) Composite Laminates Under Multiaxial Loading

    Science.gov (United States)

    Mayugo, J A.; Camanho, P. P.; Maimi, P.; Davila, C. G.

    2010-01-01

    An analytical model based on the analysis of a cracked unit cell of a composite laminate subjected to multiaxial loads is proposed to predict the onset and accumulation of transverse matrix cracks in the 90(sub n) plies of uniformly stressed [plus or minus Theta/90(sub n)](sub s) laminates. The model predicts the effect of matrix cracks on the stiffness of the laminate, as well as the ultimate failure of the laminate, and it accounts for the effect of the ply thickness on the ply strength. Several examples describing the predictions of laminate response, from damage onset up to final failure under both uniaxial and multiaxial loads, are presented.

  3. Analytical Modelling of Transverse Matrix Cracking of [plus or minus Theta/90(sub n)](sub s) Composite Laminates Under Multiaxial Loading

    Science.gov (United States)

    Mayugo, J A.; Camanho, P. P.; Maimi, P.; Davila, C. G.

    2010-01-01

    An analytical model based on the analysis of a cracked unit cell of a composite laminate subjected to multiaxial loads is proposed to predict the onset and accumulation of transverse matrix cracks in the 90(sub n) plies of uniformly stressed [plus or minus Theta/90(sub n)](sub s) laminates. The model predicts the effect of matrix cracks on the stiffness of the laminate, as well as the ultimate failure of the laminate, and it accounts for the effect of the ply thickness on the ply strength. Several examples describing the predictions of laminate response, from damage onset up to final failure under both uniaxial and multiaxial loads, are presented.

  4. Investigation of the Mechanical Properties of Hybrid Carbon-Hemp Laminated Composites Used as Thermal Insulation for Different Industrial Applications

    Directory of Open Access Journals (Sweden)

    M. L. Scutaru

    2014-04-01

    Full Text Available Carbon-hemp composite laminate provides good thermal properties. For this reason this type of material is presently being used for various applications like insulator for airplanes, spaceships, nuclear reactors, and so forth. Unfortunately their mechanical properties are less studied. These characteristics are very important since they should be guaranteed also for important mechanical stress in addition to the thermal one. The present paper presents a study regarding the impact testing of some hybrid composite laminate panels based on polyester resin reinforced with both carbon and hemp fabric. The effects of different impact speeds on the mechanical behavior of these panels have been analyzed. The paper lays stress on the characterization of this hybrid composite laminate regarding the impact behavior of these panels by dropping a weight with low velocity.

  5. STUDY ON THE TENSILE FATIGUE DAMAGE OF QUASI-ISOTROPIC COMPOSITE LAMINATES

    Institute of Scientific and Technical Information of China (English)

    I.G.Kim; I.S.Kim; O.S.Kim; Yaragarra K.D.V. Prasad4

    2003-01-01

    Quasi-isotropic laminates have isotropic elastic properties in all in-plane directions.Therefore, this kind of laminate is widely used for structural elements. The simpleststacking sequence of quasi-isotropic laminates is [0/-60/60]s. When the direction ofapplied axial load to [0/-60/60]s laminate is inclined at a 30-degree angle, we havethe other quasi-isotropic laminate [30/-30/90]s under axial load. The failure mecha-nisms of these two laminates are, however, entirely different from each other becausethese two laminates have different distribution of the interlaminar stresses. It wasconfirmed by tensile fatigue tests that the [0/-60/60]s laminate does not show any vis-ible fatigue damage, but the [30/-30/90]s laminate develops edge-delamination duringcyclic loading. The analytical results were in good agreement with the experimental results.

  6. A SIMPLE FINITE ELEMENT FOR NON-LINEAR ANALYSIS OF COMPOSITE PLATES

    Directory of Open Access Journals (Sweden)

    V.B. Tungikar

    2011-06-01

    Full Text Available Finite Element Analysis for geometrically nonlinear behaviour of laminated composite plates is presented andcompared with the reported investigations. However structural non-linearity is encountered in certain cases andneeds attention. A higher order displacement field that accounts for transverse shear effects under geometricnonlinear condition is employed in the formulation of a four node, rectangular, element with thirteen degrees offreedom per node. First order Zigzag terms have been included in displacement field for improvement in theresponse. Von Karman strain approach is considered in the present analysis. Incremental Pica iterative scheme isused to solve resulting nonlinear equilibrium equations. The formulation demonstrates its excellence in theperformance for predicting response at various lay ups and plies conditions.

  7. Vibration Analysis of Inclined Laminated Composite Beams under Moving Distributed Masses

    Directory of Open Access Journals (Sweden)

    E. Bahmyari

    2014-01-01

    Full Text Available The dynamic response of laminated composite beams subjected to distributed moving masses is investigated using the finite element method (FEM based on the both first-order shear deformation theory (FSDT and the classical beam theory (CLT. Six and ten degrees of freedom beam elements are used to discretize the CLT and FSDT equations of motion, respectively. The resulting spatially discretized beam governing equations including the effect of inertial, Coriolis, and centrifugal forces due to moving distributed mass are evaluated in time domain by applying Newmark’s scheme. The presented approach is first validated by studying its convergence behavior and comparing the results with those of existing solutions in the literature. Then, the effect of incline angle, mass, and velocity of moving body, layer orientation, load length, and inertial, Coriolis, and centrifugal forces due to the moving distributed mass and friction force between the beam and the moving distributed mass on the dynamic behavior of inclined laminated composite beams are investigated.

  8. Dynamic stiffness matrix of thin-walled composite I-beam with symmetric and arbitrary laminations

    Science.gov (United States)

    Kim, Nam-Il; Shin, Dong Ku; Park, Young-Suk

    2008-11-01

    For the spatially coupled free vibration analysis of thin-walled composite I-beam with symmetric and arbitrary laminations, the exact dynamic stiffness matrix based on the solution of the simultaneous ordinary differential equations is presented. For this, a general theory for the vibration analysis of composite beam with arbitrary lamination including the restrained warping torsion is developed by introducing Vlasov's assumption. Next, the equations of motion and force-displacement relationships are derived from the energy principle and the first order of transformed simultaneous differential equations are constructed by using the displacement state vector consisting of 14 displacement parameters. Then explicit expressions for displacement parameters are derived and the exact dynamic stiffness matrix is determined using force-displacement relationships. In addition, the finite-element (FE) procedure based on Hermitian interpolation polynomials is developed. To verify the validity and the accuracy of this study, the numerical solutions are presented and compared with analytical solutions, the results from available references and the FE analysis using the thin-walled Hermitian beam elements. Particular emphasis is given in showing the phenomenon of vibrational mode change, the effects of increase of the modulus and the bending-twisting coupling stiffness for beams with various boundary conditions.

  9. Extended Kantorovich method for local stresses in composite laminates upon polynomial stress functions

    Institute of Scientific and Technical Information of China (English)

    Bin Huang; Ji Wang; Jianke Du; Yan Guo; Tingfeng Ma; Lijun Yi

    2016-01-01

    The extended Kantorovich method is employed to study the local stress concentrations at the vicinity of free edges in symmetrically layered composite laminates subjected to uniaxial tensile load upon polynomial stress functions. The stress fields are initially assumed by means of the Lekhnitskii stress functions under the plane strain state. Applying the principle of complementary virtual work, the coupled ordinary differential equations are obtained in which the solutions can be obtained by solving a generalized eigenvalue problem. Then an iterative procedure is estab-lished to achieve convergent stress distributions. It should be noted that the stress function based extended Kantorovich method can satisfy both the traction-free and free edge stress boundary conditions during the iterative processes. The stress components near the free edges and in the interior regions are calculated and compared with those obtained results by finite element method (FEM). The convergent stresses have good agreements with those results obtained by three dimensional (3D) FEM. For generality, various layup configurations are considered for the numerical analysis. The results show that the proposed polynomial stress function based extended Kan-torovich method is accurate and efficient in predicting the local stresses in composite laminates and computationally much more efficient than the 3D FEM.

  10. On the detectability of transverse cracks in laminated composites through measurements of electrical potential change

    KAUST Repository

    Selvakumaran, Lakshmi

    2015-01-07

    For structures made of laminated composites, real-time structural health monitoring is necessary as significant damage may occur without any visible signs on the surface. Inspection by electrical tomography seems a viable approach as the technique relies on voltage measurements from a network of electrodes over the boundary of the inspected domain to infer the change in conductivity within the bulk material. The change in conductivity, if significant, can be correlated to the degradation state of the material, allowing damage detection. We focus here on the detection of the transverse cracking mechanism which modifies the in-plane transverse conductivity of ply. The quality of detection is directly related to the sensitivity of the voltage measurements with respect to the presence of cracks. We demonstrate here from numerical experiments that the sensitivity depends on several parameters, such as the anisotropy in the electrical conductivity of the baseline composite ply or the geometricalparameters of the structure. Based on these results, applicability of electrical tomography to detect transverse cracks in a laminate is discussed.

  11. Acoustic emission evaluation of reinforced concrete bridge beam with graphite composite laminate

    Science.gov (United States)

    Johnson, Dan E.; Shen, H. Warren; Finlayson, Richard D.

    2001-07-01

    A test was recently conducted on August 1, 2000 at the FHwA Non-Destructive Evaluation Validation Center, sponsored by The New York State DOT, to evaluate a graphite composite laminate as an effective form of retrofit for reinforced concrete bridge beam. One portion of this testing utilized Acoustic Emission Monitoring for Evaluation of the beam under test. Loading was applied to this beam using a two-point loading scheme at FHwA's facility. This load was applied in several incremental loadings until the failure of the graphite composite laminate took place. Each loading culminated by either visual crack location or large audible emissions from the beam. Between tests external cracks were located visually and highlighted and the graphite epoxy was checked for delamination. Acoustic Emission data was collected to locate cracking areas of the structure during the loading cycles. To collect this Acoustic Emission data, FHwA and NYSDOT utilized a Local Area Monitor, an Acoustic Emission instrument developed in a cooperative effort between FHwA and Physical Acoustics Corporation. Eight Acoustic Emission sensors were attached to the structure, with four on each side, in a symmetrical fashion. As testing progressed and culminated with beam failure, Acoustic Emission data was gathered and correlated against time and test load. This paper will discuss the analysis of this test data.

  12. Non-Linear Dynamic Deformation of a Piezothermoelastic Laminate with Feedback Control System

    Directory of Open Access Journals (Sweden)

    Masayuki Ishihara

    2014-03-01

    Full Text Available We study the control of free vibration with large amplitude in a piezothermoelastic laminated beam subjected to a uniform temperature with a feedback control system. The analytical model is the symmetrically cross-ply laminated beam composed of the elastic and piezoelectric layers. On the basis of the von Kármán strain and the classical laminate theory, the governing equations for the dynamic behavior are derived. The dynamic behavior is detected by the electric current in the sensor layer through the direct piezoelectric effect. The electric voltage with the magnitude of the current multiplied by the gain is applied to the actuator layer to constitute a feedback control system. The governing equations are reduced by the Galerkin method to a Liénard equation with respect to the representative deflection, and the equation is found to be dependent on the gain and the configuration of the actuator. By introducing the Liénard's phase plane, the equation is analyzed geometrically, and the essential characteristics of the beam and stabilization of the dynamic deformation are demonstrated.

  13. Tracking controller for robot manipulators via composite nonlinear feedback law

    Institute of Scientific and Technical Information of China (English)

    Peng Wendong; Su Jianbo

    2009-01-01

    A composite nonlinear feedback tracking controller for motion control of robot manipulators is de-scribed. The structure of the controller is composed of a composite nonlinear feedback law plus full robot nonlinear dynamics compensation. The stability is carried out in the presence of friction. The controller takes advantage of varying damping ratios induced by the composite nonlinear feedback control, so the transient performance of the closed-loop is remarkably improved. Simulation results demonstrate the feasibility of the proposed method.

  14. An optimal approach to active damping of nonlinear vibrations in composite plates using piezoelectric patches

    Science.gov (United States)

    Saviz, M. R.

    2015-11-01

    In this paper a nonlinear approach to studying the vibration characteristic of laminated composite plate with surface-bonded piezoelectric layer/patch is formulated, based on the Green Lagrange type of strain-displacements relations, by incorporating higher-order terms arising from nonlinear relations of kinematics into mathematical formulations. The equations of motion are obtained through the energy method, based on Lagrange equations and by using higher-order shear deformation theories with von Karman-type nonlinearities, so that transverse shear strains vanish at the top and bottom surfaces of the plate. An isoparametric finite element model is provided to model the nonlinear dynamics of the smart plate with piezoelectric layer/ patch. Different boundary conditions are investigated. Optimal locations of piezoelectric patches are found using a genetic algorithm to maximize spatial controllability/observability and considering the effect of residual modes to reduce spillover effect. Active attenuation of vibration of laminated composite plate is achieved through an optimal control law with inequality constraint, which is related to the maximum and minimum values of allowable voltage in the piezoelectric elements. To keep the voltages of actuator pairs in an allowable limit, the Pontryagin’s minimum principle is implemented in a system with multi-inequality constraint of control inputs. The results are compared with similar ones, proving the accuracy of the model especially for the structures undergoing large deformations. The convergence is studied and nonlinear frequencies are obtained for different thickness ratios. The structural coupling between plate and piezoelectric actuators is analyzed. Some examples with new features are presented, indicating that the piezo-patches significantly improve the damping characteristics of the plate for suppressing the geometrically nonlinear transient vibrations.

  15. Strengthening of RC Beams with Large Openings in Shear by CFRP Laminates: Experiment and 2D Nonlinear Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    S.C. Chin

    2012-05-01

    Full Text Available This study presents the experimental study and numerical analysis of Reinforced Concrete (RC beams with large square openings placed in the shear region, at a distance 0.5d and d away from the support, strengthened by Carbon Fiber Reinforced Polymer (CFRP laminates. This research aims to investigate the strength losses in RC beam due to the presence of large square openings placed at two different locations in shear region. Also, in order to re-gain the beam structural capacity loss due to the openings, strengthening by CFRP laminates around the openings were studied. A total of six RC beams were tested to failure under four point loading including control beams, un-strengthened and strengthened RC beams with large square openings in shear region at a distance 0.5d and d away from the support. The CFRP strengthening configuration considered in this study was a full wrapping system around the square openings. A nonlinear finite element program, ATENA was used to validate the results of the tested beams. Comparisons between the finite element predictions and experimental results in terms of crack patterns and load deflection relationships are presented. The crack pattern results of the finite element model show good agreement with the experimental data. The load midspan deflection curves of the finite element models exhibited a stiffer result compared to the experimental beams. The possible reason may be due to the perfect bond assumption between the concrete and steel reinforcement.

  16. Preparation and Mechanical Properties of Al2O3/Al Laminated Ceramic Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    HUANG Kangming; LI Weixin; XIE Binhuan; RAO Pinggen; PENG Cheng; CHEN Dabo; WU Jianqing

    2011-01-01

    Three series of Al2O3/Al laminated ceramic matrix composites,named SPA,SPV and HP,were fabricated by different methods.SPA and SPV were prepared using Al2O3 slices and Al slurry via screen printing and subsequent heat treatment in air or vacuum.HP samples were made by hot pressing the layered stack of Al foils and Al2O3 slices.SEM and XRD were applied to analyze the microstructure and the interlayer crystal phase.The bending strength,fracture toughness and fracture work of the samples made by the three methods were measured and compared.The results show that the composites have much better toughness and higher fracture work than the Al2O3 slice.Among the samples made by the three methods,the samples made by hot pressing have the optimum mechanical performance.The displacement-load curves and fracture mechanism were analyzed.

  17. Drilling of Hybrid Titanium Composite Laminate (HTCL with Electrical Discharge Machining

    Directory of Open Access Journals (Sweden)

    M. Ramulu

    2016-09-01

    Full Text Available An experimental investigation was conducted to determine the application of die sinker electrical discharge machining (EDM as it applies to a hybrid titanium thermoplastic composite laminate material. Holes were drilled using a die sinker EDM. The effects of peak current, pulse time, and percent on-time on machinability of hybrid titanium composite material were evaluated in terms of material removal rate (MRR, tool wear rate, and cut quality. Experimental models relating each process response to the input parameters were developed and optimum operating conditions with a short cutting time, achieving the highest workpiece MRR, with very little tool wear were determined to occur at a peak current value of 8.60 A, a percent on-time of 36.12%, and a pulse time of 258 microseconds. After observing data acquired from experimentation, it was determined that while use of EDM is possible, for desirable quality it is not fast enough for industrial application.

  18. Absorption properties of radar absorbing structure laminate composites filled with Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Zhengquan Zhang

    2009-12-01

    Full Text Available Radar absorbing structure laminate composites composed of glass fibers, carbon fibers and epoxy resin filled with carbon nanotubes were fabricated. Two optimal double-layer radar absorbing structures were obtained, the smallest reflection loss of them was -19.23 dB and -26.60 dB respectively, and the absorbing bandwidth was 4.2 GHz and 4.0 GHz separately. It was possible to achieve out the reflection loss was smaller than -10 dB in whole 8.2 - 12.4 GHz by adopting double-layered radar absorbing structure, adjusting to the permittivity of the composites and controlling the thickness of each layer materials.

  19. Assessment of FGPM shunt damping for vibration reduction of laminated composite beams

    Science.gov (United States)

    Lezgy-Nazargah, M.; Divandar, S. M.; Vidal, P.; Polit, O.

    2017-02-01

    This work addresses theoretical and finite element investigations of functionally graded piezoelectric materials (FGPMs) for shunted passive vibration damping of laminated composite beams. The properties of piezoelectric patches are assumed to vary through the thickness direction following the exponent or power law distribution in terms of the volume fractions of the constituent materials. By employing Hamilton's principle, the governing differential equations of motion are derived. The resulting system of equations of vibration is solved by employing an efficient three-nodded beam element which is based on a refined sinus piezoelectric model. The effects of effective electromechanical coupling coefficients (EEMCCs), different electric shunt circuits and different material compositions on the shunted damping performance are investigated. The optimal values of the electric components belonging to each shunt circuit are numerically determined.

  20. Gravity Effects of Curing Angle on Laminated Composite Structures: A Review on Novel Study

    Directory of Open Access Journals (Sweden)

    T. T. T. Jennise

    2013-01-01

    Full Text Available Composites manufactured by small and medium industries/entrepreneurs (SMI/E are conventionally cured in the horizontal position. Hence, the confined space restricts optimum productivity. Besides, SMI/E is unable to allocate high budget for high-end technology such as autoclave and vacuum mechanical oven which limits the development of SMI/E as a result of high capital cost. Through a series of literature review, the review confirmed that there is no similar scientific study has been conducted. Consequently, the review is carried out to facilitate the investigation of the feasibility of a gravity cured glass fiber laminated thermosetting composites via vacuum bagging at angle position from horizontal (0° to vertical (90° to enhance the curing space required.

  1. Damage prognosis of adhesively-bonded joints in laminated composite structural components of unmanned aerial vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Farrar, Charles R [Los Alamos National Laboratory; Gobbato, Maurizio [UCSD; Conte, Joel [UCSD; Kosmatke, John [UCSD; Oliver, Joseph A [UCSD

    2009-01-01

    The extensive use of lightweight advanced composite materials in unmanned aerial vehicles (UAVs) drastically increases the sensitivity to both fatigue- and impact-induced damage of their critical structural components (e.g., wings and tail stabilizers) during service life. The spar-to-skin adhesive joints are considered one of the most fatigue sensitive subcomponents of a lightweight UAV composite wing with damage progressively evolving from the wing root. This paper presents a comprehensive probabilistic methodology for predicting the remaining service life of adhesively-bonded joints in laminated composite structural components of UAVs. Non-destructive evaluation techniques and Bayesian inference are used to (i) assess the current state of damage of the system and, (ii) update the probability distribution of the damage extent at various locations. A probabilistic model for future loads and a mechanics-based damage model are then used to stochastically propagate damage through the joint. Combined local (e.g., exceedance of a critical damage size) and global (e.g.. flutter instability) failure criteria are finally used to compute the probability of component failure at future times. The applicability and the partial validation of the proposed methodology are then briefly discussed by analyzing the debonding propagation, along a pre-defined adhesive interface, in a simply supported laminated composite beam with solid rectangular cross section, subjected to a concentrated load applied at mid-span. A specially developed Eliler-Bernoulli beam finite element with interlaminar slip along the damageable interface is used in combination with a cohesive zone model to study the fatigue-induced degradation in the adhesive material. The preliminary numerical results presented are promising for the future validation of the methodology.

  2. Porcelain laminate veneer restorations bonded with a three-liquid silane bonding agent and a dual-activated luting composite.

    Science.gov (United States)

    Matsumura, Hideo; Aida, Yukiko; Ishikawa, Yumi; Tanoue, Naomi

    2006-12-01

    This clinical report describes the fabrication and bonding of porcelain laminate veneer restorations in a patient with anterior open spaces. Laminate veneer restorations made of feldspathic porcelain were etched with 5% hydrofluoric acid, rinsed under tap water, ultrasonically cleaned with methanol, and primed with a chemically activated three-liquid silane bonding agent (Clearfil Porcelain Bond). The enamel surfaces were etched with 40% phosphoric acid, rinsed with water, and primed with a two-liquid bonding agent (Clearfil New Bond) that contained a hydrophobic phosphate (10-methacryloyloxydecyl dihydrogen phosphate; MDP). The restorations were bonded with a dual-activated luting composite (Clapearl DC). The veneers have been functioning satisfactorily for an observation period of one year. Combined use of the Clearfil bonding agents and Clapearl DC luting composite is an alternative to conventional materials for seating porcelain laminate veneer restorations, although the system is inapplicable to dentin bonding.

  3. Application of layered finite elements in the numerical analysis of laminated composite and sandwich structures with delaminations

    Directory of Open Access Journals (Sweden)

    Vuksanović Đorđe

    2015-01-01

    Full Text Available Laminar composites are modern engineering materials widely used in the mechanical and civil engineering. In the paper, some recent advances in a numerical analysis of laminated composite and sandwich plates and shells of different shapes, with existing zones of partial delamination, are presented. The layered finite elements, based on the extended version of the Generalized Laminated Plate Theory of Reddy, are applied for the numerical solution of several structural problems. After the verification of the proposed model for intact structures using the existing data from the literature, the effects of the size and the position of embedded delamination zones on the structural response of laminated structures are investigated numerically by means of a variety of numerical applications.

  4. Influence of stacking sequence on scattering characteristics of the fundamental anti-symmetric Lamb wave at through holes in composite laminates.

    Science.gov (United States)

    Veidt, Martin; Ng, Ching-Tai

    2011-03-01

    This paper investigates the scattering characteristics of the fundamental anti-symmetric (A(0)) Lamb wave at through holes in composite laminates. Three-dimensional (3D) finite element (FE) simulations and experimental measurements are used to study the physical phenomenon. Unidirectional, bidirectional, and quasi-isotropic composite laminates are considered in the study. The influence of different hole diameter to wavelength aspect ratios and different stacking sequences on wave scattering characteristics are investigated. The results show that amplitudes and directivity distribution of the scattered Lamb wave depend on these parameters. In the case of quasi-isotropic composite laminates, the scattering directivity patterns are dominated by the fiber orientation of the outer layers and are quite different for composite laminates with the same number of laminae but different stacking sequence. The study provides improved physical insight into the scattering phenomena at through holes in composite laminates, which is essential to develop, validate, and optimize guided wave damage detection and characterization techniques.

  5. Interfacial Microstructure and Mechanical Properties of Al Alloy/Mg Alloy Laminated Composite Plates Fabricated by Equal Channel Angular Processing

    Institute of Scientific and Technical Information of China (English)

    LI Guorui; ZHAO Dong; ZHAO Yaojiang; ZHOU Bin; WANG Hongxia

    2016-01-01

    KAl (7075) alloy /Mg (AZ31) alloy laminated composite plates were successfully fabricated by the equal channel angular processing (ECAP) by using route A for 1, 2, and 3 passes at 573 K, respectively. After fabrication, the 1-pass ECAPed laminated composite plates were annealed at different temperatures. The microstructure evolution, phase constituent, and bonding strength near the joining interface of Al (7075) alloy /Mg (AZ31) alloy laminated composites plates were evaluated with scanning electron microscopy, X-ray diffraction, and shear tests. The experimental results indicated that a 20 μm diffusion layer was observed at the joining interface of Al (7075) alloy /Mg (AZ31) alloy laminated composites plates fabricated by the 1-pass ECAP, which mainly included Al3Mg2 and Mg17Al12 phases. With the increase of passes, the increase of diffusion layer thickness was not obvious and the form of crack in these processes led to the decrease of bonding strength. For 1-pass ECAPed composites, the thickness of diffusion layer remained unchanged after annealed at 473 K, while the bonding strength reached its maximum value 29.12 MPa. However, after elevating heat treatment temperature to 573 K, the thickness of diffusion layer increased rapidly, and thus the bonding strength decreased.

  6. Lamination of microfibrous PLGA fabric by electrospinning a layer of collagen-hydroxyapatite composite nanofibers for bone tissue engineering.

    Science.gov (United States)

    Kwon, Gi-Wan; Gupta, Kailash Chandra; Jung, Kyung-Hye; Kang, Inn-Kyu

    2017-01-01

    To mimic the muscle inspired cells adhesion through proteins secretion, the lamination of collagen-hydroxyapatite nanorod (nHA) composite nanofibers has been carried out successfully on polydopamine (PDA)-coated microfibrous polylactide-co-glycolide (PLGA) fabrics. The lamination of collagen-hydroxyapatite composite nanofibers on polydopamine-coated microfibrous PLGA fabrics was carried through electrospinning the solution of collagen containing L-glutamic acid-grafted hydroxyapatite nanorods (nHA-GA) at a flow rate of 1.5 mL/h and an applied voltage of 15 kV. In comparison to pristine PLGA, dopamine-coated PLGA and collagen-hydroxyapatite composite nanofiber lamination has produced more wettable surfaces and surface wettability is found to higher with dopamine-coated PLGA fabrics then pristine PLGA. The SEM micrographs have clearly indicated that the lamination of polydopamine-coated PLGA fabric with collagen-hydroxyapatite composite nanofibers has shown increased adhesion of MC3T3E1 cells in comparison to pristine PLGA fabrics. The results of these studies have clearly demonstrated that collagen-nHA composites fibers may be used to create bioactive 3D scaffolds using PLGA as an architectural support agent.

  7. Flutter and thermal buckling control for composite laminated panels in supersonic flow

    Science.gov (United States)

    Li, Feng-Ming; Song, Zhi-Guang

    2013-10-01

    Aerothermoelastic analysis for composite laminated panels in supersonic flow is carried out. The flutter and thermal buckling control for the panels are also investigated. In the modeling for the equation of motion, the influences of in-plane thermal load on the transverse bending deflection are taken into account, and the unsteady aerodynamic pressure in supersonic flow is evaluated by the linear piston theory. The governing equation of the structural system is developed applying the Hamilton's principle. In order to study the influences of aerodynamic pressure on the vibration mode shape of the panel, both the assumed mode method (AMM) and the finite element method (FEM) are used to derive the equation of motion. The proportional feedback control method and the linear quadratic regulator (LQR) are used to design the controller. The aeroelastic stability of the structural system is analyzed using the frequency-domain method. The effects of ply angle of the laminated panel on the critical flutter aerodynamic pressure and the critical buckling temperature change are researched. The flutter and thermal buckling control effects using the proportional feedback control and the LQR are compared. An effective method which can suppress the flutter and thermal buckling simultaneously is proposed.

  8. On the detectability of transverse cracks in laminated composites using electrical potential change measurements

    KAUST Repository

    Selvakumaran, Lakshmi

    2015-03-01

    Real-time health monitoring of structures made of laminated composites is necessary as significant damage may occur without any visible signs on the surface. Inspection by electrical tomography (ET) seems a viable approach that relies on voltage measurements from a network of electrodes across the inspected domain to infer conductivity change within the bulk material. If conductivity decreases significantly with increasing damage, the obtained conductivity map can be correlated to the degradation state of the material. We focus here on detection of transverse cracks. As transverse cracks modify the in-plane transverse conductivity of a single ply, we expect them to be detectable by electrical measurements. Yet, the quality of detection is directly related to the sensitivity of the measurements to the presence of cracks. We use numerical experiments to demonstrate that the sensitivity depends on several material and geometrical parameters. Based on the results, the applicability of ET to detect transverse cracks is discussed. One conclusion from the study is that detecting transverse cracks using ET is more reliable in some laminate configurations than in others. Recommendations about the properties of either the pristine material or the inspected structures are provided to establish if ET is reliable in detecting transverse cracks.

  9. Microstructural Evolution and Fracture Behavior of Friction-Stir-Welded Al-Cu Laminated Composites

    Science.gov (United States)

    Beygi, R.; Kazeminezhad, Mohsen; Kokabi, A. H.

    2014-01-01

    In this study, we attempt to characterize the microstructural evolution during friction stir butt welding of Al-Cu-laminated composites and its effect on the fracture behavior of the joint. Emphasis is on the material flow and particle distribution in the stir zone. For this purpose, optical microscopy and scanning electron microscopy (SEM) images, energy-dispersive spectroscopy EDS and XRD analyses, hardness measurements, and tensile tests are carried out on the joints. It is shown that intermetallic compounds exist in lamellas of banding structure formed in the advancing side of the welds. In samples welded from the Cu side, the banding structure in the advancing side and the hook formation in the retreating side determine the fracture behavior of the joint. In samples welded from the Al side, a defect is formed in the advancing side of the weld, which is attributed to insufficient material flow. It is concluded that the contact surface of the laminate (Al or Cu) with the shoulder of the FSW tool influences the material flow and microstructure of welds.

  10. Effect of phase asynchronism on the fatigue resistance of laminated fiber composites in a plane stress state

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Ya.A.; Limonov, V.A.; Tamuzh, V.P.

    1992-03-01

    The introduction of composite materials in different regions of technology to create load-bearing structural elements working under fatigue loads is making it necessary to study the effect of different structural, service, and other factors on the fatigue resistance of these materials. For example, other authors experimentally studied structural features of laminated composites. Specifically, they studied the way in which fatigue resistance is affected by the angles of orientation and sequence of the layers of a unidirectional organic-fiber-reinforced plastic through the thickness of the laminated packet. Elsewhere, an experimental study was made of unidirectional and laminated composites to determine the effect on fatigue resistance of such service factors as combined simple cyclic loading, loading frequency, ambient temperature, humidity, and asymmetry of the loading cycle. Considering the variety of laminated fiber composites being developed in addition to those that already exist and taking into account the wide range of corresponding service characteristics, it become clear that the fatigue resistance of these materials cannot be evaluated by experimental methods alone. Even for one specific composite, such empirical evaluation requires significant amounts of time. Previous authors proposed and thoroughly tested a theoretical model of the endurance of composite laminates. This method can be used in conjunction with available test results to develop a reliable empirical-theoretical method of calculating the fatigue resistance of composites that will account for the main structural and service characteristics of the material. However, their results are for simple loading, while under actual conditions, with a multiaxial stress state, loading is nonproportional, i.e. it occurs over a complex path. The simplest of nonproportional loading is encountered with asynchronous load application.

  11. Frequency response of laminated composite plates and shells with matrix cracks type of damage mode

    Science.gov (United States)

    Emam, Aly A.

    The present study has been designed to tackle a new set of problems for structural composites, as these materials are finding new applications in civil engineering field. An attempt has been made to study the frequency response of laminated polymer composite plates and shallow shells containing matrix cracks type of damage with arbitrary support conditions and free vibratory motions. The shell governing equations are derived using a simplified shallow shell theory based on a first order shear deformation field. The continuum damage mechanics approach has been used to model the matrix cracks in a damaged region within the plates and shallow shells. In such approach, the damage is accounted for in the laminate constitutive equations by using a set of second order tensor internal state variables which are strain-like quantities. The simplified damage model was then used to study the changes in frequency response of laminated composite plates and shallow cylindrical shells. The Ritz method and a finite element method have been proposed and developed as approximate solution procedures to quantify the change in the free vibration frequencies due to matrix cracks type of damage under both material as well as geometrical variables such as size, shape and extent of damage, degree of curvature, ratio of orthotropy, thickness ratio as well as support conditions. The analysis of various plates and shells with a centrally located damaged-zone depicts a typical trend of reduction in the vibration frequencies. This reduction is more pronounced for higher frequency modes and it shows greater sensitivity toward the size of the damaged region and density of cracks. The results also show that the changes in the frequency, especially for the fundamental mode, appear to be less sensitive to the shell boundary conditions as well as small values of curvature. The investigation of various undamaged plates and shallow shells demonstrates the importance of a first-order shear deformation

  12. Utilization of the Generalized Method of Cells to Analyze the Deformation Response of Laminated Ceramic Matrix Composites

    Science.gov (United States)

    Goldberg, Robert K.

    2012-01-01

    In order to practically utilize ceramic matrix composites in aircraft engine components, robust analysis tools are required that can simulate the material response in a computationally efficient manner. The MAC/GMC software developed at NASA Glenn Research Center, based on the Generalized Method of Cells micromechanics method, has the potential to meet this need. Utilizing MAC/GMC, the effective stiffness properties, proportional limit stress and ultimate strength can be predicted based on the properties and response of the individual constituents. In this paper, the effective stiffness and strength properties for a representative laminated ceramic matrix composite with a large diameter fiber are predicted for a variety of fiber orientation angles and laminate orientations. As part of the analytical study, methods to determine the in-situ stiffness and strength properties of the constituents required to appropriately simulate the effective composite response are developed. The stiffness properties of the representative composite have been adequately predicted for all of the fiber orientations and laminate configurations examined in this study. The proportional limit stresses and strains and ultimate stresses and strains were predicted with varying levels of accuracy, depending on the laminate orientation. However, for the cases where the predictions did not have the desired level of accuracy, the specific issues related to the micromechanics theory were identified which could lead to difficulties that were encountered that could be addressed in future work.

  13. Detection of Fiber Layer-Up Lamination Order of CFRP Composite Using Thermal-Wave Radar Imaging

    Science.gov (United States)

    Wang, Fei; Liu, Junyan; Liu, Yang; Wang, Yang; Gong, Jinlong

    2016-09-01

    In this paper, thermal-wave radar imaging (TWRI) is used as a nondestructive inspection method to evaluate carbon-fiber-reinforced-polymer (CFRP) composite. An inverse methodology that combines TWRI with numerical optimization technique is proposed to determine the fiber layer-up lamination sequences of anisotropic CFRP composite. A 7-layer CFRP laminate [0°/45°/90°/0°]_{{s}} is heated by a chirp-modulated Gaussian laser beam, and then finite element method (FEM) is employed to calculate the temperature field of CFRP laminates. The phase based on lock-in correlation between reference chirp signal and the thermal-wave signal is performed to obtain the phase image of TWRI, and the least square method is applied to reconstruct the cost function that minimizes the square of the difference between the phase of TWRI inspection and numerical calculation. A hybrid algorithm that combines the simulation annealing with Nelder-Mead simplex research method is employed to solve the reconstructed cost function and find the global optimal solution of the layer-up sequences of CFRP composite. The result shows the feasibility of estimating the fiber layer-up lamination sequences of CFRP composite with optimal discrete and constraint conditions.

  14. A shear deformable theory of laminated composite shallow shell-type panels and their response analysis. II - Static response

    Science.gov (United States)

    Khdeir, A. A.; Librescu, L.; Frederick, D.

    1989-01-01

    In the second part of this paper, by using the static counterparts of the governing equations derived in Librescu (1989), the static response of shallow composite shell-type panels subjected to a sinusoidal transverse load is investigated. The numerical applications, encompassing a large number of boundary conditions and various lamination schemes, allow one to obtain some conclusions which are formulated in the paper.

  15. Deformation behavior of an electrodeposited nano-Ni/amorphous Fe78Si9B13 laminated composite sheet

    Directory of Open Access Journals (Sweden)

    Zhang Kaifeng

    2015-01-01

    Full Text Available A nano-Ni/amorphous Fe78Si9B13 composite sheet was prepared in the form of three-ply (Ni-Fe78Si9B13-Ni laminated structure by an electrodeposition method. The average grain size of Ni layers is about 50 nm. The interface of laminated composite was investigated with SEM equipped with energy dispersive scanning (EDS and line analysis technique. The laminated composite has a good interfacial bonding between amorphous layer and nano-Ni layers due to the mutual diffusion of atoms in Fe78Si9B13 and Ni layers during the process of electrodeposition. A maximum elongation of 115.5% was obtained when the volume fraction of nano-Ni layers (VNi was 0.77, which is greatly higher than that of monolithic amorphous Fe78Si9B13 ribbon (36.3% tested under the same conditions. Bulging tests were carried out to evaluate plastic forming properties of the Fe78Si9B13/Ni laminated composite. Under the condition of 450 °C, 4.0 MPa and 30 min, a good bulging part with the relative bulging height (RBH of 0.4 was obtained.

  16. Buckling-driven delamination growth in composite laminates: Guidelines for assessing the threat posed by interlaminar matrix delamination

    DEFF Research Database (Denmark)

    Bhushan, Karihaloo; Stang, Henrik

    2008-01-01

    This paper is concerned with development of a simple procedure to assess the threat posed by interlaminar matrix delaminations to the integrity of composite laminates when they are situated in a compressive stress field. Depending upon the size of the delamination, its location below the surface...

  17. Numerical simulating and experimental study on the woven carbon fiber-reinforced composite laminates under low-velocity impact

    Science.gov (United States)

    Liu, Hanyang; Tang, Zhanwen; Pan, Lingying; Zhao, Weidong; Sun, Baogang; Jiang, Wenge

    2016-05-01

    Impact damage has been identified as a critical form of the defects that constantly threatened the reliability of composite structures, such as those used in the aerospace structures and systems. Low energy impacts can introduce barely visible damage and cause the degradation of structural stiffness, furthermore, the flaws caused by low-velocity impact are so dangerous that they can give rise to the further extended delaminations. In order to improve the reliability and load carrying capacity of composite laminates under low-velocity impact, in this paper, the numerical simulatings and experimental studies on the woven fiber-reinforced composite laminates under low-velocity impact with impact energy 16.7J were discussed. The low velocity impact experiment was carried out through drop-weight system as the reason of inertia effect. A numerical progressive damage model was provided, in which the damages of fiber, matrix and interlamina were considered by VUMT subroutine in ABAQUS, to determine the damage modes. The Hashin failure criteria were improved to cover the failure modes of fiber failure in the directions of warp/weft and delaminations. The results of Finite Element Analysis (FEA) were compared with the experimental results of nondestructive examination including the results of ultrasonic C-scan, cross-section stereomicroscope and contact force - time history curves. It is found that the response of laminates under low-velocity impact could be divided into stages with different damage. Before the max-deformation of the laminates occurring, the matrix cracking, fiber breakage and delaminations were simulated during the impactor dropping. During the releasing and rebounding period, matrix cracking and delaminations areas kept increasing in the laminates because of the stress releasing of laminates. Finally, the simulating results showed the good agreements with the results of experiment.

  18. ESL Based Cylindrical Shell Elements with Hierarchical Shape Functions for Laminated Composite Shells

    Directory of Open Access Journals (Sweden)

    Jae S. Ahn

    2015-01-01

    Full Text Available We introduce higher-order cylindrical shell element based on ESL (equivalent single-layer theory for the analysis of laminated composite shells. The proposed elements are formulated by the dimensional reduction technique from three-dimensional solid to two-dimensional cylindrical surface with plane stress assumption. It allows the first-order shear deformation and considers anisotropic materials due to fiber orientation. The element displacement approximation is established by the integrals of Legendre polynomials with hierarchical concept to ensure the C0-continuity at the interface between adjacent elements as well as C1-continuity at the interface between adjacent layers. For geometry mapping, cylindrical coordinate is adopted to implement the exact mapping of curved shell configuration with a constant curvature with respect to any direction in the plane. The verification and characteristics of the proposed element are investigated through the analyses of three cylindrical shell problems with different shapes, loadings, and boundary conditions.

  19. Electrical resistance load effect on magnetoelectric coupling of magnetostrictive/piezoelectric laminated composite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yaojin, E-mail: wangyaojin@hotmail.co [Key Laboratory of Inorganic Functional Material and Device, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Xiangyong [Key Laboratory of Inorganic Functional Material and Device, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China); Jiao, Jie; Liu, Linhua [Key Laboratory of Inorganic Functional Material and Device, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Di, Wenning; Luo, Haosu [Key Laboratory of Inorganic Functional Material and Device, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China); Or, Siu Wing, E-mail: eeswor@polyu.edu.h [Department of Electrical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)

    2010-06-25

    The effect of electrical resistance load on the magnetoelectric (ME) coupling of laminated composite of Tb{sub 0.3}Dy{sub 0.7}Fe{sub 1.92} (Terfenol-D) magnetostrictive alloy and 0.7Pb (Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.3PbTiO{sub 3} (PMN-PT) piezoelectric single crystal is investigated at both non-resonance and resonance frequencies. The results show that (i) the ME coefficient and ME resonance frequency increase with the increase in electrical resistance load, and (ii) the maximum ME power occurs in open-circuit condition. The present study provides the basis for the design of ME sensors and their signal-processing and electronic circuits.

  20. Free material stiffness design of laminated composite structures using commercial finite element analysis codes

    DEFF Research Database (Denmark)

    Henrichsen, Søren Randrup; Lindgaard, Esben; Lund, Erik

    2015-01-01

    In this work optimum stiffness design of laminated composite structures is performed using the commercially available programs ANSYS and MATLAB. Within these programs a Free Material Optimization algorithm is implemented based on an optimality condition and a heuristic update scheme. The heuristic...... update scheme is needed because commercially available finite element analysis software is used. When using a commercial finite element analysis code it is not straight forward to implement a computationally efficient gradient based optimization algorithm. Examples considered in this work are a clamped......-clamped 2D plate loaded in two load cases and a point loaded six layered 3D double curved corner hinged shell. The first example displays the effect of varying the size of patches having the same parametrization, and the second illustrates the benefit of using a layered free material parametrization...

  1. Special hybrid stress element for stress analyses around circular cutouts in laminated composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A 3-dimensional hybrid stress element with a traction-free cylindrical surface based on amodified complementary energy principle has been derived for efficient and accurate analysis of stressconcentration around circular cutouts in thin to thick laminated composites. New expressions of sixstress components are developed by using three stress-functions in cylindrical co-ordinates, so that thehomogeneous equilibrium equations, the interlayer surface transverse-stresses and the traction-freeboundary condition on the cylindrical surface are satisfied exactly, while the interelement traction conti-nuity has been relaxed via the Lagrange multiplier method. Transverse-shear deformation effects areincorporated in each layer with displacement continuity enforced along interlayer surface. Selected ex-amples are used to demonstrate the efficiency and accuracy of the present special element.

  2. Effect of Impact Damage and Open Hole on Compressive Strength of Hybrid Composite Laminates

    Science.gov (United States)

    Hiel, Clement; Brinson, H. F.

    1993-01-01

    Impact damage tolerance is a frequently listed design requirement for composites hardware. The effect of impact damage and open hole size on laminate compressive strength was studied on sandwich beam specimens which combine CFRP-GFRP hybrid skins and a syntactic foam core. Three test specimen configurations have been investigated for this study. The first two were sandwich beams which were loaded in pure bending (by four point flexure). One series had a skin damaged by impact, and the second series had a circular hole machined through one of the skins. The reduction of compressive strength with increasing damage (hole) size was compared. Additionally a third series of uniaxially loaded open hole compression coupons were tested to generate baseline data for comparison with both series of sandwich beams.

  3. Buckling of laminated composite plates subjected to mechanical and thermal loads using meshless collocations

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Sandeep; Shukla, K. K. [Motilal Nehru National Institute of Technology, Allahabad (India); Shingh, Jeeoot [Department of Mechanical Engineering, Birla Institute of Technology Mesra, Ranchi (India)

    2013-02-15

    Meshless collocations utilizing Gaussian and Multi quadric radial basis functions for the stability analysis of orthotropic and cross ply laminated composite plates subjected to thermal and mechanical loading are presented. The governing differential equations of plate are based on higher order shear deformation theory considering two different transverse shear stress functions. The plate governing differential equations are discretized using radial basis functions to cast a set of simultaneous equations. The convergence of both radial basis functions is studied for different values of shape parameters. Several numerical examples are undertaken to demonstrate the accuracy of present method and the effects of orthotropy ratio of the material, span to thickness ratio of the plate, and fiber orientation on critical load/temperature are also presented.

  4. Evaluation of interlaminar shear strength of a unidirectional carbon/epoxy laminated composite under impact loading

    Science.gov (United States)

    Yokoyama, T.; Nakai, K.

    2006-08-01

    The interlaminar shear strength (ILSS) of a unidirectional carbon/epoxy (T700/2521) laminated composite under impact loading is determined using the conventional split Hopkinson pressure bar. Double-notch shear (DNS) specimens with lateral constraint from a supporting jig are used in the static and impact interlaminar compressive shear tests. Short-beam shear specimens are also used under static 3-point bending. Numerical stress analyses are performed to determine the shear stress and normal stress distributions on the expected failure plane in the DNS specimen using the MSC/NASTRAN package. The effect of deformation rate on the ILSS and failure mode is investigated. It is observed that the ILSS is independent of the deformation rate up to nearly 1.5m/s (dotγ ≈ 780/s). The validity of the test results is confirmed by microscopic examinations of both static and impact failure surfaces for the DNS specimens.

  5. Micromechanisms in tension-compression fatigue of composite laminates containing transverse plies

    DEFF Research Database (Denmark)

    Gamstedt, E.K.; Sjögren, B.A.

    1999-01-01

    was subjected to a compressive load. Since debond propagation is more susceptible to mode I loading, the sensitivity to tension-compression fatigue is explained by the effective crack-tip opening in compressive loading for sufficiently large debond cracks. This has also been verified by finite-element analysis......For both monotonic and fatigue loading conditions, debonding is the subcritical micromechanism which leads to transverse cracking and ultimately influences final failure of the composite structure. Previous studies show that tension-compression fatigue is more detrimental than tension......-tension fatigue to transverse and multidirectional laminates. By analysing the debonding mechanisms and modelling thereof, the macroscopic fatigue behaviour can be better understood. Also, the dominant crack-propagation mode can be identified which may be of use in selection of constituent material properties...

  6. Optical Evaluation on Delamination Buckling of Composite Laminate with Impact Damage

    Directory of Open Access Journals (Sweden)

    J. T. Ruan

    2014-01-01

    Full Text Available The delamination buckling and growth behaviors of a cross-ply composite laminate with damage induced by low velocity impact are investigated optically using three-dimensional digital image correlation (3D-DIC method. For the 3D deformation measurement, the 3D-DIC setup comprised of two CCD cameras was adopted. The rectangle specimen was impacted under the impact energy of 7.0 J using a drop-weight testing machine, and the impact damage was detected by means of X-ray nondestructive evaluation (NDE technique. The 3D deformation field measured with the optical system clearly reveals that the delamination buckling characteristic of the specimen mainly appears local deformation mode under compression after impact test. Moreover, the behavior of delamination growth evaluated by the 3D-DIC optical method reasonably agrees with the NDE observed damage result after compression.

  7. The thermo-optical behavior of turbid composite laminates under highly energetic laser irradiations

    Science.gov (United States)

    Allheily, Vadim; Merlat, Lionel; Lacroix, Fabrice; Eichhorn, Alfred; L'Hostis, Gildas

    2017-01-01

    From their prior emergence in the military domain but also nowadays in the civilian area, unmanned air vehicles constitute a growing threat to the todays civilization. In this respect, novel laser weapons are considered to eradicate this menace and the vulnerability of typical aeronautic materials under 1.07μm-wavelength irradiations is also investigated. In this paper, Kubelka-Munk optical parameters of laminated glass fiber-reinforced plastic composites are first assessed to build up a basic analytical interaction model involving internal refraction and reflection as well as the scattering effect due to the presence of glass fibers. Moreover, a thermo-gravimetric analysis is carried out and the kinetic parameters of the decomposition reaction extracted from this test with the Friedman method are verified trough a comparison with experimental measurements.

  8. Failure of Laminated Composites at Thickness Discontinuities: An Experimental and Analytical Study

    Science.gov (United States)

    Lee, Sangwook; Knauss, Wolfgang

    1998-01-01

    Failure initiation of laminated composites at a thickness discontinuity is studied experimentally with the aid of an optical microscope under combined loading of tension, transverse shear and bending, making use of three- and four-point bending arrangements. Because transverse shear produced relatively small effects in failure initiation results are presented as tension-bending interactions. Two loading frames for three- and four-point bending were designed to apply moment and tension simultaneously to produce failure by generating a ply crack; this initiation was evaluated by finite element analysis using ABAQUS. For cross-plies bounding the interface at the base of the step it is found that a maximum strain criterion applied to the continuing (long) ply describes the failure initiation. Ultimate failure resulted at loads on the order of 25 to 35% higher than those at failure initiation.

  9. Free Vibration Analysis of a Cross-Ply Laminated Composite Beam on Pasternak Foundation

    Directory of Open Access Journals (Sweden)

    R. A. Jafari-Talookolaei

    2007-01-01

    Full Text Available In this study, free vibration analysis of a cross-ply laminated composite beam (LCB on Pasternak foundation was investigated. Natural frequencies of beam on Pasternak foundation are computed using finite element method (FEM on the basis of Timoshenko beam theory. Effect of both shear deformation and rotary inertia are implemented in the modeling of stiffness and mass matrices. The model was designed in such a way that it can be used for single-stepped cross-section, stepped foundation and multi-span beams. Results of few examples are compared with finding in literature and good agreements were achieved. Natural frequencies of LCBs with different layers arrangements (symmetric and non-symmetric are compared. For multi-span beam, variation of frequency with respect to number of spans was also studied.

  10. Towards mechanisms-guided resistivity-based monitoring of damage evolution in laminated composites

    KAUST Repository

    Lubineau, Gilles

    2013-04-05

    A convenient health monitoring technique for detecting degradation in laminated composite is to monitor the change of electrical resistance along multiple conduction paths within the structure. Yet, the relations between the global modification of resistivity and the exact underlying damage map is still unclear that makes diffcult to interpret these nondestructive-testing results. The challenge is then to be able to reconstruct from these global observation the underlying damage map. This is even more diffcult due to the numerous underlying damage mechanisms that can take place either at the inter laminar of intra laminar level. This paper intends to provide some preliminary insights about strategies to recover the damage state based only on global measurements. We focus here on transverse cracking detection. We introduce the homogenization process that defines at the meso scale an equivalent homogeneous ply that is energetically equivalent to the cracked one. This can be used as a first tool to reconstruct damage maps based on global resistivity measurements.

  11. Electrical impedance spectroscopy for measuring the impedance response of carbon-fiber-reinforced polymer composite laminates

    KAUST Repository

    Almuhammadi, Khaled

    2017-02-16

    Techniques that monitor the change in the electrical properties of materials are promising for both non-destructive testing and structural health monitoring of carbon-fiber-reinforced polymers (CFRPs). However, achieving reliable monitoring using these techniques requires an in-depth understanding of the impedance response of these materials when subjected to an alternating electrical excitation, information that is only partially available in the literature. In this work, we investigate the electrical impedance spectroscopy response at various frequencies of laminates chosen to be representative of classical layups employed in composite structures. We clarify the relationship between the frequency of the electrical current, the conductivity of the surface ply and the probing depth for different CFRP configurations for more efficient electrical signal-based inspections. We also investigate the effect of the amplitude of the input signal.

  12. Effect of Grinding Process Parameters on Surface Area Roughness of Glass fibre Reinforced Composite Laminate under Dry and Coolant Environment

    Directory of Open Access Journals (Sweden)

    P. Chockalingam

    2016-04-01

    Full Text Available This paper presents a comparative study on dry and wet grinding of chopped strand mat glass fibre reinforced polymer laminates using an alumina wheel. Investigations were performed to study the impact of the grinding parameters, namely feed, speed, and depth of cut on grinding force ratio and surface area roughness. Effective grinding parameters were sought in this study to maximize grinding force ratio and minimize surface area roughness. Test results show that coolant helped to decrease surface area roughness, but inevitably reduced the grinding force ratio in some cases. These findings lead to economic machining solution for optimum grinding conditions in grinding composite laminates.

  13. ULTRASONIC INFLUENCE OF POROSITY LEVEL ON CFRP COMPOSITE LAMINATES USING RAYLEIGH PROBE WAVES

    Institute of Scientific and Technical Information of China (English)

    Je-Woong Park; Do-Jung Kim; Kwang-Hee Im; Sang-Kyu Park; David K.Hsu; Adam H.Kite; Sun-Kyu Kim; Kil-Sung Lee; In-Young Yang

    2008-01-01

    It was found that a pitch-catch signal was more sensitive than normal incidence backwall echo of longitudinal wave to subtle flaw conditions in the composites (damages,fiber orientation,low level porosity,ply waviness,and cracks).Both the strength and stiffness depend on the fiber orientation and porosity volume in the composites.The porosity content of a composite structure is critical to the strength and performance of the structure in general.The depth of the sampling volume where the pitch-catch signal came from was relatively shallow with the head to-head miniature Rayleigh probes,but the depth can be increased by increasing the separation distance of the transmitting and receiving probes.Also,a method was utilized to determine the porosity content of a composite lay-up by processing micrograph images of the laminate.A free software package was utilized to process micrograph images of the test sample.The results from the image processing method were compared with existing data.Beam profile was characterized in unidirectional CFRP(carbon fiber reinforced plastics) using pitch-catch Rayleigh probes and the one-sided pitch-catch technique was utilized to produce C-scan images with the aid of the automatic scanner.

  14. Crack Growth Mechanisms under Anti-Plane Shear in Composite Laminates

    Science.gov (United States)

    Horner, Allison Lynne

    The research conducted for this dissertation focuses on determining the mechanisms associated with crack growth in polymer matrix composite laminates subjected to anti-plane shear (mode III) loading. For mode III split-beam test methods were proposed, and initial evaluations were conducted. A single test method was selected for further evaluation. Using this test method, it was determined that the apparent mode III delamination toughness, GIIIc , depended on geometry, which indicated a true material property was not being measured. Transverse sectioning and optical microscopy revealed an array of transverse matrix cracks, or echelon cracks, oriented at approximately 45° and intersecting the plane of the delamination. Subsequent investigations found the echelon array formed prior to the onset of planar delamination advance and that growth of the planar delamination is always coupled to echelon array formation in these specimens. The evolution of the fracture surfaces formed by the echelon array and planar delamination were studied, and it was found that the development was similar to crack growth in homogenous materials subjected to mode III or mixed mode I-III loading, although the composite laminate architecture constrained the fracture surface development differently than homogenous materials. It was also found that, for split-beam specimens such as those used herein, applying an anti-plane shear load results in twisting of the specimen's uncracked region which gives rise to a mixed-mode I-III load condition. This twisting has been related to the apparent mode III toughness as well as the orientation of the transverse matrix cracks. A finite element model was then developed to study the mechanisms of initial echelon array formation. From this, it is shown that an echelon array will develop, but will become self-limiting prior to the onset of planar delamination growth.

  15. Effect of static and cyclic loading on ceramic laminate veneers adhered to teeth with and without aged composite restorations.

    Science.gov (United States)

    Gresnigt, Marco M; Ozcan, Mutlu; Kalk, Warner; Galhano, Graziela

    2011-12-01

    Existing composite restorations on teeth are often remade prior to the cementation of fixed dental prostheses. The aim of this study was to evaluate the effect of static and cyclic loading on ceramic laminate veneers adhered to aged resin composite restorations. Eighty sound maxillary incisors were collected and randomly divided into four groups: group 1: control group, no restorations; group 2: two Class III restorations; group 3: two Class IV restorations; group 4: complete composite substrate. Standard composite restorations were made using a microhybrid resin composite (Anterior Shine). Restored teeth were subjected to thermocycling (6000 cycles). Window preparations were made on the labial surface of the teeth for ceramic laminate fabrication (Empress II). Teeth were conditioned using an etch-and-rinse system. Existing composite restorations representing the aged composites were silica coated (CoJet) and silanized (ESPE-Sil). Ceramic laminates were cemented using a bis-GMA-based cement (Variolink Veneer). The specimens were randomly divided into two groups and were subjected to either static (groups 1a, 2a, 3a, 4a) or cyclic loading (groups 1b, 2b, 3b, 4b). Failure type and location after loading were classified. Data were analyzed using one-way ANOVA and Tukey's test. Significantly higher fracture strength was obtained in group 4 (330 ± 81 N) compared to the controls in group 1 (179 ± 120 N) (one-way ANOVA, p ceramic were seen. Ceramic laminate veneers bonded to conditioned aged composite restorations provided favorable results. Surface conditioning of existing restorations may eliminate the necessity of removing aged composite restorations.

  16. FEM buckling analysis of quasi-isotropic symmetrically laminated rectangular composite plates with a square/rectangular cutout

    Energy Technology Data Exchange (ETDEWEB)

    Narayana, A. Lakshmi [Hindustan Aeronautics Limited, Bangalore (India); Rao, Krishnamohana [JNTUH, Hyderabad (India); Kumar, R. Vijaya [Hindustan Aeronautics Limited, Bangalor (India)

    2013-05-15

    A numerical study was conducted using the finite element method to determine the effects of square and rectangular cutouts on the buckling behavior of a 16-ply quasi-isotropic graphite/epoxy symmetrically laminated rectangular composite plate. The square/ rectangular cutouts were subjected to uniaxial compression loading. This study addresses the effects of the size of the square/rectangular cutout, orientation of the square/rectangular cutout, plate aspect ratio (a/b), and plate length/thickness ratio (a/t) on the buckling behavior of the symmetrically laminated rectangular composite plate under uniaxial compression loading. Buckling loads were computed for seven different quasi-isotropic laminate configurations [0 .deg. /+45 .deg. /-45 .deg. /90 .deg. ]{sub 2s}, [15 .deg. /+60 .deg. /-30 .deg. /-75 .deg. ]{sub 2s}, [30 .deg. /+75 .deg. /-15 .deg. /-60 .deg. ]{sub 2s}, [45 .deg. /+90 .deg. /0 .deg. /-45 .deg. ]{sub 2s}, [60 .deg. /-75 .deg. /+15 .deg. /-30 .deg. ]{sub 2s}, [75 .deg. /-60 .deg. /+30 .deg. /-15 .deg. ]{sub 2s}, [90 .deg. /-45 .deg. /+45 .deg. / .deg. 0 .deg. ]{sub 2s}. Results showed that the magnitudes of the buckling loads decrease with increasing cutout positioned angle as well as c/b and d/b ratios for plates with a rectangular cutout. The symmetrically laminated quasi-isotropic [0 .deg. /+45 .deg. /-45 .deg. /90 .deg. ]{sub 2s} composite plate is stronger than all other symmetrically analyzed laminated quasi-isotropic composite plates. The magnitudes of the buckling loads of a rectangular composite plate with square/rectangular cutout decrease with increasing plate aspect ratio (a/b) and plate length/thickness (a/t) ratio.

  17. Nonlinear magneto-electric response of a giant magnetostrictive/piezoelectric composite cylinder

    Institute of Scientific and Technical Information of China (English)

    Yuan-Wen Gao; Juan-Juan Zhang

    2012-01-01

    In this study,we investigate the nonlinear coupling magneto-electric (ME) effect of a giant magnetostrictive/piezoelectric composite cylinder.The nonlinear constitutive relations of the ME material are taken into account,and the influences of the nonlinear material properties on the ME effect are investigated for the static and dynamic cases,respectively.The influences of different constraint conditions on the ME effect are discussed.In the dynamic case considering nonlinear material properties,the double frequency ME response (The response frequency is twice the applied magnetic frequency) is obtained and discussed,which can be used to explain the experiment phenomenon in which the input signal with frequency f is converted to the output signal with 2f in ME laminated structures.Some calculations on nonlinear ME effect are conducted.The obtained results indicate that the nonlinear material properties affect not only the magnitude of the ME effect in the static case but also the ME response frequency in the dynamic case.

  18. Experimental Evaluation of Metal Composite Multi Bolt Radial Joint on Laminate Level, under uni Axial Tensile Loading

    Directory of Open Access Journals (Sweden)

    C Sharada Prabhakar

    2017-03-01

    Full Text Available Longitudinal tensile load exerted due to internal hydraulic pressure, on bolted radial joints between large size PAN carbon epoxy filament wound composite cylindrical section and small size 15CDV6 steel cylindrical sections, were simulated and tested on flat laminate level, mainly to check the strength of PAN carbon epoxy helical wound laminate made by wet winding method. Small segmental portion of circumference of cylindrical sections was considered as width of composite laminate and of metallic plates, necessary to accommodate 5 rows of fasteners in transverse direction with specified pitch distance. Bolted radial joints between carbon epoxy helical wound flat laminate and 15CDV6 steel plates were realized with 8 numbers of steel fasteners distributed in 3 longitudinal and 5 transverse rows at each joint. Helical angle of winding, length and thickness of carbon epoxy laminate was ±22.5°, 458mm and 11mm respectively. Length and structural thickness of radial joints, total length and width of assembly test specimen were 98mm, 18mm, 870mm and 169.43mm respectively. Joints were tested under uni-axial tensile load up to failure. Joints failed at 18 tonnes (1.7 times of design load. Failure mode was observed as initiation of bearing failure at all 8, countersink fastener holes in laminate and shear out failure at edge hole. Strains in fibre direction, at 45°and at transverse to fibre direction were found very less. Maximum compressive strain and residual strain, near fastener holes were found as -1423 and -136 micro strain respectively. Test was successful

  19. Experimental verification of a progressive damage model for composite laminates based on continuum damage mechanics. M.S. Thesis Final Report

    Science.gov (United States)

    Coats, Timothy William

    1994-01-01

    Progressive failure is a crucial concern when using laminated composites in structural design. Therefore the ability to model damage and predict the life of laminated composites is vital. The purpose of this research was to experimentally verify the application of the continuum damage model, a progressive failure theory utilizing continuum damage mechanics, to a toughened material system. Damage due to tension-tension fatigue was documented for the IM7/5260 composite laminates. Crack density and delamination surface area were used to calculate matrix cracking and delamination internal state variables, respectively, to predict stiffness loss. A damage dependent finite element code qualitatively predicted trends in transverse matrix cracking, axial splits and local stress-strain distributions for notched quasi-isotropic laminates. The predictions were similar to the experimental data and it was concluded that the continuum damage model provided a good prediction of stiffness loss while qualitatively predicting damage growth in notched laminates.

  20. Evaluation of progressive damage of nano-modified composite laminates under repeated impacts

    Science.gov (United States)

    Koricho, Ermias G.; Karpenko, Oleksii; Khomenko, Anton; Haq, Mahmoodul; Cloud, Gary L.; Udpa, Lalita

    2016-04-01

    However, studies on the effect of nano-reinforcements in repeated impact scenarios are relatively limited. This work investigates the effect of resin nanoclay modification on the impact resistance of glass-fiber reinforced polymer (GFRP) composites subjected to repeated impacts. Three impact energy levels were used in experiments with a minimum of four specimens per case for statistical significance. Each sample was subjected to 40 repeated impacts or was tested up to perforation, whichever happened first. The impact response was evaluated in terms of evolution of the peak force, bending stiffness, visual damage inspection and optical transmission scanning (OTS) at critical stages as a function of number of impacts. Also, the damage degree (DD) was calculated to monitor the evolution of damage in the laminates. As expected, the impact response of the GFRP composites varied based on the presence of nano-clay and the applied impact energy. The modification of the resin with nano-clay introduced novel phenomena that changed the damage progression mechanism under repetitive impacts, which was verified by visual observation and optical transmission scanning. A better understanding of these phenomena (e.g. crack-bridging, tortuosity) and their contributions to enhancements in the impact behavior and modifications of the types of damage propagation can lead to better design of novel structural composites.

  1. Comprehensively simulating the mixed-mode progressive delamination in composite laminates

    Science.gov (United States)

    Gao, Zhenyuan

    Delamination, or interlaminar debonding, is a commonly observed failure mechanism in composite laminates. It is of great significance to comprehensively simulate the mixed-mode progressive delamination in composite structures because by doing this, people can save a lot of effort in evaluating the safe load which a composite structure can endure. The objective of this thesis is to develop a numerical approach to simulating double-cantilever beam (DCB) and mixed-mode bending (MMB) tests and also of specifying/validating various cohesive models. A finite element framework, which consists of properly selecting time integration scheme (explicit dynamic), viscosity, load rate and mass scaling, is developed to yield converged and accurate results. Two illustrative cohesive laws (linear and power-law) are programmed with a user- defined material subroutine for ABAQUS/Explicit, VUMAT, and implemented into the finite element framework. Parameters defined in cohesive laws are studied to evaluate their effects on the predicted load-displacement curves. The finite element model, together with the predetermined model parameters, is found to be capable of producing converged and accurate results. The finite element framework, embedded with the illustrative cohesive laws, is found to be capable of handling various interfacial models. The present approach is concluded to be useful in simulating delamination with more sophisticated material models. Together with the method for determining model parameters, it can be used by computer codes other than ABAQUS.

  2. Fabrication and characterization of Polymer laminate composites reinforced with bi-woven carbon fibers

    Directory of Open Access Journals (Sweden)

    P.V.Sanjeev Kumar

    2015-04-01

    Full Text Available The present paper evaluate slaminatedcarbonbi-wove fibers Reinforced with vinyl ester composites. Vinyl ester was used as a matrix to prepare composites by in situ polymerization technique. Four planar layers were made simultaneously by keeping one over the other and each layer made sure to be weighed off by 15% which was maintained in all layers with different orientations. Pre-assumed Layer-1 is (50/5050%,0º; Layer-2 is (35/35/30 35% 0º, 35% +45º,30%,0;Layer-3is (25/50/25 25% 0º, 50%+45º,25-45º; and Layer-4is (25/25/25/25 (25% 0º, 25% +45º,25% -45º,25% 90º.The composite was prepared with the help of hand layup technique. Test ready specimens were tested with the help of shearing machine in accordance with ASTM Standards .It was observed that vinyl ester made good interface with parent fiber material. Flexural strength and Tensile strength have improved up to 3rd layer and decreased afterwards whereas Flexural modulus and Tensile modulus have linearly increased up to 4th layer. Thermal stability and Glass transition temperature have also been found to be satisfactory for all the laminated layers. Chemical resistance was good for the entire chemicals except sodium hydroxide.

  3. Influence of Compression and Shear on the Strength of Composite Laminates with Z-Pinned Reinforcement

    Science.gov (United States)

    O'Brien, T. Kevin; Krueger, Ronald

    2005-01-01

    The influence of compression and shear loads on the strength of composite laminates with z-pins is evaluated parametrically using a 2D Finite Element Code (FLASH). Meshes were generated for three unique combinations of z-pin diameter and density. A laminated plate theory analysis was performed on several layups to determine the bi-axial stresses in the zero degree plies. These stresses, in turn, were used to determine the magnitude of the relative load steps prescribed in the FLASH analyses. Results indicated that increasing pin density was more detrimental to in-plane compression strength than increasing pin diameter. FLASH results for lamina with z-pins were consistent with the closed form results, and FLASH results without z-pins, if the initial fiber waviness due to z-pin insertion was added to the fiber waviness in the material to yield a total misalignment. Addition of 10% shear to the compression loading significantly reduced the lamina strength compared to pure compression loading. Addition of 50% shear to the compression indicated shear yielding rather than kink band formation as the likely failure mode. Two different stiffener reinforced skin configurations with z-pins, one quasi-isotropic and one orthotropic, were also analyzed. Six unique loading cases ranging from pure compression to compression plus 50% shear were analyzed assuming material fiber waviness misalignment angles of 0, 1, and 2 degrees. Compression strength decreased with increased shear loading for both configurations, with the quasi-isotropic configuration yielding lower strengths than the orthotropic configuration.

  4. In vitro evaluation of the fracture resistance and microleakage of porcelain laminate veneers bonded to teeth with composite fillings after cyclic loading

    OpenAIRE

    Sadighpour, Leyla; Geramipanah, Farideh; Allahyari, Somayeh; Fallahi Sichani, Babak; Kharazi Fard, Mohamd Javad

    2014-01-01

    PURPOSE There is insufficient data regarding the durability of porcelain laminate veneers bonded to existing composite fillings. The aim of the present study was to evaluate the fracture resistance and microleakage of porcelain laminate veneers bonded to teeth with existing composite fillings. MATERIALS AND METHODS Thirty maxillary central incisors were divided into three groups (for each group, n=10): intact teeth (NP), teeth with class III composite fillings (C3) and teeth with class IV cav...

  5. Size effects on the magnetoelectric response on PVDF/Vitrovac 4040 laminate composites

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.P. [Centro/Departamento de Física, Universidade do Minho, 4710-057 Braga (Portugal); Martins, P., E-mail: pmartins@fisica.uminho.pt [Centro/Departamento de Física, Universidade do Minho, 4710-057 Braga (Portugal); INL-International Iberian Nanotechnology Laboratory, 4715-330 Braga (Portugal); Lasheras, A.; Gutiérrez, J.; Barandiarán, J.M. [BCMaterials and Universidad del País Vasco UPV/EHU, Department of Electricity and Electronics, Faculty of Science and Technology, P.O. Box 644, E-48080 Bilbao (Spain); Lanceros-Mendez, S., E-mail: lanceros@fisica.uminho.pt [Centro/Departamento de Física, Universidade do Minho, 4710-057 Braga (Portugal); INL-International Iberian Nanotechnology Laboratory, 4715-330 Braga (Portugal)

    2015-03-01

    Tri-layered and bi-layered magnetoelectric (ME) flexible composite structures of varying geometries and sizes consisting on magnetostrictive Vitrovac and piezoelectric poly(vinylidene fluoride) (PVDF) layers were fabricated by direct bonding. From the ME measurements it was determined that tri-layered composites structures (magnetostrictive–piezoelectric–magnetostrictive type), show a higher ME response (75 V cm{sup −1} Oe{sup −1}) than the bi-layer structure (66 V cm{sup −1} Oe{sup −1}). The ME voltage coefficient decreased with increasing longitudinal size aspect ratio between PVDF and Vitrovac layers (from 1.1 to 4.3), being observed a maximum ME voltage coefficient of 66 V cm{sup −1} Oe{sup −1}. It was also observed that the composite with the lowest transversal aspect ratio between PVDF and Vitrovac layers resulted in better ME performance than the structures with higher transversal size aspect ratios. It was further determined an intimate relation between the Area{sub PVDF}/Area{sub Vitrovac} ratio and the ME response of the composites. When such ratio values approach 1, the ME response is the largest. In addition the ME output value and magnetic field response were controlled by changing the number of Vitrovac layers, which allows the development of magnetic sensors and energy harvesting devices. - Highlights: • Vitrovac/PVDF laminates have been fabricated. • Size and aspect ratio effects on the ME response have been investigated. • Bi-layered and three-layered composites have been investigated • High ME response of 75 V cm{sup −1} Oe{sup −1} has been obtained. • The tailored ME response is suitable for sensor applications.

  6. Thermal effect on dynamics of thin and thick composite laminated microbeams by modified couple stress theory for different boundary conditions

    Science.gov (United States)

    Ghadiri, Majid; Zajkani, Asghar; Akbarizadeh, Mohammad Reza

    2016-12-01

    In this article, thermal effect on free vibration behavior of composite laminated microbeams based on the modified couple stress theory is presented. The proposed anisotropic model is developed by using a variational formulation. The governing equations and boundary conditions are obtained based on a modified couple stress theory and using the principle of minimum potential energy and considering different beam theories, i.e., Euler-Bernoulli, Timoshenko and Reddy beam theories. Unlike the classical beam theories, this model contains a material length scale parameter and can capture the size effect. Free vibration of a simply supported beam is solved by utilizing Fourier series. In addition, the fundamental frequency is achieved by using the generalized differential quadrature method for four types of cross-ply laminations with clamped-clamped, clamped-hinged and hinged-hinged boundary conditions for different beam theories. For investigating different parameters including temperature changes, material length scale parameter, beam thickness, some numerical results on different cross-ply laminated beams are presented. The fundamental frequency of different thin and thick beam theories is investigated by increasing slenderness ratio and thermal loads. The results prove that the modified couple stress theory increases the natural frequency under the thermal effects for free vibration of composite laminated microbeams.

  7. Optical bistability in nonlinear composites with coated ellipsoidal nanoparticles

    CERN Document Server

    Pinchuk, A

    2003-01-01

    Nonlinear composite structures show great promise for use in optical switching, signal processing, etc. We derive an effective nonlinear dielectric permittivity of composite structures where coated ellipsoidal nonlinear particles are imbedded in a linear host medium. The derived expression for the effective dielectric permittivity tensor follows the Clasius-Mossotti approximation. We observe conditions for the existence of the optical bistability effect in a coated ellipsoidal particle with a nonlinear core and a metallic shell. Our numerical results show stronger bistability effects in more dense suspensions of nonlinear heterogeneous ellipsoids.

  8. On the Through-the-Width Multiple Delamination, and Buckling and Postbuckling Behaviors of Symmetric and Unsymmetric Composite Laminates

    Science.gov (United States)

    Liu, P. F.; Zheng, J. Y.

    2013-12-01

    Multiple delamination causes severe degradation of the stiffness and strength of composites. Interactions between multiple delamination, and buckling and postbuckling under compressive loads add the complexity of mechanical properties of composites. In this paper, the buckling, postbuckling and through-the-width multiple delamination of symmetric and unsymmetric composite laminates are studied using 3D FEA, and the virtual crack closure technique with two delamination failure criteria: B-K law and power law is used to predict the delamination growth and to calculate the mixed-mode energy release rate. The compressive load-strain curves, load-central deflection curves and multiple delamination process for eight composite specimens with different initial delamination sizes and their distributions as well as two angle-ply configurations 04//(± θ)6//04 ( θ = 0° and 45°, and "//" denotes the delaminated interface) are comparatively studied. From numerical results, the unsymmetry decreases the local buckling load and initial delamination load, but does not affect the global buckling load compared with the symmetric laminates. Besides, the unsymmetry affects the unstable delamination and buckling behaviors of composite laminates largely when the initial multiple delamination sizes are relatively small.

  9. Impact Analysis of Embedded Delamination Location in Hybrid Curved Laminated Composite Stiffened Panel

    Science.gov (United States)

    Naini, Jeevan Kumar; P, Ramesh Babu

    2016-08-01

    Modern, aero structures are predominantly of curved construction characterized by a skin and stiffeners. The latest generation of large passenger aircraft also uses mostly composite material in their primary structure and there is trend towards the utilization of bonding of subcomponents. The presence of delamination is a major problem in composite laminated panels and so, it is of great concern to both the academic and aeronautical industrial worlds Indeed delamination can strongly affect the material strength and, sometimes, can cause their breaking up in service. A Pre-damaged configuration is loaded to study the delamination location and mode for delamination initiation and propagation. A parametric study is conducted to investigate the effect of the location of the delamination propagation when delamination is embedded inbetween plies of the skin-stiffener interface, with the cases i) delamination located at front and inbetween plies of the skin-stiffener interface ii) delamination located in middle and inbetween plies of the skin-stiffener interface iii) delamination located at the end and inbetween plies of the skin- stiffener interface. Further the influence of the location of the delamination on load carrying capacity of the panel is investigated. The effect of location of debonds on crack growth and collapse behavior is analyzed using analysis tool. An analysis tool is applied that includes an approach for predicting interlaminar damage initiation and interlaminar damage growth as well as in-plane damage mechanisms to predict the design of defect free panel.

  10. A comparative evaluation of in-plane shear test methods for laminated graphite-epoxy composites

    Science.gov (United States)

    Morton, John; Ho, Henjen

    1992-01-01

    The objectives were to evaluate popular shear test methods for various forms of graphite-epoxy composite materials and to determine the shear response of graphite-epoxy composites with various forms of fiber architecture. Numerical and full-field experimental stress analyses were performed on four shear test configurations for unidirectional and bidirectional graphite-epoxy laminates to assess the uniformity and purity of the shear stress (strain) fields produced in the specimen test section and to determine the material in-plane shear modulus and shear response. The test methods were the 10 deg off-axis, the +/- 45 deg tension, the Iosipescu V-notch, and a compact U-notch specimen. Specimens were prepared from AS4/3501-6 graphite-epoxy panels, instrumented with conventional strain gage rosettes and with a cross-line moire grating, and loaded in a convenient testing machine. The shear responses obtained for each test method and the two methods of specimen instrumentation were compared. In a second phase of the program the shear responses obtained from Iosipescu V-notch beam specimens were determined for woven fabric geometries of different weave and fiber architectures. Again the responses of specimens obtained from strain gage rosettes and moire interferometry were compared. Additional experiments were performed on a bidirectional cruciform specimen which was also instrumented with strain gages and a moire grating.

  11. Numerical investigation of nonlinear interactions between multimodal guided waves and delamination in composite structures

    Science.gov (United States)

    Shen, Yanfeng

    2017-04-01

    This paper presents a numerical investigation of the nonlinear interactions between multimodal guided waves and delamination in composite structures. The elastodynamic wave equations for anisotropic composite laminate were formulated using an explicit Local Interaction Simulation Approach (LISA). The contact dynamics was modeled using the penalty method. In order to capture the stick-slip contact motion, a Coulomb friction law was integrated into the computation procedure. A random gap function was defined for the contact pairs to model distributed initial closures or openings to approximate the nature of rough delamination interfaces. The LISA procedure was coded using the Compute Unified Device Architecture (CUDA), which enables the highly parallelized computation on powerful graphic cards. Several guided wave modes centered at various frequencies were investigated as the incident wave. Numerical case studies of different delamination locations across the thickness were carried out. The capability of different wave modes at various frequencies to trigger the Contact Acoustic Nonlinearity (CAN) was studied. The correlation between the delamination size and the signal nonlinearity was also investigated. Furthermore, the influence from the roughness of the delamination interfaces was discussed as well. The numerical investigation shows that the nonlinear features of wave delamination interactions can enhance the evaluation capability of guided wave Structural Health Monitoring (SHM) system. This paper finishes with discussion, concluding remarks, and suggestions for future work.

  12. Structural health monitoring of composite laminates using piezoelectric and fiber optics sensors

    Science.gov (United States)

    Roman, Catalin

    This research proposes a new approach to structural health monitoring (SHM) for composite laminates using piezoelectric wafer active sensors (PWAS) and fiber optic bragg grating sensors (FBG). One major focus of this research was directed towards extending the theory of laminates to composite beams by combining the global matrix method (GMM) with the stiffness transfer matrix method (STMM). The STMM approach, developed by Rokhlin et al (2002), is unconditionally stable and is more computationally efficient than the transfer matrix method (TMM). Starting from theory, we developed different configurations for composite beams and validated the results from the developed analytical method against experimental data. STMM was then developed for pristine composite beam and delaminated composite beam. We studied the influence of the bonded PWAS by looking at their mode frequencies and amplitudes via experiments and simulations with different sensor positions on pristine and damaged beams, with different delamination sizes and depths. We also extended the TMM and the electro-mechanical (E/M) impedance method for applications to the convergence of TMM of beam vibrations. The focus was on the high-accuracy predictive modeling of the interaction between PWAS and structural waves and vibration using a methodology as in Cuc (2010). We expanded the frequency resonances of a uniform beam from the range of 1-30 kHz previously studied by Cuc (2010) to a higher frequency range of 10-100 kHz and performed the reliability and accuracy analysis (error rates) of all available theoretical models (modal expansion, TMM, and FEM) given experimental data for the uniform beam specimen. Another focus of this research was to explore the use of FBG for fiber composites applications. We performed tests that vary the load on the free end in order to understand the behavior of composite materials under tensile forces and to extend results to ring sensor applications. The last part this research

  13. The effect of bulk-resin CNT-enrichment on damage and plasticity in shear-loaded laminated composites

    KAUST Repository

    Ventura, Isaac Aguilar

    2013-07-01

    One way to improve multi functionality of epoxy-based laminated composites is to dope the resin with carbon nanotubes. Many investigators have focused on the elastic and fracture behavior of such nano-modified polymers under tensile loading. Yet, in real structural applications, laminated composites can exhibit plasticity and progressive damage initiated mainly by shear loading. We investigated the damage and plasticity induced by the addition of carbon nanotubes to the matrix of a glass fiber/epoxy composite system. We characterized both the modified epoxy resin and the associated modified laminates using classical mesoscale analysis. We used dynamic mechanical analysis, scanning electron microscopy, atomic force microscopy and classical mechanical testing to characterize samples with different concentrations of nanofillers. Since the samples were prepared using the solvent evaporation technique, we also studied the influence of this process. We found that in addition to the global increase in elastic regime properties, the addition of carbon nanotubes also accelerates the damage process in both the bulk resin and its associated glass-fiber composite. © 2013 Elsevier Ltd.

  14. Uncertainty quantification for acoustic nonlinearity parameter in Lamb wave-based prediction of barely visible impact damage in composites

    Science.gov (United States)

    Hong, Ming; Mao, Zhu; Todd, Michael D.; Su, Zhongqing

    2017-01-01

    Nonlinear features extracted from Lamb wave signals (e.g., second harmonic generation) are demonstrably sensitive to microscopic damage, such as fatigue and material thermal degradation. While a majority of the existing studies in this context is focused on detecting undersized damage in metallic materials, the present study is aimed at expanding such a detection philosophy to the domain of composites, by linking the relative acoustic nonlinearity parameter (RANP) - a prominent nonlinear signal feature of Lamb waves - to barely visible impact damage (BVID) in composites. Nevertheless, considering immense uncertainties inevitably embedded in acquired signals (due to instrumentation, environment, operation, computation/estimation, etc.) which can adversely obfuscate nonlinear features, it is necessary to quantify the uncertainty of the RANP (i.e., its statistics) in order to enhance decision-making associated with its use as a detection feature. A probabilistic model is established to numerically evaluate the statistical distribution of the RANP. Using piezoelectric wafers, Lamb waves are acquired and processed to produce histograms of RANP estimates in both the healthy and damaged conditions of a CF/EP laminate, to which the model is compared, with good agreement observed between the model-predicted and experimentally-obtained statistic distributions of the RANP. With the model, BVID in the laminate is predicted. The model is further made use of to quantify the level of confidence in damage prediction results based on the concept of a receiver operating characteristic, enabling the practitioners to better understand the obtained results in the presence of uncertainties.

  15. Comparative evaluation of effects of bleaching on color stability and marginal adaptation of discolored direct and indirect composite laminate veneers under in vivo conditions

    National Research Council Canada - National Science Library

    Jain, Veena; Das, Taposh K; Pruthi, Gunjan; Shah, Naseem; Rajendiran, Suresh

    2015-01-01

    .... Bleaching is commonly used for treating discolored teeth. However, the literature is scanty regarding its effect on color and marginal adaptation of direct and indirect composite laminate veneers (CLVs...

  16. Dynamic tensile stress–strain characteristics of carbon/epoxy laminated composites in through-thickness direction

    Directory of Open Access Journals (Sweden)

    Nakai Kenji

    2015-01-01

    Full Text Available The effect of strain rate up to approximately ε̇ = 102/s on the tensile stress–strain properties of unidirectional and cross-ply carbon/epoxy laminated composites in the through-thickness direction is investigated. Waisted cylindrical specimens machined out of the laminated composites in the through-thickness direction are used in both static and dynamic tests. The dynamic tensile stress–strain curves up to fracture are determined using the split Hopkinson bar (SHB. The low and intermediate strain-rate tensile stress–strain relations up to fracture are measured on an Instron 5500R testing machine. It is demonstrated that the ultimate tensile strength and absorbed energy up to fracture increase significantly, while the fracture strain decreases slightly with increasing strain rate. Macro- and micro-scopic examinations reveal a marked difference in the fracture surfaces between the static and dynamic tension specimens.

  17. Effects of interface roughness on the annealing behaviour of laminated Ti-Al composite deformed by hot rolling

    DEFF Research Database (Denmark)

    Du, Y.; Fan, G.H.; Yu, Tianbo;

    2015-01-01

    A laminated Ti-Al composite has been fabricated by hot compaction and hot rolling of alternate layers of commercial purity Ti and Al sheets with a thickness of 200 μm. The hot compaction temperature was 500˚C and in a following step the composite has been reduced 50% in thickness by hot rolling....... The heterogeneity affected the recovery kinetics of the aluminium phase which at 300˚C was faster near the interface than in the middle of the Al layer. This effect of a heterogeneous interface is of relevance when optimizing the thermomechanical processing of the composite to obtain high strength and formability...

  18. Enhanced magnetoelectric effects in laminate composites of Terfenol-D/Pb(Zr,Ti)O-3 under resonant drive

    OpenAIRE

    Dong, Shuxiang; Cheng, J. R.; Li, Jiefang; Viehland, Dwight D.

    2003-01-01

    We have found that laminate composites consisting of longitudinally magnetized magnetostrictive Terfenol-D and longitudinally poled piezoelectric Pb(Zr,Ti)O-3 layers have dramatically enhanced magnetoelectric effects when driven near resonance. The maximum induced magnetoelectric voltage at resonance was similar to10 Vp/Oe, which is similar to10(2) times higher than previous reports at subresonant frequencies. (C) 2003 American Institute of Physics.

  19. Stress analysis and damage evaluation of flawed composite laminates by hybrid-numerical methods

    Science.gov (United States)

    Yang, Yii-Ching

    1992-01-01

    Structural components in flight vehicles is often inherited flaws, such as microcracks, voids, holes, and delamination. These defects will degrade structures the same as that due to damages in service, such as impact, corrosion, and erosion. It is very important to know how a structural component can be useful and survive after these flaws and damages. To understand the behavior and limitation of these structural components researchers usually do experimental tests or theoretical analyses on structures with simulated flaws. However, neither approach has been completely successful. As Durelli states that 'Seldom does one method give a complete solution, with the most efficiency'. Examples of this principle is seen in photomechanics which additional strain-gage testing can only average stresses at locations of high concentration. On the other hand, theoretical analyses including numerical analyses are implemented with simplified assumptions which may not reflect actual boundary conditions. Hybrid-Numerical methods which combine photomechanics and numerical analysis have been used to correct this inefficiency since 1950's. But its application is limited until 1970's when modern computer codes became available. In recent years, researchers have enhanced the data obtained from photoelasticity, laser speckle, holography and moire' interferometry for input of finite element analysis on metals. Nevertheless, there is only few of literature being done on composite laminates. Therefore, this research is dedicated to this highly anisotropic material.

  20. Designing of Hybrid Structured Glass Laminated Transparent Nano Composites through Vacuum infusion Technique

    Science.gov (United States)

    Mukherji, A.; Tarapure, N. D.; Wakure, G. N.

    2017-05-01

    Glass is the most commonly used transparent material. However, glass is not suitable in applications where low weight, high strength is required. The present invention comprises a method of making a Transparent Glass Laminated Nano composite product. The product contains a Bidirectionally oriented E-Glass Fabric an essentially bidirectional yarn woven fabrics is stretched Bidirectionally by specially fabricated steel frame associated with both co and counter rotating device. These fibers include glass fibrics/cloths or mixtures of any of these. The synthetic fiber may be any synthetic silica based oven waived bi-directional or Uni-directional fabrics. Engaged gear provided in the device develops uniform tension on fabric, in both direction. Nano particle dispersed resin to be used is formulated with their respective curing agents and extenders. The formulated resin contains 0.1-0.5% of Nano additives and the product composed from 5-10 % of Glass fabric, between 10 to 20 % of ordinary glass, and between 60-80 % of the product is the Nano particles dispersed formulated resin, all measured by volume.

  1. Aminophenoxycyclotriphosphazene cured epoxy resins and the composites, laminates, adhesives and structures thereof

    Science.gov (United States)

    Kumar, Devendra (Inventor); Fohlen, George M. (Inventor); Parker, John A. (Inventor)

    1977-01-01

    Aminophenoxy cyclotriphosphazenes such as hexakis (4-aminophenoxy) cyclotriphosphazene and tris (4-aminophenoxy)-tris phenoxy cyclotriphosphazene are used as curing agents for epoxy resins. These 1,2-epoxy resins are selected from di- or polyepoxide containing organic moieties of the formula (CH2-CHO-CH2) m-W-R-W- (CH2CH-CH2O)m where R is diphenyl dimethylmethane, diphenylmethane; W is a nitrogen or oxygen atom; and m is 1 when W is oxygen and 2 when W is nitrogen. The resins are cured thermally in stages at between about 110 to 135 C for between about 1 and 10 min, then at between about 175 to 185 C for between 0.5 to 10 hr and post cured at between about 215 and 235 C for between 0.1 and 2 hr. These resins are useful for making fire resistant elevated temperature stable composites, laminates, molded parts, and adhesives and structures, usually for aircraft secondary structures and for spacecraft construction.

  2. Application of the quadrilateral area coordinate method: a new element for laminated composite plate bending problems

    Institute of Scientific and Technical Information of China (English)

    Song Cen; Xiangrong Fu; Yuqiu Long; Hongguang Li; Zhenhan Yao

    2007-01-01

    Recently, some new quadrilateral finite elements were successfully developed by the Quadrilateral Area Coordinate (QAC) method. Compared with those traditional models using isoparametric coordinates, these new models are less sensitive to mesh distortion. In this paper, a new displacement-based, 4-node 20-DOF (5-DOF per node)quadrilateral bending element based on the first-order shear deformation theory for analysis of arbitrary laminated composite plates is presented. Its bending part is based on the element AC-MQ4, a recent-developed high-performance Mindlin-Reissner plate element formulated by QAC method and the generalized conforming condition method; and its in-plane displacement fields are interpolated by bilinear shape functions in isoparametric coordinates. Furthermore,the hybrid post-processing procedure, which was firstly proposed by the authors, is employed again to improve the stress solutions, especially for the transverse shear stresses. The resulting element, denoted as AC-MQ4-LC, exhibits excellent performance in all linear static and dynamic numerical examples. It demonstrates again that the QAC method, the generalized conforming condition method, and the hybrid post-processing procedure are efficient tools for developing simple, effective and reliable finite element models.

  3. Active Vibration Control of Laminated Composite Plates by using External Patches

    Directory of Open Access Journals (Sweden)

    N. S. Sunil Varma

    2017-05-01

    Full Text Available The concept of suppressing vibrations caused by external or internal stimulus has been evolving from a long time and there have been several techniques to suppress these vibrations involving spring mass dampeners and inertial mass actuators but the technique of active vibration control is more efficient in its ability to reduce vibrations to great extent. The field applications that active vibration control can be employed in, are vast ranging from structures like automobile engines, vehicle chassis, to airplane wings. The key significant improvement in using this technique is that the actuatosr placed reduces the vibrations of all modal frequencies more efficiently compared to other techniques that are efficient only in suppressing high-frequency modes. The main points to be considered in this technique are the positioning, number and the size of actuator/patch. In this study we used ANSYS 15.0 to analyse the impact of patch position, size and number on the natural frequency and displacement of the actual host structure (in our case laminated composite plate by observing the strain values and root occurrence in case of the host structure. We used Piezo ceramic as an actuator/patch to suppress vibrations. The positional influence is shown to have a profound impact on reducing host structure deformation to a significant extent. The Analysis we have done paves a way for using active vibration control technique efficiently; since it involves the study of all the key parameters that helps in attenuating the vibrations.

  4. Mechanical properties and crack propagation behaviors of laminated Ti/Al2O3 composite

    Directory of Open Access Journals (Sweden)

    Chao Wu

    2014-12-01

    Full Text Available Laminated Ti/Al2O3 composite was fabricated by tape casting and vacuum hot-pressing sintering with intent to research mechanical properties including the fracture strength and toughness. The results showed that the flexural strength and fracture toughness improved according to the amount of layers. When the amount of layers was 35, the flexural strength and fracture toughness reached 361 MPa and 9.72 MPa m1/2, respectively. Based on the observation of microstructures, it was concluded that the improvement of mechanical properties was attributed to various crack propagation (such as crack deflection, crack bifurcation, crack termination and interface dissociation. The characterization of EDX and XRD at interfaces indicated that the initiative diffusion of O2− from Al2O3 to Ti layer led to the passive diffusion of Al3+ (aggregating near the interface and reacted with Ti to form Ti3Al, Ti[O] and AlTiO2 solid solution.

  5. Stacking sequence and shape optimization of laminated composite plates via a level-set method

    Science.gov (United States)

    Allaire, G.; Delgado, G.

    2016-12-01

    We consider the optimal design of composite laminates by allowing a variable stacking sequence and in-plane shape of each ply. In order to optimize both variables we rely on a decomposition technique which aggregates the constraints into one unique constraint margin function. Thanks to this approach, an exactly equivalent bi-level optimization problem is established. This problem is made up of an inner level represented by the combinatorial optimization of the stacking sequence and an outer level represented by the topology and geometry optimization of each ply. We propose for the stacking sequence optimization an outer approximation method which iteratively solves a set of mixed integer linear problems associated to the evaluation of the constraint margin function. For the topology optimization of each ply, we lean on the level set method for the description of the interfaces and the Hadamard method for boundary variations by means of the computation of the shape gradient. Numerical experiments are performed on an aeronautic test case where the weight is minimized subject to different mechanical constraints, namely compliance, reserve factor and buckling load.

  6. Vibration and acoustic response of an orthotropic composite laminated plate in a hygroscopic environment.

    Science.gov (United States)

    Zhao, Xin; Geng, Qian; Li, Yueming

    2013-03-01

    This paper is a study of the vibration and acoustic response characteristics of orthotropic laminated composite plate with simple supported boundary conditions excited by a harmonic concentrated force in a hygroscopic environment. First the natural vibration of the plate with the in-plane forces induced by hygroscopic stress is obtained analytically. Secondly, the sound pressure distribution of the plate at the far field is obtained using the Rayleigh integral. Furthermore, the sound radiation efficiency is deduced. Third, different ratios of elastic modulus in material principal directions are set to research the effects of increasing stiffness of the orthotropic plate on the vibration and acoustic radiation characteristics. Finally, to verify the theoretical solution, numerical simulations are also carried out with commercial finite software. It is found that the natural frequencies decrease with the increase of the moisture content and the first two order modes interconvert at high moisture content. The dynamic response and sound pressure level float to lower frequencies with elevated moisture content. Acoustic radiation efficiency generally floats to the low frequencies and decreases with an increase of moisture content. The dynamic and acoustic responses reduce and the coincidence frequency decreases with the enhanced stiffness.

  7. Nonlinear optical properties of Au/PVP composite thin films

    Institute of Scientific and Technical Information of China (English)

    Shen Hong; Cheng Bo-Lin; Lu Guo-Wei; Wang Wei-Tian; Guan Dong-Yi; Chen Zheng-Hao; Yang Guo-Zhen

    2005-01-01

    Colloidal Au and poly(vinylpyrrolidone) (PVP) composite thin films are fabricated by spin-coating method. Linear optical absorption measurements of the Au/PVP composite films indicate an absorption peak around 530 nm due to the surface plasmon resonance of gold nanoparticles. Nonlinear optical properties are studied using standard Z-scan technique, and experimental results show large optical nonlinearities of the Au/PVP composite films. A large value of films.

  8. Thermally-induced shapes of rigid FR-4 electrical laminates

    Science.gov (United States)

    Lyle, Phra Douglas

    In the process of a laminate cooling from the curing temperature to room temperature, a substantial level of thermal residual stresses develop. These residual thermal stresses arise due to the mismatch of the thermal expansion coefficient between lamina and between the reinforcing fibers and the matrix resin, generating warpage, or out of plane deformations, when the laminate is not symmetric about the midplane of the composite. Classical lamination theory has been used to predict the warped shape of an asymmetric laminate; this theory suggests that the cooled room temperature shape to be a stable anticlastic or saddle shape. In the 80s, nonlinear theories were developed in order to explain observations for (0/90) sbT cross-ply laminates that cool to a cylindrical shape and to predict the observed phenomena of an occasional "snap through" between two stable cylindrical shapes. Recently, the nonlinear approach has been successfully modified for the analysis of a square angle-ply laminate, allowing an even greater number of laminates to be evaluated. A rigid FR-4 electrical circuit board is a composite laminate that is designed to be symmetrical; however, after cooling from the press cycle or after cooling from other processing thermal excursions, warpage can occur. One potential cause for this warpage can be inadvertently introduced process or material nonuniformities. This investigation develops an FR-4 electrical laminate model that can transform selected material and process variations into input for the mechanical and thermal matrices required in the formulation of both classical lamination and the nonlinear theories. The output is the predicted warpage, for each theory, for each of the selected material and process variations. These warpage outputs are graphically displayed, quantified and compared for the classical lamination theory and for the four recent nonlinear theories. Also, the predicted warpage deformations are stack ranked in order to provide an

  9. A review of strategies for improving the degradation properties of laminated continuous-fiber/epoxy composites with carbon-based nanoreinforcements

    KAUST Repository

    Lubineau, Gilles

    2012-06-01

    Continuous-fiber/epoxy-matrix laminated composites are a key structural material for aeronautical and aerospace applications. Introducing nanoscale reinforcements to these materials is a possible way to achieve improved mechanical properties. To date, much work has been done on nano-reinforced polymers. However, few systematic studies concerning the effect of the nanoreinforcements on the mechanical properties on laminated composites were conducted. This paper presents a systematic review of the mechanisms of degradation in laminated structures and considers various nanoreinforcement strategies in the light of well-known mechanisms of degradation and phenomenologies in classical laminated composites. We also discuss various nanoreinforcement strategies in terms of their potential to reduce degradation on every scale. In addition, we review studies conducted on the role that nanoreinforcements play in mechanical properties involved in structural simulation and design. The degradation mechanisms are systematically considered to provide a full picture of each reinforcement strategy. © 2012 Elsevier Ltd. All rights reserved.

  10. Finite Element Analysis of Internally Ply Drop-off Composite Laminates

    Directory of Open Access Journals (Sweden)

    Priyanka Dhurvey and N D Mittal

    2012-11-01

    Full Text Available Tapered laminated structures, which are formed by dropping off some of the plies at discrete positions over the laminate, have received much attention from researchers because of their structural tailoring capabilities, damage tolerance, and their potential for creating significant weight savings in engineering applications. The inherent weakness of this construction is the presence of material and geometric discontinuities at ply drop region that induce premature interlaminar failure at interfaces between dropped and continuous plies.

  11. Processing and Evaluation of 3D-Reinforced Needled Composite Laminate

    Science.gov (United States)

    2012-09-01

    laminates using the Vacuum Assisted Resin Transfer Molding ( VARTM ) process. Specimens were then cut from the cured parent panels and inspected with...before the panel was processed with VARTM . A significant quantity of aramid could be seen protruding from the backside of the laminate as well as...embedded in the foam backer, indicating inefficiency in this handheld processing method. After the panel was processed with VARTM , the TTR was observed

  12. Post-impact performance of composites; Predicting Compression after Impact (CAI) in composite laminates

    NARCIS (Netherlands)

    Esrall, F.

    2013-01-01

    Impact damage has been known to seriously limit the performance of composite aircraft structures. In the preliminary design phase, tens of thousands of subparts need to be analyzed for impact. Over the years, many approaches have been proposed to study the creation of impact damage and to determine

  13. Lamb wave sensing using fiber Bragg grating sensors for delamination detection in composite laminates

    Science.gov (United States)

    Takeda, N.; Okabe, Y.; Kuwahara, J.; Kojima, S.

    2005-05-01

    The authors are constructing a damage detection system using ultrasonic waves. In this system, a piezo-ceramic actuator generates Lamb waves in a CFRP laminate. After the waves propagate in the laminate, transmitted waves are received by a fiber Bragg grating (FBG) sensor attached on the laminate using a newly developed high-speed optical wavelength interrogation system. At first, the optimal gauge length of the FBG to detect ultrasonic waves was investigated through theoretical simulations and experiments. Then, the directional sensitivity of the FBG to ultrasonic waves was evaluated experimentally. On the basis of the above results, the 1mm FBG sensors were applied to the detection of Lamb waves propagated in carbon fiber reinforced plastic (CFRP) cross-ply laminates. The piezo-actuator was put on the laminate about 50mm away from the FBG sensor glued on the laminate, and three-cycle sine waves of 300kHz were excited repeatedly. The waveforms obtained by the FBG showed that S0 and A0 modes could be detected appropriately. Then, artificial delamination was made in the laminate by removing of a Teflon sheet embedded in the 0/90 interface after the manufacturing. When the Lamb waves passed through the delamination, the amplitude decreased and a new wave mode appeared. These phenomena could be well simulated using a finite element method. Furthermore, since the amplitude and the velocity of the new mode increased with an increase in the delamination length, this system has a potential to evaluate the interlaminar delamination length quantitatively.

  14. Penetration resistance and ballistic-impact behavior of Ti/TiAl3 metal/intermetallic laminated composites (MILCs: A computational investigation

    Directory of Open Access Journals (Sweden)

    Jennifer S. Snipes

    2016-06-01

    Full Text Available A comprehensive computational engineering analysis is carried out in order to assess suitability of the Ti/TiAl3 metal/intermetallic laminated composites (MILCs for use in both structural and add-on armor applications. This class of composite materials consists of alternating sub-millimeter thick layers of Ti (the ductile and tough constituent and TiAl3 (the stiff and hard constituent. In recent years, this class of materials has been investigated for potential use in light-armor applications as a replacement for the traditional metallic or polymer-matrix composite materials. Within the computational analysis, an account is given to differing functional requirements for candidate materials when used in structural and add-on ballistic armor. The analysis employed is of a transient, nonlinear-dynamics, finite-element character, and the problem investigated involves normal impact (i.e. under zero obliquity angle of a Ti/TiAl3 MILC target plate, over a range of incident velocities, by a fragment simulating projectile (FSP. This type of analysis can provide more direct information regarding the ballistic limit of the subject armor material, as well as help with the identification of the nature and the efficacy of various FSP material-deformation/erosion and kinetic-energy absorption/dissipation phenomena and processes. The results obtained clearly revealed that Ti/TiAl3 MILCs are more suitable for use in add-on ballistic, than in structural armor applications.

  15. A simple laminate theory using the orthotropic viscoplasticity theory based on overstress. I - In-plane stress-strain relationships for metal matrix composites

    Science.gov (United States)

    Krempl, Erhard; Hong, Bor Zen

    1989-01-01

    A macromechanics analysis is presented for the in-plane, anisotropic time-dependent behavior of metal matrix laminates. The small deformation, orthotropic viscoplasticity theory based on overstress represents lamina behavior in a modified simple laminate theory. Material functions and constants can be identified in principle from experiments with laminae. Orthotropic invariants can be repositories for tension-compression asymmetry and for linear elasticity in one direction while the other directions behave in a viscoplastic manner. Computer programs are generated and tested for either unidirectional or symmetric laminates under in-plane loading. Correlations with the experimental results on metal matrix composites are presented.

  16. Understanding the Percolation Characteristics of Nonlinear Composite Dielectrics

    Science.gov (United States)

    Yang, Xiao; Hu, Jun; Chen, Shuiming; He, Jinliang

    2016-08-01

    Nonlinear composite dielectrics can function as smart materials for stress control and field grading in all fields of electrical insulations. The percolation process is a significant issue of composite dielectrics. However, the classic percolation theory mainly deals with traditional composites in which the electrical parameters of both insulation matrix and conducting fillers are independent of the applied electric field. This paper measured the nonlinear V-I characteristics of ZnO microvaristors/silicone rubber composites with several filler concentrations around an estimated percolation threshold. For the comparison with the experiment, a new microstructural model is proposed to simulate the nonlinear conducting behavior of the composite dielectrics modified by metal oxide fillers, which is based on the Voronoi network and considers the breakdown feature of the insulation matrix for near percolated composites. Through both experiment and simulation, the interior conducting mechanism and percolation process of the nonlinear composites were presented and a specific percolation threshold was determined as 33%. This work has provided a solution to better understand the characteristics of nonlinear composite dielectrics.

  17. A critical evaluation of theories for predicting microcracking in composite laminates

    Science.gov (United States)

    Nairn, John A.; Hu, Shoufeng; Bark, Jong S.

    1993-01-01

    We present experimental results on 21 different layups of Hercules AS4 carbon fiber/3501-6 epoxy laminates. All laminates had 90 deg plies; some had them in the middle, while some had them on a free surface. During tensile loading, the first form of damage in all laminates was microcracking of the 90 deg plies. For each laminate, we recorded both the crack density and the complete distribution of crack spacings as a function of the applied load. By rearranging various microcracking theories, we developed a master-curve approach that permitted plotting the results from all laminates on a single plot. By comparing master-curve plots for different theories, it was possible to critically evaluate the quality of those theories. We found that a critical-energy-release-rate criterion calculated using a 2D variational stress analysis gave the best results. All microcracking theories based on a strength-failure criteria gave poor results. All microcracking theories using 1D stress analyses, regardless of the failure criterion, also gave poor results.

  18. Composite structures for the enhancement of nonlinear optical materials.

    Science.gov (United States)

    Neeves, A E; Birnboim, M H

    1988-12-01

    Calculations of the nonlinear optical behavior are developed for model composites consisting of nanospheres with a metallic core and a nonlinear shell suspended in a nonlinear medium. The concept for the enhancement of optical phase conjugation from all these nonlinear regions is that the optical field can be concentrated both inside and in the neighborhood of the metallic core, aided by surface-mediated plasmon resonance. Calculations for gold cores and aluminum cores indicate that phase-conjugate reflectivity enhancements of 10(8) may be possible.

  19. Impact damage detection in smart composites using nonlinear acoustics—cointegration analysis for removal of undesired load effect

    Science.gov (United States)

    Dao, Phong B.; Klepka, Andrzej; Pieczonka, Łukasz; Aymerich, Francesco; Staszewski, Wieslaw J.

    2017-03-01

    The paper presents a reliable methodology—based on nonlinear acoustics—for impact damage detection in composite materials. The nonlinear vibro-acoustic wave modulation technique is used to detect damage. The problem of operational variability of the method with respect to the selection of frequency and amplitude of low-frequency (LF) modal excitation is investigated. This problem is addressed using the concept of stationarity of time series of vibro-acoustic data. Cointegration analysis is employed to compensate for the effect of variable operational conditions associated with LF modal (or vibration) excitation in nonlinear vibro-acoustic wave modulations. Analysis of stationary statistical characteristics of vibro-acoustic responses—after cointegration analysis—are used for damage detection. The proposed method is validated using vibro-acoustic data from laminated composite plates and composite sandwich panels. The results demonstrate that the proposed approach can effectively compensate for the effect of LF modal excitation on nonlinear vibro-acoustic wave modulations and detect the damage more accurately and robustly than the existing nonlinear acoustics based on the analysis of modulation sidebands.

  20. On micro to mesoscale homogenization of electrical properties for damaged laminated composites (and their potential applications in electrical tomography)

    KAUST Repository

    Selvakumaran, Lakshmi

    2015-12-01

    Efficient and optimal use of composites in structures requires tools to monitor and capture the complex degradation that can occur within the laminates over time. Structural health monitoring (SHM) techniques uses sensors/actuators on the structure to progressively monitor the health of the structure with minimal manual intervention. Electrical tomography (ET) is a SHM technique that uses voltage measurements from the surface of the laminate to reconstruct a conductivity map of the structure. Since damage has been shown to modify the conductivity of the laminate, the conductivity map can provide an indirect measure of the damage within the material. Studies have shown the capability of ET to identify macroscale damage due to impact. But, little has been done to quantitatively assess damage using ET. In this work, we present a theoretical framework to link degradation mechanisms occuring at the microscale to the conductivity at the mesoscale through damage indicators. The mesoscale damage indicators are then shown to be intrinsic to the ply. Next, we use the knowledge obtained through mesoscale homogenization to study the detectability of transverse cracks. Last, we show how the mesoscale homogenization participates in regularization of the inverse problem and in the quantitative assessment of the reconstructed conductivity map. This is as such the first step towards turning ET into a viable quantitative health monitoring technique.

  1. Damping and vibration control of unidirectional composite laminates using add-on viscoelastic materials

    Science.gov (United States)

    Sun, C. T.; Sankar, B. V.; Rao, V. S.

    1990-06-01

    This paper describes the development of an efficient finite element model for dynamic analysis of laminated beams treated by a constrained viscoelastic layer. The finite element model is designed so as to represent the viscoelastic core shear accurately. An offset-beam element which takes shear deformation into account and is specially suited for modeling such laminated beams is developed. The laminated beam and constraining layer are modeled by using the offset beam element. The viscoelastic core is modeled by using plane finite elements which are compatible with the beam elements. System damping and tip displacement are computed and compared with those measured experimentally by using the impulse-frequency response technique. Results show that dynamic response is improved by use of such damping treatments.

  2. Influence of Shear Stiffness Degradation on Crack Paths in Uni-Directional Composite Laminates

    Science.gov (United States)

    Satyanarayana, Arunkumar; Bogert, Phil B.

    2017-01-01

    Influence of shear stiffness degradation in an element, due to damage, on crack paths in uni-directional laminates has been demonstrated. A new shear stiffness degradation approach to improve crack path prediction has been developed and implemented in an ABAQUS/Explicit frame work using VUMAT. Three progressive failure analysis models, built-in ABAQUS (TradeMark), original COmplete STress Reduction (COSTR) and the modified COSTR damage models have been utilized in this study to simulate crack paths in five unidirectional notched laminates, 15deg, 30deg, 45deg, 60deg and 75deg under uniaxial tension load. Results such as crack paths and load vs. edge displacement curves are documented in this report. Modified COSTR damage model shows better accuracy in predicting crack paths in all the uni-directional laminates compared to the ABAQUS (TradeMark) and the original COSTR damage models.

  3. Critical time step for a bilinear laminated composite Mindlin shell element.

    Energy Technology Data Exchange (ETDEWEB)

    Hammerand, Daniel Carl

    2004-06-01

    The critical time step needed for explicit time integration of laminated shell finite element models is presented. Each layer is restricted to be orthotropic when viewed from a properly oriented material coordinate system. Mindlin shell theory is used in determining the laminated response that includes the effects of transverse shear. The effects of the membrane-bending coupling matrix from the laminate material model are included. Such a coupling matrix arises even in the case of non-symmetric lay-ups of differing isotropic layers. Single point integration is assumed to be used in determining a uniform strain response from the element. Using a technique based upon one from the literature, reduced eigenvalue problems are established to determine the remaining non-zero frequencies. It is shown that the eigenvalue problem arising from the inplane normal and shear stresses is decoupled from that arising from the transverse shear stresses. A verification example is presented where the exact and approximate results are compared.

  4. Process Modelling of Curing Process-Induced Internal Stress and Deformation of Composite Laminate Structure with Elastic and Viscoelastic Models

    Science.gov (United States)

    Li, Dongna; Li, Xudong; Dai, Jianfeng

    2017-08-01

    In this paper, two kinds of transient models, the viscoelastic model and the linear elastic model, are established to analyze the curing deformation of the thermosetting resin composites, and are calculated by COMSOL Multiphysics software. The two models consider the complicated coupling between physical and chemical changes during curing process of the composites and the time-variant characteristic of material performance parameters. Subsequently, the two proposed models are implemented respectively in a three-dimensional composite laminate structure, and a simple and convenient method of local coordinate system is used to calculate the development of residual stresses, curing shrinkage and curing deformation for the composite laminate. Researches show that the temperature, degree of curing (DOC) and residual stresses during curing process are consistent with the study in literature, so the curing shrinkage and curing deformation obtained on these basis have a certain referential value. Compared the differences between the two numerical results, it indicates that the residual stress and deformation calculated by the viscoelastic model are more close to the reference value than the linear elastic model.

  5. Nonlinear damage detection in composite structures using bispectral analysis

    Science.gov (United States)

    Ciampa, Francesco; Pickering, Simon; Scarselli, Gennaro; Meo, Michele

    2014-03-01

    Literature offers a quantitative number of diagnostic methods that can continuously provide detailed information of the material defects and damages in aerospace and civil engineering applications. Indeed, low velocity impact damages can considerably degrade the integrity of structural components and, if not detected, they can result in catastrophic failure conditions. This paper presents a nonlinear Structural Health Monitoring (SHM) method, based on ultrasonic guided waves (GW), for the detection of the nonlinear signature in a damaged composite structure. The proposed technique, based on a bispectral analysis of ultrasonic input waveforms, allows for the evaluation of the nonlinear response due to the presence of cracks and delaminations. Indeed, such a methodology was used to characterize the nonlinear behaviour of the structure, by exploiting the frequency mixing of the original waveform acquired from a sparse array of sensors. The robustness of bispectral analysis was experimentally demonstrated on a damaged carbon fibre reinforce plastic (CFRP) composite panel, and the nonlinear source was retrieved with a high level of accuracy. Unlike other linear and nonlinear ultrasonic methods for damage detection, this methodology does not require any baseline with the undamaged structure for the evaluation of the nonlinear source, nor a priori knowledge of the mechanical properties of the specimen. Moreover, bispectral analysis can be considered as a nonlinear elastic wave spectroscopy (NEWS) technique for materials showing either classical or non-classical nonlinear behaviour.

  6. A Comprehensive Study on Damage Tolerance Properties of Notched Composite Laminates.

    Science.gov (United States)

    1988-02-01

    Input data required to run the code include the geometry for the overall laminate specimen shape, the applied load and boundary conditions, the laminate...or delamination near the notch. Appendix V contains the user’s guide in which a considerable detail about the code 5 is discussed. To help run the...C. (a)i Figure 4. Fite Lierient ?:odel for the Specimen Contdiiiing A S0,01 HiIt 87 W% . 1 DIV. -150Ok1’a 1 DIV. =7 kiu1 I DIV. -𔃼 kPa. 1 DIV. 15

  7. Effective nonlinear AC response to composite with spherical particles

    Institute of Scientific and Technical Information of China (English)

    Chen Xiao-Gang; Liang Fang-Chu; Wei En-Bo

    2005-01-01

    An effective nonlinear alternative-current (AC) response to granular nonlinear-composite with spherical inclusions embedded in a host medium under the action of an external AC field is investigated by using a perturbation approach.The local potentials of composite at higher harmonics are derived both in a region of local inclusion particles and in a local host region under the action of a sinusoidal field E1 sinωt + E3sin3ωt. An effective nonlinear-response to composite and the relationship between the effective nonlinear-responses at the fundamental frequency and the third harmonics are also studied for the spherical inclusions in a dilute limit.

  8. Parametric study on nonlinear vibration of composite truss core sandwich plate with internal resonance

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jia Nen; Liu, Jun [Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System, Tianjin University of Technology, Tianjin (China); Zhang, Wei; Yao, Ming Hui [College of Mechanical Engineering, Beijing University of Technology, Beijing (China); Sun, Min [School of Science, Tianjin Chengjian University, Tianjin (China)

    2016-09-15

    Nonlinear vibrations of carbon fiber reinforced composite sandwich plate with pyramidal truss core are investigated. The governing equation of motion for the sandwich plate is derived by using a Zig-Zag theory under consideration of geometrically nonlinear. The natural frequencies of sandwich plates with different dimensions are calculated and compared with those obtained from the classic laminated plate theory and Reddy's third-order shear deformation plate theory. The frequency responses and waveforms of the sandwich plate when 1:3 internal resonance occurs are obtained, and the characteristics of the internal resonance are discussed. The influences of layer number of face sheet, strut radius, core height and inclination angle on the nonlinear responses of the sandwich plate are analyzed. The results demonstrate that the strut radius and inclination angle mainly affect the resonance frequency band of the sandwich plate, and the layer number and core height not only influence the resonance frequency band but also significantly affect the response amplitude.

  9. Comparison of Damage Path Predictions for Composite Laminates by Explicit and Standard Finite Element Analysis Tools

    Science.gov (United States)

    Bogert, Philip B.; Satyanarayana, Arunkumar; Chunchu, Prasad B.

    2006-01-01

    Splitting, ultimate failure load and the damage path in center notched composite specimens subjected to in-plane tension loading are predicted using progressive failure analysis methodology. A 2-D Hashin-Rotem failure criterion is used in determining intra-laminar fiber and matrix failures. This progressive failure methodology has been implemented in the Abaqus/Explicit and Abaqus/Standard finite element codes through user written subroutines "VUMAT" and "USDFLD" respectively. A 2-D finite element model is used for predicting the intra-laminar damages. Analysis results obtained from the Abaqus/Explicit and Abaqus/Standard code show good agreement with experimental results. The importance of modeling delamination in progressive failure analysis methodology is recognized for future studies. The use of an explicit integration dynamics code for simple specimen geometry and static loading establishes a foundation for future analyses where complex loading and nonlinear dynamic interactions of damage and structure will necessitate it.

  10. A study on nonlinear finite element analysis of laminated rubber bearings. Pt.1. Development of evaluation method for mechanical properties of laminated rubber bearings for horizontal base isolation system considering volumetric deformation of rubber material

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Akihiro; Ohtori, Yasuki; Yabana, Shuichi; Hirata, Kazuta [Central Research Inst. of Electric Power Industry, Abiko, Chiba (Japan). Abiko Research Lab

    1999-04-01

    The purpose of this research is to develop the evaluation method for mechanical properties of laminated rubber bearings by nonlinear finite element method (FEM) considering the volumetric deformation of natural rubber material. Relationship between pressure and volumetric strain of the natural rubber is obtained from the volumetric tests and is introduced into user-subroutine of the FEM code (ABAQUS). Finite element analyses of natural rubber bearings (NRB) and the natural rubber bearing with lead plug (LRB) are carried out. The results may be summarized as follows; 1) Horizontal, vertical stiffness and effect of shear deformation on vertical stiffness of natural rubber bearings that have various shape are simulated with enough accuracy. 2) Horizontal and vertical stiffness of LRB are also simulated well. (author)

  11. Modeling of delamination in carbon/epoxy composite laminates under four point bending for damage detection and sensor placement optimization

    Science.gov (United States)

    Adu, Stephen Aboagye

    Laminated carbon fiber-reinforced polymer composites (CFRPs) possess very high specific strength and stiffness and this has accounted for their wide use in structural applications, most especially in the aerospace industry, where the trade-off between weight and strength is critical. Even though they possess much larger strength ratio as compared to metals like aluminum and lithium, damage in the metals mentioned is rather localized. However, CFRPs generate complex damage zones at stress concentration, with damage progression in the form of matrix cracking, delamination and fiber fracture or fiber/matrix de-bonding. This thesis is aimed at performing; stiffness degradation analysis on composite coupons, containing embedded delamination using the Four-Point Bend Test. The Lamb wave-based approach as a structural health monitoring (SHM) technique is used for damage detection in the composite coupons. Tests were carried-out on unidirectional composite coupons, obtained from panels manufactured with pre-existing defect in the form of embedded delamination in a laminate of stacking sequence [06/904/0 6]T. Composite coupons were obtained from panels, fabricated using vacuum assisted resin transfer molding (VARTM), a liquid composite molding (LCM) process. The discontinuity in the laminate structure due to the de-bonding of the middle plies caused by the insertion of a 0.3 mm thick wax, in-between the middle four (4) ninety degree (90°) plies, is detected using lamb waves generated by surface mounted piezoelectric (PZT) actuators. From the surface mounted piezoelectric sensors, response for both undamaged (coupon with no defect) and damaged (delaminated coupon) is obtained. A numerical study of the embedded crack propagation in the composite coupon under four-point and three-point bending was carried out using FEM. Model validation was then carried out comparing the numerical results with the experimental. Here, surface-to-surface contact property was used to model the

  12. A multi-layer triangular membrane finite element for the forming simulation of laminated composites

    NARCIS (Netherlands)

    Thije, ten R.H.W.; Akkerman, R.

    2009-01-01

    Continuous fibre reinforced thermoplastics offer a cost reduction compared to thermosets due to promising fast production methods like diaphragm forming and rubber pressing. Forming experiments of pre-consolidated four-layer 8H satin weave PPS laminates on a dome geometry demonstrated that inter-ply

  13. Influence of SMA reinforcement on the impact resistance of GFRP composite laminates under different temperatures

    Indian Academy of Sciences (India)

    K PAZHANIVEL; G B BHASKAR; A ELAYAPERUMAL; P ANANDAN; S ARUNACHALAM

    2016-06-01

    Plain glass fibre-reinforced polymeric (GFRP) laminates and GFRP reinforced with randomly oriented short strips of shape memory alloy (SMA) were prepared by hand lay-up method. The SMA strip reinforcement was placed at 0.75 $\\times$ thickness of the laminate with weight fractions of 2, 4 and 6%. The specimens were exposed to drop weight impact test and the experiments were conducted at a constant impact velocity of 2.80 m s$^{−1}$ with different test temperatures such as 303, 333 and 363 K. The impact damage area was evaluated using lighting technique and fracture response was analysed using scanning electron microscopic (SEM) images. Absorption of impact energyand damage area due to low velocity impact were calculated. It was observed that with the higher temperature, the SMA/GFRP laminates exhibit marginally-enhanced damage resistance compared to the plain GFRP laminates. Also, addition of SMA reinforcement was not contributing much to the impact resistance at higher temperature.

  14. Numerical studies of the nonlinear properties of composites

    Science.gov (United States)

    Zhang, X.; Stroud, D.

    1994-01-01

    Using both numerical and analytical techniques, we investigate various ways to enhance the cubic nonlinear susceptibility χe of a composite material. We start from the exact relation χe =tsumipiχii,lin/ E40, where χi and pi are the cubic nonlinear susceptibility and volume fraction of the ith component, E0 is the applied electric field, and i,lin is the expectation value of the electric field in the ith component, calculated in the linear limit where χi=0. In our numerical work, we represent the composite by a random resistor or impedance network, calculating the electric-field distributions by a generalized transfer-matrix algorithm. Under certain conditions, we find that χe is greatly enhanced near the percolation threshold. We also find a large enhancement for a linear fractal in a nonlinear host. In a random Drude metal-insulator composite χe is hugely enhanced especially near frequencies which correspond to the surface-plasmon resonance spectrum of the composite. At zero frequency, the random composite results are reasonably well described by a nonlinear effective-medium approximation. The finite-frequency enhancement shows very strong reproducible structure which is nearly undetectable in the linear response of the composite, and which may possibly be described by a generalized nonlinear effective-medium approximation. The fractal results agree qualitatively with a nonlinear differential effective-medium approximation. Finally, we consider a suspension of coated spheres embedded in a host. If the coating is nonlinear, we show that χe/χcoat>>1 near the surface-plasmon resonance frequency of the core particle.

  15. Processing, Dynamic Deformation and Fragmentation of Heterogeneous Materials (Aluminum-Tungsten Composites and Aluminum-Nickel Laminates)

    Science.gov (United States)

    Chiu, Po-Hsun

    Two types of heterogeneous reactive materials, Aluminum-Tungsten composites and Aluminum-Nickel laminates were investigated. The current interest in these materials is their ability to combine the high strength and energy output under critical condition of the mechanical deformation which may include their fragmentation. Mesoscale properties of reactive materials are very important for the generation of local hot spots to ignite reactions and generate critical size of debris suitable for fast oxidation kinetics. Samples with different mesostructures (e.g., coarse vs. fine W particles, bonded vs. non-bonded Al particles, W particles vs. W wires and concentric vs. corrugated Al-Ni laminates) were prepared by Cold Isostatic Pressing, Hot Isostatic Pressing and Swaging. Several dynamic tests were utilized including Split Hopkinson Pressure Bar, Drop Weight Test, Explosively Driven Fragmentation Test, and Thick-Walled Cylinder Method. A high speed camera was used to record images of the in situ behavior of materials under dynamic loading. Pre- and post-experiment analyses and characterization were done using Optical Microscopy, Scanning Electron Microscopy, X-ray Powder Diffraction, and Laser Diffraction. The numerical simulations were conducted to monitor the in situ dynamic behavior of materials and elucidate the mesoscale mechanisms of the plastic strain accommodation under high-strain, high-strain-rate conditions in investigated heterogeneous m aterials. Several interesting results should be specifically mentioned. They include observation that the fracture and dynamic properties of the Al-W composites are sensitive to porosity of samples, particles sizes of rigid inclusions (W particles or wires), and bonding strength between Al particles in the matrix. Soft Al particles were heavily deformed between the rigid W particles/wires during dynamic tests. Three plastic strain accommodation mechanisms are observed in Al-Ni laminates. They depend on the initial

  16. Nonlinear optical properties of metal nanoparticle composites for optical applications

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Y. E-mail: takeda.yoshihiko@nims.go.jp; Kishimoto, N

    2003-05-01

    Optical absorption and nonlinear optical response were investigated for nanoparticle composites in amorphous SiO{sub 2} fabricated by negative Ta ion implantation at 60 keV. X-ray photoelectron spectroscopy was used to identify Ta and the oxide formation in the matrix. Optical absorption clearly indicated a surface plasmon peak at 2.2 eV and the peak resulted from formation of nanoparticles embedded in the matrix. The measured absorption was compared with calculated ones, evaluated by Maxwell-Garnett theory. Nonlinear absorption was measured with a pump-probe method using a femtosecond laser system. The pumping laser transiently bleached the surface plasmon band and lead to the nonlinearity. The transient response recovered in several picoseconds and behaved in terms of electron dynamics in metallic nanoparticles. The Ta nanoparticle composite is one of the promising candidates for nonlinear optical materials with good thermal stability.

  17. Uncertainty Quantification of Composite Laminate Damage with the Generalized Information Theory

    Energy Technology Data Exchange (ETDEWEB)

    J. Lucero; F. Hemez; T. Ross; K.Kline; J.Hundhausen; T. Tippetts

    2006-05-01

    This work presents a survey of five theories to assess the uncertainty of projectile impact induced damage on multi-layered carbon-epoxy composite plates. Because the types of uncertainty dealt with in this application are multiple (variability, ambiguity, and conflict) and because the data sets collected are sparse, characterizing the amount of delamination damage with probability theory alone is possible but incomplete. This motivates the exploration of methods contained within a broad Generalized Information Theory (GIT) that rely on less restrictive assumptions than probability theory. Probability, fuzzy sets, possibility, and imprecise probability (probability boxes (p-boxes) and Dempster-Shafer) are used to assess the uncertainty in composite plate damage. Furthermore, this work highlights the usefulness of each theory. The purpose of the study is not to compare directly the different GIT methods but to show that they can be deployed on a practical application and to compare the assumptions upon which these theories are based. The data sets consist of experimental measurements and finite element predictions of the amount of delamination and fiber splitting damage as multilayered composite plates are impacted by a projectile at various velocities. The physical experiments consist of using a gas gun to impact suspended plates with a projectile accelerated to prescribed velocities, then, taking ultrasound images of the resulting delamination. The nonlinear, multiple length-scale numerical simulations couple local crack propagation implemented through cohesive zone modeling to global stress-displacement finite element analysis. The assessment of damage uncertainty is performed in three steps by, first, considering the test data only; then, considering the simulation data only; finally, performing an assessment of total uncertainty where test and simulation data sets are combined. This study leads to practical recommendations for reducing the uncertainty and

  18. Nacre-like ceramic/polymer laminated composite for use in body-armor applications

    Directory of Open Access Journals (Sweden)

    Mica Grujicic

    2016-01-01

    Full Text Available Nacre is a biological material constituting the innermost layer of the shells of gastropods and bivalves. It consists of polygonal tablets of aragonite, tessellated to form individual layers and having the adjacent layers as well as the tablets within a layer bonded by a biopolymer. Due to its highly complex hierarchical microstructure, nacre possesses an outstanding combination of mechanical properties, the properties which are far superior to the ones that are predicted using the techniques such as the rule of mixture. In the present work, an attempt is made to model a nacre-like composite armor consisting of boron carbide (B4C tablets and polyurea tablet/tablet interfaces. The armor is next investigated with respect to impact by a solid right-circular-cylindrical rigid projectile, using a transient non-linear dynamics finite element analysis. The ballistic-impact response and the penetration resistance of the armor is then compared with that of the B4C monolithic armor having an identical areal density. Furthermore, the effect of various nacre microstructural features (e.g. surface profiling, micron-scale asperities, mineral bridges between the overlapping tablets lying in adjacent layers, and B4C nano-crystallinity on the ballistic-penetration resistance of the composite-armor is investigated in order to identify an optimal nacre-like composite-armor architecture having the largest penetration resistance. The results obtained clearly show that a nacre-like armor possesses a superior penetration resistance relative to its monolithic counterpart, and that the nacre microstructural features considered play a critical role in the armor penetration resistance.

  19. THE ANALYSIS OF THIN WALLED COMPOSITE LAMINATED HELICOPTER ROTOR WITH HIERARCHICAL WARPING FUNCTIONS AND FINITE ELEMENT METHOD

    Institute of Scientific and Technical Information of China (English)

    诸德超; 邓忠民; 王荇卫

    2001-01-01

    In the present paper, a series of hierarchical warping functions is developed to analyze the static and dynamic problems of thin walled composite laminated helicopter rotors composed of several layers with single closed cell. This ethod is the development and extension of the traditional constrained warping theory of thin walled metallic beams, which had been proved very successful since 1940s. The warping distribution along the perimeter of each layer is expanded into a series of successively corrective warping functions with the traditional warping function caused by free torsion or free bending as the first term, and is assumed to be piecewise linear along the thickness direction of layers. The governing equations are derived based upon the variational principle of minimum potential energy for static analysis and Rayleigh Quotient for free vibration analysis. Then the hierarchical finite element method is introduced to form a numerical algorithm. Both static and natural vibration problems of sample box beams are analyzed with the present method to show the main mechanical behavior of the thin walled composite laminated helicopter rotor.

  20. A deformation-formulated micromechanics model of the effective Young's modulus and strength of laminated composites containing local ply curvature

    Science.gov (United States)

    Lee, Jong-Won; Harris, Charles E.

    1990-01-01

    A mathematical model based on the Euler-Bermoulli beam theory is proposed for predicting the effective Young's moduli of piecewise isotropic composite laminates with local ply curvatures in the main load-carrying layers. Strains in corrugated layers, in-phase layers, and out-of-phase layers are predicted for various geometries and material configurations by assuming matrix layers as elastic foundations of different spring constants. The effective Young's moduli measured from corrugated aluminum specimens and aluminum/epoxy specimens with in-phase and out-of-phase wavy patterns coincide very well with the model predictions. Moire fringe analysis of an in-phase specimen and an out-of-phase specimen are also presented, confirming the main assumption of the model related to the elastic constraint due to the matrix layers. The present model is also compared with the experimental results and other models, including the microbuckling models, published in the literature. The results of the present study show that even a very small-scale local ply curvature produces a noticeable effect on the mechanical constitutive behavior of a laminated composite.

  1. Thickness optimization of fiber reinforced laminated composites using the discrete material optimization method

    DEFF Research Database (Denmark)

    Sørensen, Søren Nørgaard; Lund, Erik

    2012-01-01

    This work concerns a novel large-scale multi-material topology optimization method for simultaneous determination of the optimum variable integer thickness and fiber orientation throughout laminate structures with fixed outer geometries while adhering to certain manufacturing constraints. The con......This work concerns a novel large-scale multi-material topology optimization method for simultaneous determination of the optimum variable integer thickness and fiber orientation throughout laminate structures with fixed outer geometries while adhering to certain manufacturing constraints....... The conceptual combinatorial/integer problem is relaxed to a continuous problem and solved on basis of the so-called Discrete Material Optimization method, explicitly including the manufacturing constraints as linear constraints....

  2. Laser Shock Compression and Spalling of Reactive Ni-Al Laminate Composites

    Science.gov (United States)

    Wei, C. T.; Maddox, B. R.; Weihs, T. P.; Stover, A. K.; Nesterenko, V. F.; Meyers, M. A.

    2009-12-01

    Reactive laminates produced by successive rolling and consisting of alternate layers of Ni and Al (with bi-layer thicknesses of 5 and 30 μm) were investigated by subjecting them to laser shock-wave loading. The laser intensity was varied between ˜2.68×1011 W/cm2 (providing an initial estimated pressure P˜25 GPa) and ˜1.28×1013 W/cm2 (P˜333 GPa) with two distinct initial pulse durations: 3 ns and 8 ns. Hydrodynamic calculations (using commercial code HYADES) were conducted to simulate the behavior of shock-wave propagation in the laminate structures. SEM, and XRD were carried out on the samples to study the reaction initiation, and the intermetallic compounds. It was found that the thinner bilayer thickness (5 μm) laminate exhibited the most intensive localized interfacial reaction at the higher laser intensity (1.28×1013 W/cm2); the reaction products were identified as NiAl and other Al-rich intermetallic compounds. The reaction front and the formation of intermetallic compounds extend into the sample with a thinner bilayer thickness (5 μm) to a depth of about 50 μm. Increase in the duration of laser shock wave induces increased reaction, which occurs also in the thicker bilayer laminate samples (30 μm bi-layer thickness). It is demonstrated that the methodology of laser shock is well suited to investigate the threshold conditions for dynamic mechanical reaction initiation caused by high intensity laser irradiation.

  3. Evaluation of Internal Defect of Composite Laminates Using A Novel Hybrid Laser Generation/Air-Coupled Detection Ultrasonic System

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joon Hyun; Lee, Seung Joon [Pusan National University, Busan (Korea, Republic of); Byun, Joon Hyung [KIMM, Daejeon (Korea, Republic of)

    2008-02-15

    Ultrasonic C-scan technique is one of very popular techniques being used for detection of flaws in polymer matrix composite(PMC). However, the application of this technique is very limited for evaluation of defects in PMC fabricated by the automated fiber placement process. The purpose of this study is to develop a novel ultrasonic hybrid system based on nondestructive and non-contact ultrasonic techniques for evaluation of delamination in carbon/epoxy and carbon/PPS composite laminates. It was shown that the newly developed ultrasonic hybrid system based on dual air-coupled pitch-catch technique with ultrasonic scattering reflection concept could provide excellent image with higher resolution of delamination in PMC compared with the conventional pitch-catch method. It is expected that this ultrasonic hybrid technique can be applied for on-line inspection of flaws in PMC during the fabrication process

  4. Clinical evaluation on porcelain laminate veneers bonded with light-cured composite: results up to 7 years.

    Science.gov (United States)

    D'Arcangelo, Camillo; De Angelis, Francesco; Vadini, Mirco; D'Amario, Maurizio

    2012-08-01

    The purpose of this study was to evaluate the clinical performance of laminate porcelain veneers bonded with a light-cured composite. Thirty patients were restored with 119 porcelain laminate veneers. The veneers were studied for an observation time of 7 years. Marginal adaptation, marginal discoloration, secondary caries, color match, and anatomic form were clinically examined following modified United States Public Health Service (USPHS) criteria. Each restoration was also examined for cracks, fractures, and debonding. Pulp vitality was verified. In addition, plaque and gingival indexes and increase in gingival recession were recorded. Survival rate evaluating absolute failures and success rate describing relative failures were statistically determined, using both restoration and patient-related analyses. On the basis of the criteria used, most of the veneers rated Alfa. After 7 years, the results of the clinical investigation regarding marginal adaptation and marginal discoloration revealed only 2.5% and 4.2% Bravo ratings, respectively, among the 119 initially placed veneers. Using the restoration as the statistical unit, the survival rate was 97.5%, with a high estimated success probability of 0.843 after 7 years. Using the patient as the statistical unit, the survival rate was 90.0% and the estimated success probability after 7 years was 0.824. Gingival response to the veneers was all in the satisfactory range. Porcelain laminate veneers offer a predictable and successful treatment modality giving a maximum preservation of sound tooth. The preparation, cementation, and finishing procedures adopted are considered key factors for the long-term success and aesthetical result of the veneer restorations.

  5. The buckling response of symmetrically laminated composite plates having a trapezoidal planform area

    Science.gov (United States)

    Radloff, H. D., II; Hyer, M. W.; Nemeth, M. P.

    1994-08-01

    The focus of this work is the buckling response of symmetrically laminated composite plates having a planform area in the shape of an isosceles trapezoid. The loading is assumed to be inplane and applied perpendicular to the parallel ends of the plate. The tapered edges of the plate are assumed to have simply supported boundary conditions, while the parallel ends are assumed to have either simply supported or clamped boundary conditions. A semi-analytic closed-form solution based on energy principles and the Trefftz stability criterion is derived and solutions are obtained using the Rayleigh-Ritz method. Intrinsic in this solution is a simplified prebuckling analysis which approximates the inplane force resultant distributions by the forms Nx=P/W(x) and Ny=Nxy=0, where P is the applied load and W(x) is the plate width which, for the trapezoidal planform, varies linearly with the lengthwise coordinate x. The out-of-plane displacement is approximated by a double trigonometric series. This analysis is posed in terms of four nondimensional parameters representing orthotropic and anisotropic material properties, and two nondimensional parameters representing geometric properties. For comparison purposes, a number of specific plate geometry, ply orientation, and stacking sequence combinations are investigated using the general purpose finite element code ABAQUS. Comparison of buckling coefficients calculated using the semi-analytical model and the finite element model show agreement within 5 percent, in general, and within 15 percent for the worst cases. In order to verify both the finite element and semi-analytical analyses, buckling loads are measured for graphite/epoxy plates having a wide range of plate geometries and stacking sequences. Test fixtures, instrumentation system, and experimental technique are described. Experimental results for the buckling load, the buckled mode shape, and the prebuckling plate stiffness are presented and show good agreement with the

  6. Self-Healing Laminate System

    Science.gov (United States)

    Beiermann, Brett A. (Inventor); Keller, Michael W. (Inventor); White, Scott R. (Inventor); Sottos, Nancy R. (Inventor)

    2016-01-01

    A laminate material may include a first flexible layer, and a self-healing composite layer in contact with the first flexible layer. The composite layer includes an elastomer matrix, a plurality of first capsules including a polymerizer, and a corresponding activator for the polymerizer. The laminate material may self-heal when subjected to a puncture or a tear.

  7. A Nonlinear Theory for Smart Composite Structures

    Science.gov (United States)

    Chattopadhyay, Aditi

    2002-01-01

    The paper discusses the following: (1) Development of a completely coupled thermo-piezoelectric-mechanical theory for the analysis of composite shells with segmented and distributed piezoelectric sensor/actuators and shape memory alloys. The higher order displacement theory will be used to capture the transverse shear effects in anisotropic composites. The original theory will be modified to satisfy the stress continuity at ply interfaces. (2) Development of a finite element technique to implement the mathematical model. (3) Investigation of the coupled structures/controls interaction problem to study the complex trade-offs associated with the coupled problem.

  8. Nonlinear dynamic response and buckling of laminated cylindrical shells with axial shallow groove based on a semi-analytical method%半解析法求解含轴向浅槽复合材料圆柱壳的非线性动力响应及屈曲问题

    Institute of Scientific and Technical Information of China (English)

    王天霖; 唐文勇; 张圣坤

    2007-01-01

    The effect of axial shallow groove on the nonlinear dynamic response and buckling of laminated cylindrical shells subjected to radial compression loading was investigated.Based on the first-order shear deformation theory(FSDT),the nonlinear dynamic equations involving the transverse shear deformation and initial geometric imperfections were derived with the Hamilton philosophy.The axial shallow groove of the laminated composite cylindrical shell was treated as the initial geometric imperfections in the dynamic equations.A semi-analytical method of expanding displacements and loads along the circumferential direction and employing the finite difference method along the axial direction and in the time domain is used to solve the governing equations and obtain the dynamic response of the laminated shell.The B-R criterion was employed to determine the critical loads of dynamic buckhng of the shell.The effects of the parameters of the shallow groove on the dynamic response and buckling were discussed in this paper and the results show that the axial shallow grooves greatly affect the dynamic response and buckling.

  9. Fallacies of composition in nonlinear marketing models

    Science.gov (United States)

    Bischi, Gian Italo; Cerboni Baiardi, Lorenzo

    2015-01-01

    In this paper we consider some nonlinear discrete-time dynamic models proposed in the literature to represent marketing competition, and we use these models to critically discuss the statement, often made in economic literature, that identical agents behave identically and quasi-identical ones behave in a similar way. We show, through examples and some general mathematical statements, that the one-dimensional model of a representative agent, whose dynamics summarize the common behavior of identical interacting agents, may be misleading. In order to discuss these topics some simple methods for the study of local stability and bifurcations are employed, as well as numerical examples where some results taken from the literature on chaos synchronization are applied to two-dimensional marketing models that exhibit riddling, blowout and other global phenomena related to the existence of measure-theoretic attractors.

  10. THE EFFECTS OF TANNIN AND THERMAL TREATMENT ON PHYSICAL AND MECHANICAL PROPERTIES OF LAMINATED CHESTNUT WOOD COMPOSITES

    Directory of Open Access Journals (Sweden)

    Gokhan Gunduz

    2011-03-01

    Full Text Available The aim of this study was to investigate the effects of tannin and thermal treatment on physical properties such as dimensional stability and moisture content (%, as well as mechanical properties such as bending strength, modulus of elasticity, and compression strength of laminated chestnut wood composites, which are used commonly for shipboard construction in Turkey. The chestnut wood used in boat construction is usually exposed to several treatments in order to achieve better bonding performance and to remove excessive tannins. According to the results obtained, physical properties of laminated chestnut wood without tannin were better compared to samples with tannin. Oven-dry density and air-dry density were found to be higher in samples containing tannins and not exposed to thermal treatment. Moreover, the lowest value of density was observed in samples containing no tannin and exposed to thermal treatment. In terms of mechanical properties, the highest bending strength and modulus of elasticity were obtained from samples containing tannins and not exposed to heat treatment. The lowest values were found in samples without tannin exposed to heat treatment. Regarding compression strength, the maximum and minimum values were found in samples containing tannins and not exposed to heat treatment and samples without tannin and exposed to heat treatment, respectively.

  11. Evaluation of Interlaminar Stresses in Composite Laminates with a Bolt-Filled Hole Using a Linear Elastic Traction-Separation Description

    Directory of Open Access Journals (Sweden)

    Yong Cao

    2017-01-01

    Full Text Available Determination of the local interlaminar stress distribution in a laminate with a bolt-filled hole is helpful for optimal bolted joint design, due to the three-dimensional (3D nature of the stress field near the bolt hole. A new interlaminar stress distribution phenomenon induced by the bolt-head and clamp-up load, which occurs in a filled-hole composite laminate, is investigated. In order to efficiently evaluate interlaminar stresses under the complex boundary condition, a calculation strategy that using zero-thickness cohesive interface element is presented and validated. The interface element is based on a linear elastic traction-separation description. It is found that the interlaminar stress concentrations occur at the hole edge, as well as the interior of the laminate near the periphery of the bolt head. In addition, the interlaminar stresses near the periphery of the bolt head increased with an increase in the clamp-up load, and the interlaminar normal and shear stresses are not at the same circular position. Therefore, the clamp-up load cannot improve the interlaminar stress distribution in the laminate near the periphery of the bolt head, although it can reduce the magnitude of the interlaminar shear stress at the hole edge. Thus, the interlaminar stress distribution phenomena may lead to delamination initiation in the laminate near the periphery of the bolt head, and should be considered in composite bolted joint design.

  12. A parametric study of variables that affect fiber microbuckling initiation in composite laminates. I - Analyses. II - Experiments

    Science.gov (United States)

    Guynn, E. G.; Ochoa, Ozden O.; Bradley, Walter L.

    1992-01-01

    The effects of the stacking sequence (orientation of plies adjacent to the 0-deg plies), free surfaces, fiber/matrix interfacial bond strength, initial fiber waviness, resin-rich regions, and nonlinear shear constitutive behavior of the resin on the initiation of fiber microbuckling in thermoplastic composites were investigated using nonlinear geometric and nonlinear 2D finite-element analyses. Results show that reductions in the resin shear tangent modulus, large amplitudes of the initial fiber waviness, and debonds each cause increases in the localized matrix shear strains; these increases lead in turn to premature initiation of fiber microbuckling. The numerical results are compared to experimental data obtained using three thermoplastic composite material systems: (1) commercial APC-2, (2) QUADRAX Unidirectional Interlaced Tape, and AU4U/PEEK.

  13. Restoration of nonlinear motion-distorted composite frame

    Science.gov (United States)

    Yitzhaky, Yitzhak; Stern, Adrian; Kopeika, Norman S.

    2000-12-01

    A composite frame image is an interlaced composition of two sub-image odd and even fields. Such image type is common in many imaging systems that produce video sequences. When relative motion between the camera and the scene occurs during the imaging process, two types of distortion degrade the image: the edge 'staircase effect' due to the shifted appearances of the objects in successive fields, and blur due to the scene motion during each field exposure. This paper deals with restoration of composite frame images degraded by motion. In contrast to other previous works that dealt with only uniform velocity motion, here we consider a more general case of nonlinear motion. Since conventional motion identification techniques used in other works can not be employed in the case of nonlinear motion, a new method for identification of the motion from each field is used. Results of motion identification and image restoration for various motion types are presented.

  14. Interface morphology and mechanical properties of Al-Cu-Al laminated composites fabricated by explosive welding and subsequent rolling process

    Science.gov (United States)

    Hoseini-Athar, M. M.; Tolaminejad, B.

    2016-07-01

    Explosive welding is a well-known solid state method for joining similar and dissimilar materials. In the present study, tri-layered Al-Cu-Al laminated composites with different interface morphologies were fabricated by explosive welding and subsequent rolling. Effects of explosive ratio and rolling thickness reduction on the morphology of interface and mechanical properties were evaluated through optical/scanning electron microscopy, micro-hardness, tensile and tensile-shear tests. Results showed that by increasing the thickness reduction, bonding strength of specimens including straight and wavy interfaces increases. However, bonding strength of the specimens with melted layer interface decreases up to a threshold thickness reduction, then rapidly increases by raising the reduction. Hardness Values of welded specimens were higher than those of original material especially near the interface and a more uniform hardness profile was obtained after rolling process.

  15. Analysis of interlaminar fracture toughness and damage mechanisms in composite laminates reinforced with sprayed multi-walled carbon nanotubes

    KAUST Repository

    Almuhammadi, Khaled

    2014-01-01

    The present work is focused on the nanoreinforcement of prepreg based carbon fiber composite laminates to improve delamination resistance. Functionalized multi-walled carbon nanotubes (MWCNTs) were dispersed over the interface between prepreg layers through solvent spraying and the resulting mode I interlaminar fracture toughness was determined. For comparison, baseline samples with neat prepregs were also prepared. Results indicate that the introduction of functionalized MWCNTs can favorably affect the interlaminar fracture toughness, and the associated mechanisms of failure have been investigated. The manufacturing procedures and the interfacial reinforcing mechanism were explored by analyzing (i) the wettability between CNTs-solvent solution and prepreg surface, (ii) CNTs dispersion and (iii) the fractured surfaces through high resolution scanning electron microscopy and Raman mapping. © 2013 Elsevier Ltd.

  16. Tensile Failure of Unidirectional Composite Laminates%复合材料单向板的拉伸失效

    Institute of Scientific and Technical Information of China (English)

    范金娟; 刘杰; 隋晓燕

    2015-01-01

    由于复合材料断裂特征的复杂性,尚未给出所受载荷与断裂特征之间的关系,通常认为失效模式与层板的基体、纤维类型及试验温度有关。本研究通过拉伸试验、断口观察等方法研究了碳纤维与玻璃纤维增强树脂基复合材料单向板在-55、23及70℃的0°拉伸失效行为,分析了单向板0°拉伸的断裂特征、失效模式及其影响因素。结果表明:复合材料单向板的0°拉伸主要有2种失效模式,纤维基体断裂和界面失效;由于2种失效模式所占的比例不同,形成多种断口形态;失效模式、断裂特征与复合材料的拉伸强度关系不大,主要与界面的结合强度有关;试验温度、纤维、基体等对其断裂特征与失效模式的影响也主要是界面强度变化所致。%Owing to the fracture behavior complexity of composite laminates, the relationship between loads and fracture characteristics has not been obtained. It is generally believed that the failure mode of composite laminates is mainly related to the matrix, fiber and testing temperature, but in the present work, a different result was obtained. The 0° tensile failure behaviors of unidirectional composite laminates of carbon fiber reinforced polymer matrix and glass fiber reinforced polymer matrix were studied by tensile testing at -55 ℃, room temperature and 70 ℃,respectively, as well as observation of the fracture characteristics. The failure modes and influencing factors were analyzed. The results show that there exist two types of failure modes of the unidirectional composite laminates at 0° tensile test: the fracture of fiber and matrix, and the interface failure. Because of different ratio of the two failure modes, there exist different fracture characteristics. Failure modes and fracture characteristics mainly depend on the interface strength of the fiber and matrix. The effect of test temperature, fiber and matrix on the fracture

  17. 2D laminated cylinder-like BiFeO3 composites: Hydrothermal preparation, formation mechanism, and photocatalytic properties

    Science.gov (United States)

    Gao, Xiaoming; Dai, Yuan; Fu, Feng; Hua, Xiufu

    2016-12-01

    BiFeO3 perovskite with 2D laminated cylinder-like structure was prepared via a facile one-pot hydrothermal method, whose morphologies and optical properties was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion spectrum (EDS), and UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS). The photocatalytic properties of the as-prepared BiFeO3 composites were evaluated according to degrading Rhodamine B (RhB) and desulfurization under visible light irradiation, with excellent photocatalytic degradation and desulfurization activity found. Moreover, the mechanism study of active free radicals in photocatalytic activity indicates that the h+ radical in holes was mainly responsible for synergistic catalytic efficacy in photocatalytic degradation.

  18. A study of an influence of a fiber arrangement of a laminate ply on the distribution and values of stresses in the multi-layered composite material

    Directory of Open Access Journals (Sweden)

    Herbuś Krzysztof

    2017-01-01

    Full Text Available In the work are presented studies related with the influence of a fiber arrangement of a laminate ply on the distribution and values of stresses in the multi-layered composite material. For this purpose, the characteristics of the three-point bending test, according to the standard PN-EN ISO 7438, of specimens made from the composite material, where a single ply is a composition of epoxy resin and glass fibres, was mapped. The modelling process of the multi-layered composite material and its strength verification was performed in the PLM Siemens NX system. Based on the results of performed numerical studies, the relation between the value of the main angle of an arrangement of fibers in each plies of the laminate, and the distribution and values of stresses, occurring in the examined specimens has been determined.

  19. Effect of Stress on the Fire Reaction Properties of Polymer Composite Laminates

    Science.gov (United States)

    Elmughrabi, A. E.; Robinson, A. M.; Gibson, A. G.

    A small-scale loading frame was used to apply tensile and compressive stresses to glass vinyl ester and glass polyester laminates in a cone calorimeter under a heat flux of 75kW m-2. It was found, for the first time, that stress has a small but significant effect on the fire reaction properties. Increasing tensile stress increased heat release rate and smoke production, while shortening the time-to-ignition. Compressive stress had the reverse effect. This was attributed to the fact that tensile stress promotes the formation of matrix microcracks, facilitating the evolution of flammable volatiles. This hypothesis is further supported by the observation that stress has the greatest effect on the early heat and smoke release peaks, with a lower effect on the final ‘run-out’ values.

  20. Effect of load resistance on magnetoelectric properties in FeGa/BaTiO{sub 3}/FeGa laminate composites

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lei, E-mail: wl_6234@hotmail.com [Functional Materials Research Institute, Central Iron and Steel Research Institute, Beijing 100081 (China); Du Zhaofu [Functional Materials Research Institute, Central Iron and Steel Research Institute, Beijing 100081 (China); Fan Chongfei [Patent Examination Cooperation Center, State Intellectual Property Office of the People' s Republic of China, Beijing, 100190 (China); Xu Lihong; Zhang Hongping; Zhao Dongliang [Functional Materials Research Institute, Central Iron and Steel Research Institute, Beijing 100081 (China)

    2011-07-28

    Highlights: > ME composites have been fabricated by sandwiching a BaTiO3 laminate between two FeGa laminates. > The effect of electrical resistance load (RL) on the ME coupling of the laminated composite is investigated. > The ME voltage coefficient increases and tends to be saturated with the increase in RL. > The cutoff frequency and the resonance frequency reach the minimum values under open-circuit condition. > The ME output power can be adjustable by changing the RL to achieve the best active status. - Abstract: The electrical resistance load effects on an ME laminated composite of FeGa/BaTiO{sub 3}/FeGa are investigated. The results show that (i) The ME voltage coefficient increases and tends to be saturated with the increase in electrical resistance load, (ii) the cutoff frequency and the resonance frequency both shift to the lower frequency side and approach to the values under open-circuit condition with the increase in electrical resistance load, and (iii) the ME output power can be adjustable by changing the attached electrical resistance load to achieve the best active status. The present study provides the basis for the design of ME sensors and their electronic circuits.

  1. Nonlinearity management of photonic composites and observation of spatial-modulation instability due to quintic nonlinearity

    CERN Document Server

    Reyna, Albert S

    2014-01-01

    We present a procedure for nonlinearity management of metal-dielectric composites. Varying the volume fraction occupied by silver nanoparticles suspended in acetone we could cancel the refractive index related to the third-order susceptibility, $\\chi_{eff}^{(3)}$, and the nonlinear refraction behavior was due to the fifth-order susceptibility, $\\chi_{eff}^{(5)}$. Hence, in a cross-phase modulation experiment, we demonstrated for the first time the effect of spatial-modulation- instability due to $\\chi_{eff}^{(5)}$. The results are corroborated with numerical calculations based on a generalized Maxwell-Garnet model.

  2. An Approximate Solution and Master Curves for Buckling of Symmetrically Laminated Composite Cylinders

    Science.gov (United States)

    Nemeth, Michael P.

    2013-01-01

    Nondimensional linear-bifurcation buckling equations for balanced, symmetrically laminated cylinders with negligible shell-wall anisotropies and subjected to uniform axial compression loads are presented. These equations are solved exactly for the practical case of simply supported ends. Nondimensional quantities are used to characterize the buckling behavior that consist of a stiffness-weighted length-to-radius parameter, a stiffness-weighted shell-thinness parameter, a shell-wall nonhomogeneity parameter, two orthotropy parameters, and a nondimensional buckling load. Ranges for the nondimensional parameters are established that encompass a wide range of laminated-wall constructions and numerous generic plots of nondimensional buckling load versus a stiffness-weighted length-to-radius ratio are presented for various combinations of the other parameters. These plots are expected to include many practical cases of interest to designers. Additionally, these plots show how the parameter values affect the distribution and size of the festoons forming each response curve and how they affect the attenuation of each response curve to the corresponding solution for an infinitely long cylinder. To aid in preliminary design studies, approximate formulas for the nondimensional buckling load are derived, and validated against the corresponding exact solution, that give the attenuated buckling response of an infinitely long cylinder in terms of the nondimensional parameters presented herein. A relatively small number of "master curves" are identified that give a nondimensional measure of the buckling load of an infinitely long cylinder as a function of the orthotropy and wall inhomogeneity parameters. These curves reduce greatly the complexity of the design-variable space as compared to representations that use dimensional quantities as design variables. As a result of their inherent simplicity, these master curves are anticipated to be useful in the ongoing development of

  3. ELECTROSTATIC POTENTIAL OF STRONGLY NONLINEAR COMPOSITES: HOMOTOPY CONTINUATION APPROACH

    Institute of Scientific and Technical Information of China (English)

    Wei En-bo; Gu Guo-qing

    2000-01-01

    The homotopy continuation method is used to solve the electrostaticboundary-value problems of strongly nonlinear composite media, whichobey a current-field relation of J= E+ |E|2E. With the modeexpansion, the approximate analytical solutions of electric potential inhost and inclusion regions are obtained by solving a set of nonlinearordinary different equations, which are derived from the originalequations with homotopy method. As an example in dimension two, we applythe method to deal with a nonlinear cylindrical inclusion embedded in ahost. Comparing the approximate analytical solution of the potentialobtained by homotopy method with that of numerical method, we canobverse that the homotopy method is valid for solving boundary-valueproblems of weakly and strongly nonlinear media.

  4. Photoconductive and nonlinear optical properties of composites based on metallophthalocyanines

    Science.gov (United States)

    Vannikov, A. V.; Grishina, A. D.; Gorbunova, Yu. G.; Tsivadze, A. Yu.

    2015-08-01

    The photoconductive, photorefractive and nonlinear optical properties of composites from polyvinylcarbazole or aromatic polyimide containing supramolecular ensembles of (tetra-15-crown-5) - phthalocyaninato gallium, indium, - phthalocyaninateacetato yttrium, - phthalocyaninato ruthenium with axially coordinated pyrazine molecules were investigated at 633, 1030 and 1064nmusing continuous and pulsed lasers. Supramolecular ensembles (SE) were prepared through dissolution of molecular metallophthalocyanines in tetrachloroethane (TCE) and subsequent treatment via three cycles of heating to 90∘C and slow cooling to room temperature. The zscan method in femtosecond and nanosecond regimeswas used for measuring nonlinear optical properties phthalocyaninato indium and yttrium in TCE solutions and polymer films. It was established that effect of heavy metallic atom is basic factor which determines the quantum yield, photorefractive amplification of laser object beam, dielectric susceptibility of third order and nonlinear optical properties of metallophthalocyanines.

  5. Analysis of peel strength of consisting of an aluminum sheet, anodic aluminum oxide and a copper foil laminate composite

    Science.gov (United States)

    Shin, Hyeong-Won; Lee, Hyo-Soo; Jung, Seung-Boo

    2017-01-01

    Laminate composites consisting of an aluminum sheet, anodic aluminum oxide, and copper foil have been used as heat-spreader materials for high-power light-emitting diodes (LEDs). These composites are comparable to the conventional structure comprising an aluminum sheet, epoxy adhesives, and copper foil. The peel strength between the copper foil and anodic aluminum oxide should be more than 1.0 kgf/cm in order to be applied in high-power LED products. We investigated the effect of the anodic aluminum oxide morphology and heat-treatment conditions on the peel strength of the composites. We formed an anodic aluminum oxide layer on a 99.999% pure aluminum sheet using electrochemical anodization. A Ti/Cu seed layer was formed using the sputtering direct bonding copper process in order to form a copper circuit layer on the anodic aluminum oxide layer by electroplating. The developed heat spreader, composed of an aluminum layer, anodic aluminum oxide, and a copper circuit layer, showed peel strengths ranging from 1.05 to 3.45 kgf/cm, which is very suitable for high-power LED applications.

  6. Microstructure and Mechanical Properties of Accumulative Roll-Bonded AA1050A/AA5005 Laminated Metal Composites

    Directory of Open Access Journals (Sweden)

    Frank Kümmel

    2016-03-01

    Full Text Available Laminated metal composites (LMCs with alternating layers of commercial pure aluminum AA1050A and aluminum alloy AA5005 were produced by accumulative roll-bonding (ARB. In order to vary the layer thickness and the number of layer interfaces, different numbers of ARB cycles (4, 8, 10, 12, 14 and 16 were performed. The microstructure and mechanical properties were characterized in detail. Up to 8 ARB cycles, the ultrafine-grained (UFG microstructure of the layers in the LMC evolves almost equally to those in AA1050A and AA5005 mono-material sheets. However, the grain size in the composites tends to have smaller values. Nevertheless, the local mechanical properties of the individual layers in the LMCs are very similar to those of the mono-material sheets, and the macroscopic static mechanical properties of the LMCs can be calculated as the mean value of the mono-material sheets applying a linear rule of mixture. In contrast, for more than 12 ARB cycles, a homogenous microstructure was obtained where the individual layers within the composite cannot be visually separated any longer; thus, the hardness is at one constant and a high level across the whole sheet thickness. This results also in a significant higher strength in tensile testing. It was revealed that, with decreasing layer thickness, the layer interfaces become more and more dominating.

  7. Effective Dielectric Response of Nonlinear Composites of Coated Metal Inclusions

    Institute of Scientific and Technical Information of China (English)

    CHEN Guo-Qing; WU Ya-Min

    2007-01-01

    The effective dielectric response of the composites in which nondilute coated metal particles are randomly embedded in a linear host is investigated. Two types of coated particles are considered, one is that the core is nonlinear, the other is that the shell is nonlinear. We derive general expressions for the effective linear dielectric function and the effective third-order nonlinear susceptibility, and take one step forward to perform numerical calculations on the coated metal/dielectric composites. Numerical results show that the effective linear and nonlinear dielectric responses can be greatly enhanced near the surface plasmon resonant frequency. Moreover, the resonant peaks are found within a range from 0.46ωp to 0.57ωp for spherical particles and from 0.59ωp to 0.7ωp for cylindrical inclusions. In the frequency region, the resonant peak can achieve the maximum, according to an optimal structural parameter and volume fraction. The resonant frequency exhibits a redshift with the increasing structural parameter k or volume fraction f or dimensionality factor D.

  8. Geometrically Nonlinear Finite Element Analysis of a Composite Space Reflector

    Science.gov (United States)

    Lee, Kee-Joo; Leet, Sung W.; Clark, Greg; Broduer, Steve (Technical Monitor)

    2001-01-01

    Lightweight aerospace structures, such as low areal density composite space reflectors, are highly flexible and may undergo large deflection under applied loading, especially during the launch phase. Accordingly, geometrically nonlinear analysis that takes into account the effect of finite rotation may be needed to determine the deformed shape for a clearance check and the stress and strain state to ensure structural integrity. In this study, deformation of the space reflector is determined under static conditions using a geometrically nonlinear solid shell finite element model. For the solid shell element formulation, the kinematics of deformation is described by six variables that are purely vector components. Because rotational angles are not used, this approach is free of the limitations of small angle increments. This also allows easy connections between substructures and large load increments with respect to the conventional shell formulation using rotational parameters. Geometrically nonlinear analyses were carried out for three cases of static point loads applied at selected points. A chart shows results for a case when the load is applied at the center point of the reflector dish. The computed results capture the nonlinear behavior of the composite reflector as the applied load increases. Also, they are in good agreement with the data obtained by experiments.

  9. Quantitative Damage Detection and Sparse Sensor Array Optimization of Carbon Fiber Reinforced Resin Composite Laminates for Wind Turbine Blade Structural Health Monitoring

    Science.gov (United States)

    Li, Xiang; Yang, Zhibo; Chen, Xuefeng

    2014-01-01

    The active structural health monitoring (SHM) approach for the complex composite laminate structures of wind turbine blades (WTBs), addresses the important and complicated problem of signal noise. After illustrating the wind energy industry's development perspectives and its crucial requirement for SHM, an improved redundant second generation wavelet transform (IRSGWT) pre-processing algorithm based on neighboring coefficients is introduced for feeble signal denoising. The method can avoid the drawbacks of conventional wavelet methods that lose information in transforms and the shortcomings of redundant second generation wavelet (RSGWT) denoising that can lead to error propagation. For large scale WTB composites, how to minimize the number of sensors while ensuring accuracy is also a key issue. A sparse sensor array optimization of composites for WTB applications is proposed that can reduce the number of transducers that must be used. Compared to a full sixteen transducer array, the optimized eight transducer configuration displays better accuracy in identifying the correct position of simulated damage (mass of load) on composite laminates with anisotropic characteristics than a non-optimized array. It can help to guarantee more flexible and qualified monitoring of the areas that more frequently suffer damage. The proposed methods are verified experimentally on specimens of carbon fiber reinforced resin composite laminates. PMID:24763210

  10. Quantitative Damage Detection and Sparse Sensor Array Optimization of Carbon Fiber Reinforced Resin Composite Laminates for Wind Turbine Blade Structural Health Monitoring

    Directory of Open Access Journals (Sweden)

    Xiang Li

    2014-04-01

    Full Text Available The active structural health monitoring (SHM approach for the complex composite laminate structures of wind turbine blades (WTBs, addresses the important and complicated problem of signal noise. After illustrating the wind energy industry’s development perspectives and its crucial requirement for SHM, an improved redundant second generation wavelet transform (IRSGWT pre-processing algorithm based on neighboring coefficients is introduced for feeble signal denoising. The method can avoid the drawbacks of conventional wavelet methods that lose information in transforms and the shortcomings of redundant second generation wavelet (RSGWT denoising that can lead to error propagation. For large scale WTB composites, how to minimize the number of sensors while ensuring accuracy is also a key issue. A sparse sensor array optimization of composites for WTB applications is proposed that can reduce the number of transducers that must be used. Compared to a full sixteen transducer array, the optimized eight transducer configuration displays better accuracy in identifying the correct position of simulated damage (mass of load on composite laminates with anisotropic characteristics than a non-optimized array. It can help to guarantee more flexible and qualified monitoring of the areas that more frequently suffer damage. The proposed methods are verified experimentally on specimens of carbon fiber reinforced resin composite laminates.

  11. Residual stresses in angleplied laminates and their effects on laminate behavior

    Science.gov (United States)

    Chamis, C. C.

    1978-01-01

    NASA Lewis Research Center research in the field of composite laminate residual stresses is reviewed and summarized. The origin of lamination residual stresses, evidence of their presence, experimental methods for measuring them, and theoretical methods for predicting them are described. Typical results are presented which show the magnitudes of residual stresses in various laminates including hybrids and superhybrids, and in other complex composite components. Results are also presented which show the effects of lamination residual stresses on laminate warpage and on laminate mechanical properties including fracture stresses. Finally, the major findings and conclusions derived therefrom are summarized.

  12. The Effect of Nylon and Polyester Peel Ply Surface Preparation on the Bond Quality of Composite Laminates

    Science.gov (United States)

    Moench, Molly K.

    The preparation of the surfaces to be bonded is critical to the success of composite bonds. Peel ply surface preparation is attractive from a manufacturing and quality assurance standpoint, but is a well known example of the extremely system-specific nature of composite bonds. This study examined the role of the surface energy, morphology, and chemistry left by peel ply removal in resulting bond quality. It also evaluated the use of contact angle surface energy measurement techniques for predicting the resulting bond quality of a prepared surface. The surfaces created by preparing three aerospace fiber-reinforced composite prepregs were compared when prepared with a nylon vs a polyester peel ply. The prepared surfaces were characterized with contact angle measurements with multiple fluids, scanning electron microscopy (SEM), and x-ray electron spectroscopy. The laminates were bonded with aerospace grade film adhesives. Bond quality was assessed via double cantilever beam testing followed by optical and scanning electron microscopy of the fracture surfaces.The division was clear between strong bonds (GIC of 600- 1000J/m2 and failure in cohesion) and weak bonds (GIC of 80-400J/m2 and failure in adhesion). All prepared laminates showed the imprint of the peel ply texture and evidence of peel ply remnants after fabric removal, either through SEM or XPS. Within an adhesive system, large amounts of SEM-visible peel ply material transfer correlated with poor bond quality and cleaner surfaces with higher bond quality. The both sides of failed weak bonds showed evidence of peel ply remnants under XPS, showing that at least some failure is occurring through the remnants. The choice of adhesive was found to be significant. AF 555 adhesive was more tolerant of peel ply contamination than MB 1515-3. Although the bond quality results varied substantially between tested combinations, the total surface energies of all prepared surfaces were very similar. Single fluid contact angle

  13. Mechanically relevant consequences of the composite laminate-like design of the abdominal wall muscles and connective tissues.

    Science.gov (United States)

    Brown, Stephen H M

    2012-05-01

    Together, three abdominal wall muscles (external oblique, internal oblique and transversus abdominis) form a tightly bound muscular sheet that has been likened to a composite-laminate structure. Previous work has demonstrated the ability of force generated by these three muscles to be passed between one another through connective tissue linkages. Muscle fibres in each muscle are obliquely oriented with respect to its neighbouring muscles. It is proposed here is that this unique morphology of the abdominal wall muscles functions, through the application of constraining forces amongst the muscles, to increase force- and stiffness-generating capabilities. This paper presents a mathematical formulation of the stress-strain relationship for a transversely isotropic fibrous composite, and establishes a strengthening and stiffening effect when stress can be transferred between the fibrous layers. Application of empirical mechanical properties to this formulation demonstrates this effect for the abdominal wall muscles and, in greater proportion, for the anterior aponeurosis of the abdominal wall. This has implications for increasing the stiffness and passive load bearing ability of the abdominal wall muscles, and has the potential to modulate the whole muscle force-length and force-velocity relationships during contraction.

  14. Interfacial layers evolution during annealing in Ti-Al multi-laminated composite processed using hot press and roll bonding

    Science.gov (United States)

    Assari, A. H.; Eghbali, B.

    2016-09-01

    Ti-Al multi-laminated composites have great potential in high strength and low weight structures. In the present study, tri-layer Ti-Al composite was synthesized by hot press bonding under 40 MPa at 570 °C for 1 h and subsequent hot roll bonding at about 450 °C. This process was conducted in two accumulative passes to 30% and to 67% thickness reduction in initial and final passes, respectively. Then, the final annealing treatments were done at 550, 600, 650, 700 and 750 °C for 2, 4 and 6 h. Investigations on microstructural evolution and thickening of interfacial layers were performed by scanning electron microscopes, energy dispersive spectrometer, X-ray diffraction and micro-hardness tests. The results showed that the thickening of diffusion layers corresponds to amount of deformation. In addition to thickening of the diffusion layers, the thickness of aluminum layers decreased and after annealing treatment at 750 °C for 6 h the aluminum layers were consumed entirely, which occurred because of the enhanced interdiffusion of Ti and Al elements. Scanning electron microscope equipped with energy dispersive spectrometer showed that the sequence of interfacial layers as Ti3Al-TiAl-TiAl2-TiAl3 which are believed to be the result of thermodynamic and kinetic of phase formation. Micro-hardness results presented the variation profile in accordance with the sequence of intermetallic phases and their different structures.

  15. A geometrically nonlinear shell element for hygrothermorheologically simple linear viscoelastic composites

    Energy Technology Data Exchange (ETDEWEB)

    HAMMERAND,DANIEL C.; KAPANIA,RAKESH K.

    2000-05-01

    A triangular flat shell element for large deformation analysis of linear viscoelastic laminated composites is presented. Hygrothermorheologically simple materials are considered for which a change in the hygrothermal environment results in a horizontal shifting of the relaxation moduli curves on a log time scale, in addition to the usual hygrothermal loads. Recurrence relations are developed and implemented for the evaluation of the viscoelastic memory loads. The nonlinear deformation process is computed using an incremental/iterative approach with the Newton-Raphson Method used to find the incremental displacements in each step. The presented numerical examples consider the large deformation and stability of linear viscoelastic structures under deformation-independent mechanical loads, deformation-dependent pressure loads, and thermal loads. Unlike elastic structures that have a single critical load value associated with a given snapping of buckling instability phenomenon, viscoelastic structures will usually exhibit a particular instability for a range of applied loads over a range of critical times. Both creep buckling and snap-through examples are presented here. In some cases, viscoelastic results are also obtained using the quasielastic method in which load-history effects are ignored, and time-varying viscoelastic properties are simply used in a series of elastic problems. The presented numerical examples demonstrate the capability and accuracy of the formulation.

  16. Predicting the Nonlinear Response and Failure of Composite Laminates: Correlation With Experimental Results

    Science.gov (United States)

    2004-06-01

    orientation due to large deformation. 2.13. Loading case 13: stress–strain curves of (y:x=1:0) for [0/+45/45/90]s AS4 graphite/3501- 6 epoxy. A comparison of...GEORGETOWN PIKE MCLEAN VA 22101 1 USDOT FEDERAL RAILROAD M FATEH RDV 31 WASHINGTON DC 20590 3 CYTEC FIBERITE R DUNNE D KOHLI ...ORGANIZATION COPIES ORGANIZATION 1 ROM DEVELOPMENT CORP R O MEARA 136 SWINEBURNE ROW BRICK MARKET PLACE NEWPORT RI 02840 2 TEXTRON

  17. Experimental Investigation on Laminated Composite Leaf springs Subjected to Cyclic Loading

    OpenAIRE

    Rajesh, S.; G.B.Bhaskar

    2014-01-01

    An automobile industry have an interest in replacement of conventional leaf spring with composite leaf spring to get better performance with less weight. This paper deals with by replacing the conventional leaf spring with composite leaf spring. The dimensions of an existing conventional steel leaf spring of a light commercial vehicle were taken to fabricate the special die which is further used to manufacture the composite leaf spring. A single leaf with constant cross sectional area similar...

  18. In-situ fatigue life prognosis for composite laminates based on stiffness degradation

    Data.gov (United States)

    National Aeronautics and Space Administration — In this paper, a real-time composite fatigue life prognosis framework is proposed. The proposed methodology combines Bayesian inference, piezoelectric sensor...

  19. Ultrasonic Approach of Rayleigh Pitch-Catch Contact Ultrasound Waves on CFRP Laminated Composites

    Institute of Scientific and Technical Information of China (English)

    In-Young Yang; Kwang-Hee Im; Uk Heo; David K Hsu; Je-Woong Park; Hak-Joon Kim; Sung-Jin Song

    2008-01-01

    CFRP (carbon fiber reinforced plastics) composite materials have wide applicability because of their inherent design flexibility and improved material properties. However, impacted composite structures have 50%-75% less strength than undamaged structures. In this work, a CFRP composite material was nondestructively characterized in order to ensure product quality and structural integrity of CFRP and one-sided pitch-catch technique was developed to measure impacted-damaged area by using an automated-data acquisition system in an immersion tank. A pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave under defect conditions in the composite.

  20. The physical characteristics of resin composite-calcium silicate interface as part of a layered/laminate adhesive restoration.

    Science.gov (United States)

    Hashem, Danya F; Foxton, Richard; Manoharan, Andiappan; Watson, Timothy F; Banerjee, Avijit

    2014-03-01

    To compare in-vitro micro-shear bond strengths (μSBS) of resin composite to calcium silicate cement (Biodentine™) vs. glass ionomer cement vs. resin modified glass ionomer cement (RM-GIC) using an adhesive in self-etch (SE)/total etch (TE) mode after aging three substrates and bond and characterizing their failure modes. Resin composite was SE/TE bonded to 920 standardized disks of Biodentine™, GIC & RM-GIC. Dividing samples into two groups, the first underwent early (t=0min, 5min, 20min, 24h) or delayed (t=2wk, 1 month, 3 months, 6 months) substrate aging before bonding and μSBS (t=24h) testing. In the second, adhesive was applied after either early (t=5min) or delayed (t=2wk) substrate aging and then tested after bond aging (t=2wk, 1 month, 3 months, 6 months). The failure modes were identified using stereomicroscope. SEM images of selected samples were analyzed. No significant differences were observed between (SE)/(TE) bonding modes (P=0.42). With substrate aging, a significant reduction in μSBS occurred between early and delayed time intervals for Biodentine™ (P=0.001), but none for the GIC/RM-GIC (P=0.465, P=0.512 respectively). With bond aging, there was no significant difference between time intervals for all groups, except at 6 months for the GIC (PBiodentine™ is a weak restorative material in its early setting phase. Placing the overlying resin composite as part of the laminate/layered definitive restoration is best delayed for >2wk to allow sufficient intrinsic maturation to withstand contraction forces from the resin composite. A total-etch or self-etch adhesive may be used. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. Microstructured Optical Fiber Sensors Embedded in a Laminate Composite for Smart Material Applications

    Directory of Open Access Journals (Sweden)

    Hugo Thienpont

    2011-02-01

    Full Text Available Fiber Bragg gratings written in highly birefringent microstructured optical fiber with a dedicated design are embedded in a composite fiber-reinforced polymer. The Bragg peak wavelength shifts are measured under controlled axial and transversal strain and during thermal cycling of the composite sample. We obtain a sensitivity to transversal strain that exceeds values reported earlier in literature by one order of magnitude. Our results evidence the relevance of using microstructured optical fibers for structural integrity monitoring of composite material structures.

  2. Studies on effect of pre-crack length variation on Inter-laminar fracture toughness of a Glass Epoxy laminated composite

    Science.gov (United States)

    Huddhar, Arun; Desai, Abilash; Sharanaprabhu, C. M.; Kudari, Shashidhar K.; Shivakumar Gouda, P. S.

    2016-09-01

    Laminates of fiber reinforced polymer composites are good in in-plane properties and inherently weak in through thickness direction. To address this through thickness properties, the inter-laminar fracture toughness (GIc and GIIc) of a unidirectional (UD) Glass epoxy composite laminates were subjected to Mode-I and Mode-II loadings. Experiments were conducted using Double cantilever beam (DCB) and End notch flexure (ENF) specimens with varying pre-crack lengths. Mode I energy release rate (GIc) were also evaluated with modified beam and modified compliance theories. The experimental results reveal that, GIc fracture toughness increases with increasing in pre-crack length, where as in GIIc the effect of increase in pre-crack length exhibits reduced fracture toughness.

  3. Converse magnetoelectric effect in laminated composite of Metglas and Pb(Zr,TiO3 with screen-printed interdigitated electrodes

    Directory of Open Access Journals (Sweden)

    Yuan Zhang

    2014-06-01

    Full Text Available In this study, we investigate the converse magnetoelectric (CME effect in a laminated composite consisting of Metglas ribbons and Pb(Zr,TiO3 (PZT plate with screen-printed interdigitated electrodes and operating in longitudinal magnetization and longitudinal polarization (L-L mode. Large CME coefficients of 0.134 G·cm/V at frequency of 1 kHz and 2.75 G·cm/V at resonance frequency of 43.5 kHz under a small bias magnetic field of 7 Oe are achieved. The large CME effect can be attributed to the L-L mode and low mechanical loss of the Metglas/PZT laminated composite.

  4. Design and evaluation of low-cost laminated wood composite blades for intermediate size wind turbines: Blade design, fabrication concept, and cost analysis

    Science.gov (United States)

    Lieblein, S.; Gaugeon, M.; Thomas, G.; Zueck, M.

    1982-11-01

    As part of a program to reduce wind turbine costs, an evaluation was conducted of a laminated wood composite blade for the Mod-OA 200 kW wind turbine. The effort included the design and fabrication concept for the blade, together with cost and load analyses. The blade structure is composed of laminated Douglas fir veneers for the primary spar and nose sections, and honeycomb cored plywood panels for the trailing edges sections. The attachment of the wood blade to the rotor hub was through load takeoff studs bonded into the blade root. Tests were conducted on specimens of the key structural components to verify the feasibility of the concept. It is concluded that the proposed wood composite blade design and fabrication concept is suitable for Mod-OA size turbines (125-ft diameter rotor) at a cost that is very competitive with other methods of manufacture.

  5. Analysis of linear elasticity and non-linearity due to plasticity and material damage in woven and biaxial braided composites

    Science.gov (United States)

    Goyal, Deepak

    Textile composites have a wide variety of applications in the aerospace, sports, automobile, marine and medical industries. Due to the availability of a variety of textile architectures and numerous parameters associated with each, optimal design through extensive experimental testing is not practical. Predictive tools are needed to perform virtual experiments of various options. The focus of this research is to develop a better understanding of linear elastic response, plasticity and material damage induced nonlinear behavior and mechanics of load flow in textile composites. Textile composites exhibit multiple scales of complexity. The various textile behaviors are analyzed using a two-scale finite element modeling. A framework to allow use of a wide variety of damage initiation and growth models is proposed. Plasticity induced non-linear behavior of 2x2 braided composites is investigated using a modeling approach based on Hill's yield function for orthotropic materials. The mechanics of load flow in textile composites is demonstrated using special non-standard postprocessing techniques that not only highlight the important details, but also transform the extensive amount of output data into comprehensible modes of behavior. The investigations show that the damage models differ from each other in terms of amount of degradation as well as the properties to be degraded under a particular failure mode. When compared with experimental data, predictions of some models match well for glass/epoxy composite whereas other's match well for carbon/epoxy composites. However, all the models predicted very similar response when damage factors were made similar, which shows that the magnitude of damage factors are very important. Full 3D as well as equivalent tape laminate predictions lie within the range of the experimental data for a wide variety of braided composites with different material systems, which validated the plasticity analysis. Conclusions about the effect of

  6. Mode I fatigue delamination growth in composite laminates with fibre bridging

    NARCIS (Netherlands)

    Yao, L.

    2015-01-01

    Advanced composite materials have been commonly used in aerospace engineering, because of their good mechanical properties and attractive potential for creating lightweight structures. Susceptibility to delamination is one of the most important issues in the applications of these materials. This

  7. 斜荷载冲击层合板的响应研究%Study on the dynamic response of composite laminated plates under inclined loads impact

    Institute of Scientific and Technical Information of China (English)

    胡辉; 郑敏毅; 郭源君; 孙光永

    2011-01-01

    为了分析层合板受到斜荷载冲击时的响应,基于Kirchhoff经典层合板理论从平衡微分方程出发推导层合板振动的控制微分方程,利用模态叠加原理求解层合板振动控制微分方程得到层合板的位移、速度和加速度的响应.给出算例,分析了冲击力的大小、冲击的角度、板的尺寸等参数对接触面上最大剪应力的影响,并给出了剪应力在接触面上的分布情况.%The study was present, that on the dynamic response of composite laminated plates under inclined loads impact. Base on Kirchhoff classical composite laminated plated theory, the dynamic control differential equation of the composite laminated plates was established by the equilibrium differential equation. The dynamic response values relate to the structure displacement, speed and acceleration are obtained by using modal superposition methods to solve the dynamic control differential equation of the composite laminated plates. An example was given to show that the impact force, the angle of inclined loads and the length of the plate affect the maximal shearing stress of the contact surface. The distribution of the shearing stress of the contact surface is given.

  8. The usage of optical fibers for damage detection in ballistic protection composite laminates

    Directory of Open Access Journals (Sweden)

    Živković Irena D.

    2006-01-01

    Full Text Available This paper describes the procedure of embedding fiber optic sensors in laminar thermoplastic composite material, as well as damage investigation after ballistic loading. Thermoplastic-reinforced composite materials were made for increased material damage resistance during ballistic loading. Damage inside the composite material was detected by observing the intensity drop of the light signal transmitted through the optical fibers. Experimental testing was carried out in order to observe and analyze the response of the material under various load conditions. Different types of Kevlar reinforced composite materials (thermoplastic, thermo reactive and thermoplastic with ceramic plate as the impact face were made. Material damage resistance during ballistic loading was investigated and compared. Specimens were tested under multiple load conditions. The opto-electronic part of the measurement system consists of two light-emitting diodes as light sources for the optical fibers, and two photo detectors for the light intensity measurement. The output signal was acquired from photo detectors by means of a data acquisition board and personal computer. The measurements showed an intensity drop of the transmitted light signal as a result of the applied loading on composite structure for all the optical fibers. All the diagrams show similar behavior of the light signal intensity. In fact, all of them may be divided into three zones: the zone of penetration of the first composite layer, the bullet traveling zone through the composite material till its final stop, and the material relaxation zone. The attenuation of the light signal intensity during impact is caused by the influence of the applied dynamic stress on the embedded optical fibers. The applied stress caused micro bending of the optical fiber, changes in the shape of the cross-section and the unequal changes of the indices of refraction of the core and cladding due to the stress-optic effect. The

  9. Machinability of drilling T700/LT-03A carbon fiber reinforced plastic (CFRP) composite laminates using candle stick drill and multi-facet drill

    Science.gov (United States)

    Wang, Cheng-Dong; Qiu, Kun-Xian; Chen, Ming; Cai, Xiao-Jiang

    2015-03-01

    Carbon Fiber Reinforced Plastic (CFRP) composite laminates are widely used in aerospace and aircraft structural components due to their superior properties. However, they are regarded as difficult-to-cut materials because of bad surface quality and low productivity. Drilling is the most common hole making process for CFRP composite laminates and drilling induced delamination damage usually occurs severely at the exit side of drilling holes, which strongly deteriorate holes quality. In this work, the candle stick drill and multi-facet drill are employed to evaluate the machinability of drilling T700/LT-03A CFRP composite laminates in terms of thrust force, delamination, holes diameter and holes surface roughness. S/N ratio is used to characterize the thrust force while an ellipse-shaped delamination model is established to quantitatively analyze the delamination. The best combination of drilling parameters are determined by full consideration of S/N ratios of thrust force and the delamination. The results indicate that candle stick drill will induce the unexpected ellipse-shaped delamination even at its best drilling parameters of spindle speed of 10,000 rpm and feed rate of 0.004 mm/tooth. However, the multi-facet drill cutting at the relative lower feed rate of 0.004 mm/tooth and lower spindle speed of 6000 rpm can effectively prevent the delamination. Comprehensively, holes quality obtained by multi-facet drill is much more superior to those obtained by candle stick drill.

  10. Effects of Processing Parameters on the Forming Quality of C-Shaped Thermosetting Composite Laminates in Hot Diaphragm Forming Process

    Science.gov (United States)

    Bian, X. X.; Gu, Y. Z.; Sun, J.; Li, M.; Liu, W. P.; Zhang, Z. G.

    2013-10-01

    In this study, the effects of processing temperature and vacuum applying rate on the forming quality of C-shaped carbon fiber reinforced epoxy resin matrix composite laminates during hot diaphragm forming process were investigated. C-shaped prepreg preforms were produced using a home-made hot diaphragm forming equipment. The thickness variations of the preforms and the manufacturing defects after diaphragm forming process, including fiber wrinkling and voids, were evaluated to understand the forming mechanism. Furthermore, both interlaminar slipping friction and compaction behavior of the prepreg stacks were experimentally analyzed for showing the importance of the processing parameters. In addition, autoclave processing was used to cure the C-shaped preforms to investigate the changes of the defects before and after cure process. The results show that the C-shaped prepreg preforms with good forming quality can be achieved through increasing processing temperature and reducing vacuum applying rate, which obviously promote prepreg interlaminar slipping process. The process temperature and forming rate in hot diaphragm forming process strongly influence prepreg interply frictional force, and the maximum interlaminar frictional force can be taken as a key parameter for processing parameter optimization. Autoclave process is effective in eliminating voids in the preforms and can alleviate fiber wrinkles to a certain extent.

  11. A variety of microstructures in Mg/Cu super-laminate composites caused by competitive reactions during hydrogenation

    Science.gov (United States)

    Tanaka, K.; Shibata, K.; Nishida, Y.; Kurumatani, K.; Kondo, R.; Kikuchi, S.; Takeshita, H. T.

    2015-04-01

    A variety of microstructures in Mg/Cu super-laminate composites (SLCs) caused by competitive reactions during hydrogenation has been shown experimentally. Two types of MgCu2 structures, three-dimensional (3-D) network and layer, were observed after initial hydrogenation of Mg/Cu SLCs under the conditions of 573K, 86.4ks in H2 of 3-3MPa. It was proposed that Mg/Cu SLCs could be hydrogenated by two kinds of processes. The one is alloying Mg with Cu to form Mg2Cu followed by hydrogenation of Mg2Cu, leading to the formation of 3-D network of MgCu2. The other is hydrogenation of Mg followed by the reaction of MgH2 to Cu, leading to the formation of layer MgCu2. SEM observations revealed that there existed Mg2Cu nano-crystals at the interface between Mg and Cu in as-rolled Mg/Cu SLCs, and layer MgCu2 at the interface between MgH2 and Cu in pellets of MgH2 powder and Cu powder heated under the conditions of 673K, 86.4ks in H2 of 8.0 MPa. The existence of Mg2Cu nano-crystals enables alloying Mg with Cu at low temperatures (<473K).

  12. Fast and robust Matlab-based finite element model used in the layup optimization of composite laminates

    Science.gov (United States)

    Şerban, A.

    2016-08-01

    The layup optimization of the laminated composites is a very complex topic which involves a convoluted solution space usually explored using heuristic computational techniques. Due to the solution space complexity a lot of layup configurations are evaluated during the optimization process. This fact leads to the mandatory requirement that the configuration evaluation should be fast enough to ensure the convergence of the optimization procedure without sacrificing the accuracy. In this work, we propose a robust, accurate and very fast finite element model based on the first-order shear deformation theory (FSDT). The model is structured in three main parts: preprocessing, processing and post processing. The main strategy is to transfer as much as possible operations in the preprocessing phase which is executed only once and to subsequently reuse the results in the processing and post processing phases which are executed for each layup configuration. Using this strategy, the execution time of the processing and post processing phases is drastically reduced and almost consists of regenerating and solving the global linear system - more that 95%. The proposed procedure is relatively easy to implement in Matlab which holds a very powerful linear system solver for sparse matrices. Also, the accuracy of the model was demonstrated by comparison with Ansys and with some closed form solutions.

  13. Experimental Investigation on Laminated Composite Leaf springs Subjected to Cyclic Loading

    Directory of Open Access Journals (Sweden)

    S.Rajesh

    2014-03-01

    Full Text Available An automobile industry have an interest in replacement of conventional leaf spring with composite leaf spring to get better performance with less weight. This paper deals with by replacing the conventional leaf spring with composite leaf spring. The dimensions of an existing conventional steel leaf spring of a light commercial vehicle were taken to fabricate the special die which is further used to manufacture the composite leaf spring. A single leaf with constant cross sectional area similar to that of conventional leaf spring(CLS in each case such as bidirectional glass fiber reinforced plastic (GFRP, bidirectional carbon fiber reinforced plastic (CFRP, bidirectional carbon-glass reinforced plastic (C-GFRP and bidirectional glass-carbon reinforced plastic (G-CFRP were fabricated by hand layup technique and tested by universal testing machine. By using universal testing machine, load per deflection and maximum load that a leaf spring can withstand were measured. The cyclic loading with specific duration was given to the above mentioned composite leaf springs by using a laboratory designed loading set up through milling machine. From the experimented results it was observed that if conventional leaf springs are replaced by composite leaf springs an appropriate amount of weight reduction and there by improved vehicle performance could be achieved.

  14. Effect of Piezoelectric Implant on the Structural Integrity of Composite Laminates Subjected to Tensile Loads

    Science.gov (United States)

    Masmoudi, Sahir; El Mahi, Abderrahim; Turki, Saïd

    2017-02-01

    The embedment of sensors within composite structures gives the opportunity to develop smart materials for health and usage monitoring systems. This study investigates the use of acoustic emission monitoring with embedded piezoelectric sensor during mechanical tests in order to identify the effects of introducing the sensor into the composite materials. The composite specimen with and without embedded sensor were subject to tensile static and fatigue loading. The analysis and observation of AE signals show that the integration of a sensor presents advantage of the detection of the acoustic events and also show the presence of three or four types of damage during tests. The incorporation of piezoelectric sensor has a negligible influence on the mechanical properties of materials.

  15. New approximation for the effective energy of nonlinear conducting composites

    Science.gov (United States)

    Gibiansky, Leonid; Torquato, Salvatore

    1998-07-01

    Approximations for the effective energy and, thus, effective conductivity of nonlinear, isotropic conducting dispersions are developed. This is accomplished by using the Ponte Castaneda variational principles [Philos. Trans. R. Soc. London Ser. A 340, 1321 (1992)] and the Torquato approximation [J. Appl. Phys. 58, 3790 (1985)] of the effective conductivity of corresponding linear composites. The results are obtained for dispersions with superconducting or insulating inclusions, and, more generally, for phases with a power-law energy. It is shown that the new approximations lie within the best available rigorous upper and lower bounds on the effective energy.

  16. Spring-back simulation of flat symmetrical laminates with angled plies manufactured through autoclave processing

    Science.gov (United States)

    Nasir, M. N. M.; Aminanda, Y.; Mezeix, L.; Seman, M. A.; Rivai, A.; Ali, K. M.

    2016-10-01

    This paper presents a non-linear finite element analysis (FEA) method to predict the spring-back deformation for composite structures manufactured using autoclave processing. It is a progression from previous accompanying study on flat unidirectional samples and the aim is to observe spring-back warpage on laminates consisting of angled (±45°) plies compared to unidirectional (0°) laminate. Three samples for each of the symmetrical laminates with angled plies [45/0]S and [45/-45]S are manufactured and the warpage form is observed. FEA model that was utilized in the previous study, along with the physical mechanisms of spring-back such as the first ply stretching and tool-part interaction mechanisms, are maintained with only changes in material orientation for the part and the tool-part interface components. Upon comparison, the data shows that the spring-back form for symmetrical laminate becomes more complex to predict.

  17. Strengthening and repair of steel-concrete composite girders using CFRP laminates

    Science.gov (United States)

    Tavakkolizadeh, Mohammadreza

    The use of advanced composite materials for rehabilitation and repair of deteriorating infrastructure has been embraced worldwide. The conventional techniques for strengthening of substandard bridges are costly, time consuming and labor intensive. A total of 38 specimens made of steel and carbon fibers were prepared and tested to investigate the possibility of galvanic corrosion. Two simulated aggressive environments and three different amounts of epoxy coating were used. Potentiodynamic polarization and galvanic corrosion tests were conducted. The results of the experiments showed the existence of galvanic corrosion however the rate of such corrosion could be decreased significantly by epoxy coating. A total of 21 specimens made of S 5 x 10 A36 steel beams were prepared and tested to determine the effectiveness of CFRP patch on fatigue life of notched beam. The results showed that not only CFRP patch tends to extend the fatigue life of a detail more than three times, but also it decreases the crack growth rate significantly. To investigate the effectiveness of the epoxy bonded CFRP sheets in repair and retrofit of composite girders, a total of six large-scale steel-concrete composite girders made of W 14 x 30 A36 steel beam and 7.5 cm. thick by 91 cm wide concrete slab were prepared and tested. Three different numbers of CFRP layers and three different damage level in Range were considered. The retrofitting test results showed that epoxy bonded CFRP Sheet increased the ultimate load carrying capacity of composite girders and the behavior can be conservatively predicted by traditional methods. The repair test results showed that epoxy bonded CFRP sheet could restore the ultimate load carrying capacity and stiffness of damaged steel-concrete composite girders. The ultimate capacity of the repaired beam was predicted by traditional methods of analysis of steel-concrete composite beams, which was fairly conservative. Guidelines and procedures for design of Steel

  18. Characterization of the Effect of Fiber Undulation on Strength and Stiffness of Composite Laminates

    Science.gov (United States)

    2015-03-01

    compliant is a flexible polyurethane prepolymer commonly known as Adiprene LF750, a toluene diisocyanate terminated polyether (Chemtura Corp...Middlebury, CT). An intermediate-modulus flexible polyurethane prepolymer , a toluene diisocyanate polytetramethylene polycaprolactone polyether known as...Middlebury, CT), was used to cure the polyurethane prepolymers . The highest stiffness matrix for making rigid matrix composites (RMCs) consisted of

  19. Examining the Relationship Between Ballistic and Structural Properties of Lightweight Thermoplastic Unidirectional Composite Laminates

    Science.gov (United States)

    2011-08-01

    Kevlar KM2® Style 705 PVB phenolic woven aramid composite was included. A developmental unidirectional thermoplastic aramid fiber, Honeywell... discovery and development of the ARL X Hybrid architecture, which consists of 1) the balance of architecture in the panel being 75% [0°/90°] and 25

  20. Mode I fatigue delamination growth in composite laminates with fibre bridging

    NARCIS (Netherlands)

    Yao, L.

    2015-01-01

    Advanced composite materials have been commonly used in aerospace engineering, because of their good mechanical properties and attractive potential for creating lightweight structures. Susceptibility to delamination is one of the most important issues in the applications of these materials. This dis