Numerical and Analytical Approaches for Calculating the Effective ThermoMechanical Properties of Three-Phase Composites (original) (raw)
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Interphase Effect on Fiber-Reinforced Polymer Composites
Composite Interfaces - COMPOS INTERFACE, 2010
A mathematical model has been developed for the prediction of elastic moduli of three-phase fiber-reinforced composite. This model considers composite materials consisting of three phases, namely, fiber, interphase and matrix, and incorporates the effect of fiber packing. In the present paper, the interphase is assumed to be a homogeneous and isotropic material. The elastic moduli E 11, E 22, G 12 and G 23 have been evaluated and damping coefficients η 11, η 22, η 12 and η 23 have been predicted by application of a correspondence principle using this developed model. The effect of interphase volume fraction on loss factors has been evaluated. Prediction of elastic moduli and loss factors has been carried out with a weak and a strong interphase. The calculated results show that the interphase volume fraction and its properties have a very significant effect on loss factor of fiber-reinforced polymer composite. Evaluation of material properties based on the finite element method is presented using representative volume element approach. Results using the developed model are in good agreement with those obtained by FEM and other methods.
Effective elastic moduli of fiber-matrix interphases in high-temperature composites
Metallurgical and Materials Transactions A, 1996
This article describes a theoretical model and an experimental method for determination of interphasial elastic moduli in high-temperature composites. The interphasial moduli are calculated from the ultrasonically measured composite moduli via inversion of multiphase micromechanical models. Explicit equations are obtained for determination of interphasial stiffnesses for an interphase model with spring boundary conditions and multiphase fiber. The results are compared with the exact multiphase representation. The method was applied to ceramic and intermetallic matrix composites reinforced with SiC SCS-6 fibers. In both composites, the fiber-matrix interphases include approximately 3-/zm-thick carbon-rich coatings on the outer surface of the SiC shell. Although the same fiber is used in both composite systems, experimental results indicate that the effective interphasial moduli in these two composite systems are very different. The interphasial moduli in intermetallic matrix composites are much greater than those in ceramic matrix composites. After taking the interphase microstructure into account, we found that the interphasial moduli measured for the intermetallic matrix composites are very close to the estimated bulk moduli of the pyrolytic carbon with SiC particle inclusions. Our analysis shows that the lower effective interphasial moduli in the reaction-bonded Si3N 4 (RBSN) ceramic matrix composites are due to imperfect contact between the interphasial carbon and the porous matrix and to thermal tension forces which slightly unclamp the interphase. Thus, measured interphase effective moduli give information on the quality of mechanical contact between fiber and matrix. Possible errors in the interphasial moduli determined are analyzed and the results show that these errors are below 10 pct. In addition, the use of the measured interphasial moduli for assessment of interphasial damage and interphase reactions is discussed.
The role of the fiber-matrix interphase on composite properties
Vacuum, 1990
A review of recent work on the subject of the effect of fiber-matrix adhesion on composite properties has shown that previous research (which has postulated a relationship between a single parameter model of adhesion e.g. chemical bonding), has not been successful. Because of the complexity of the area where the fiber and matrix come in contact a new formalism based on a fiber-matrix interphase is postulated. Results of studies are presented which show the effect of and the interrelationships between various interfacial parameters on composite properties.
Modelling of interfacial effects on the mechanical properties of fibre-reinforced composites
Composites Part A: Applied Science and Manufacturing, 1998
The implementation of an imperfect bond between the fibre and the matrix in the micromechanical model of cell assembly is achieved by two approaches. In the first one, a displacement jump at the fibre-matrix interface is introduced. The second approach replaces solely the fibre and the interphase by an equivalent medium. Our results show that the two approaches give the same estimation of effective elastic properties which describe the behaviour of the composite in its transverse plane. The combination of the tangential and normal interphase stiffness effect has been observed by loading a composite at a 45Њ off-axis. When the displacement discontinuity approach is used, the fibre-matrix interface has an important effect on failure modes generated in the composite. We have noticed that the loss of material strength is much greater as the fibre-matrix bond becomes poor. ᭧ 1998 Published by Elsevier Science Ltd. All rights reserved (Keywords: fibre-matrix interface; interphase effects; homogenized behaviour; failure modes; micromechanical models)
Composites Part A: Applied Science and Manufacturing, 2001
Composites Part A: Applied Science and Manufacturing publishes original research papers, review articles, case studies, short communications and letters from a wide variety of sources dealing with all aspects of the science and technology of composite materials, including fibrous and paniculate reinforcements in polymeric, metallic and ceramic matrices, aligned eutectics. reinforced cements and plasters, and 'natural' composites such as wood and biological materials. The range of applicable topics includes the properties, design and manufacture of reinforcing fibres and particles, fabrication and processing of composite materials and structures, including process science and modelling, microstructural characterization of composites and their constituent phases, interfaces in composites, prediction and measurement of mechanical, physical and chemical properties, and performance of composites in service. Articles are also welcomed on economic and commercial aspects of the applications of composites, design with composites and case studies. All articles published are subject to rigorous peer review and a high standard is set for both content and presentation. The Editors aim to conduct the review procedure with the minimum of delay so that prompt publication ensues.
A theoretical study of the effect of an interfacial layer on the properties of composites
Polymer Engineering and Science, 1974
A theoretical analysis using finite element methods has been applied to oriented short-fiber composites and spherical particle composites in order to predict the influence of a finite layer at the interface on mechanical properties. In this study the interfacial layer has been modeled by assuming that a layer surrounds the interface and that this layer has a modulus of elasticity different than both the fiber and the matrix. The stress distribution near the interface has been determined as a function of the elastic constants of the interface layer and the interface layer volume fraction. This analysis has also been performed for two volume fractions of fibers and two fiber length to diameter ratios. From this stress distribution, the composite modulus and toughness have been determined as a function of interface modulus. It is theoretically shown that the toughness, measured by amount of strain energy absorbed, can be maximized by controlling the interface modulus. Furthermore, recent experimental results appear to verify the theory.
The interphasial regions in interlayer fiber composites
Polymer Composites, 1991
The interaction between the fiber and matrix in a fiber-reinforced material plays an important role in determining the mechanical behavior of thc composite. An efficient technique to simultaneously improve fiber-matrix interfacial shear strength and impact behavior of the composite is to deposit a flexible interlayer onto the fiber. This results in the creation of three bulk phases, the fiber, matrix, and the interlayer and two interphasial regions. A phenomenological model that defines the variation of the fiber-interlayer interphase and that of the interlayer-matrix interphase has been developed. In the model, the elastic moduli of these regions vary continuously, so as to bridge the two bulk phases on either side of the interphase. The interaction between the bulk phases is also taken into consideration. The model has the potential for the use of dynamic mechanical analysis to obtain, relatively, adhesion/interaction parameters of different fiber-interlayer-matrix systems. These parameters can be used to determine the optimum interlayer thickness for improved toughness and good stress transfer efficiency.
Evaluation of the effective elastic properties of long fiber reinforced composites with interphases
Computational Materials Science, 2012
The present paper predicts the effective elastic properties of long fiber reinforced composites which have transversely isotropic material behavior. It is assumed that there is a periodic microstructure, which can be taken by homogenization as a representative volume element (RVE) for the composite. A three phases (fibers, matrix and interphases between fibers and matrix) RVE is applied to study the effects of the interphase on the effective elastic properties of composites. By using the periodicity boundary conditions and the average field theory, the effective elastic properties of composites are evaluated on the basis of hexagonal and square fiber arrangement. Considering the orthotropic material behavior of composites with square fiber arrangement, a rotational average procedure which leads to the transversely isotropic stiffness matrix of composites with square fiber arrangement is developed. The effective elastic properties derived from hexagonal and square fiber arrangements combining with the rotational average procedure are compared, and the discrepancies are present. Effects of the volume fraction and stiffness of the interphase on the effective elastic properties are discussed. The present results are in good agreements with other existing results.