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Micromechanics of Composite Materials Governed by Vector Constitutive LawsThe high-fidelity generalized method of cells micromechanics theory has been extended for the prediction of the effective property tensor and the corresponding local field distributions for composites whose constituents are governed by vector constitutive laws. As shown, the shear analogy, which can predict effective transverse properties, is not valid in the general three-dimensional case. Consequently, a general derivation is presented that is applicable to both continuously and discontinuously reinforced composites with arbitrary vector constitutive laws and periodic microstructures. Results are given for thermal and electric problems, effective properties and local field distributions, ordered and random microstructures, as well as complex geometries including woven composites. Comparisons of the theory's predictions are made to test data, numerical analysis, and classical expressions from the literature. Further, classical methods cannot provide the local field distributions in the composite, and it is demonstrated that, as the percolation threshold is approached, their predictions are increasingly unreliable. XXXX It has been observed that the bonding between the fibers and matrix in composite materials can be imperfect. In the context of thermal conductivity, such imperfect interfaces have been investigated in micromechanical models by Dunn and Taya (1993), Duan and Karihaloo (2007), Nan et al. (1997) and Hashin (2001). The present HFGMC micromechanical method, derived for perfectly bonded composite materials governed by vector constitutive laws, can be easily generalized to include the effects of weak bonding between the constituents. Such generalizations, in the context of the mechanical micromechanics problem, involve introduction of a traction-separation law at the fiber/matrix interface and have been presented by Aboudi (1987), Bednarcyk and Arnold (2002), Bednarcyk et al. (2004) and Aboudi et al. (2013) and will be addressed in the future.
Document ID
20170002625
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Bednarcyk, Brett A. (NASA Glenn Research Center Cleveland, OH United States)
Aboudi, Jacob (Tel Aviv University)
Arnold, Steven M. (NASA Glenn Research Center Cleveland, OH United States)
Date Acquired
March 29, 2017
Publication Date
March 1, 2017
Subject Category
Composite Materials
Report/Patent Number
E-19330
GRC-E-DAA-TN37626
NASA/TM-2017-219449
Funding Number(s)
WBS: WBS 109492.02.03.01.30.01
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
micromechanics
dielectric constant
high-fidelity generalized method of cells
electric permittivity
composite materials
modeling
thermal conductivity

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