A numerical study on the thermal expansion coefficients of fiber

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coefficients coincide to give results in the form of unique functions of the elastic
moduli.
Another consideration was made by Sideridis (1994) who developed the model of
the inhomogeneous boundary interphase. He studied the influence of the mode of
variation of boundary’s thermal expansion coefficient, elastic modulus and Poisson’s
ratio versus the polar radius between the fiber and the matrix in the representative
volume element of a unidirectional fiber composite on the overall value of the
composite thermal expansion coefficients. He also made experiments on E-glassepoxy
composites and showed that for all volume fractions the thermal expansion
values derived from his solutions are similar to both experiments and the respective
values derived from the equations of Shapery and Van Fo Fy.
An analytical and experimental investigation on thermal expansion coefficients of
unidirectional composites was carried out by Ishikava, Koyama and Kobayashi
(1978). The fiber anisotropy and temperature dependency of the constituent material
properties were considered in the formulation of the problem. The solving technique
they used was constructed by a slight modification of their previous investigation to
calculate elastic moduli of unidirectional composites. The first point of the main
purpose of the experiments was to reveal certain temperature dependent behavior of
thermal expansion coefficient’s of the constituents of carbon-epoxy composites. The
second was a comparison between the experimental and theoretical results and the
third was to estimate unknown properties of carbon fibers.
The influence of fiber type and orientation on thermal expansion coefficient of
carbon-epoxy composites was discussed by Rogers et al. (1977). Interferometric
measurements of the linear thermal expansion coefficients between approximately
90-400 K for a series of unidirectional and bidirectional specimens of epoxy resins
reinforced with carbon fibers were made. The room temperature results shoved that
linear thermal expansion coefficients of these composites are mostly influenced by
the thermal and elastic properties of the constituents and the orientation of the fibers.
At higher temperatures their results clearly showed significant changes in the