Before investigate the coefficients, a numerical study is first
performed to evaluate the sensitivity of the predicted coefficients
by using the RVE commented earlier, considering mesh refinement.
Thus, different mesh densities for the square unit cell were inves-
tigated. Three mesh densities for the unit cell were used namely a
coarse one with approximately 2000 elements, a medium one with
approximately 4000 elements, and a fine one with approximately
8000 elements. The results showed that the differences for the
effective coefficients for the medium to fine ones are of 10À4 order.
Therefore, all the results are shown only for the meshed RVE
namely medium (approximately 4000 elements).
In order to illustrate the comparison of the coefficients effective
calculated using Hashin’s, Nairn’s and present interface model,
some numerical examples are presented. The material properties
used in the calculations are listed in Table 1, which are given by
[38]. For almost all calculations, the interface volume fraction is
assumed to be equal 0.0001. For example, in Table 2, it was shown
the effective coefficients for fiber volume fraction equal 0.5, con-
sidering the two limit cases, i.e. complete separation of the inter-
face and perfect bonding. And, it is observed that the results of
the three models show convergence. Only one study was per-
formed considering different values for the interphase thickness
t i with fiber volume fraction equal 0.6 (Table 3). In this study