“…In this figure, the effects of the inhomogeneities on the effective Young's modulus of a three-phase composite comprising a matrix of epoxy (E 1 ¼ 2:03 GPa and m 1 ¼ 0:4), quartz-sand particles (E 2 ¼ 73:6 GPa and m 2 ¼ 0:25), and voids (E 3 ¼ 0) are plotted when considering our proposed model, the experimental data of Cohen and Ishai (1967), and the Mori-Tanaka predictions (Weng, 1984). Following the works of Cohen and Ishai (1967) and Weng (1984), the volume fractions f 2 and f 3 are related by this relation: f 2 ¼ 0:173 1 À f 3 ð Þ . Clearly, a very good agreement is obtained between our proposed micromechanical model, the Mori-Tanaka predictions, and the experimental measurements.…”