||This paper presents a unified approach to predict the overall elastic properties of
homogeneous and isotropic composite materials from the micromechanics point of view.
Within the framework of the approach, the commonly used approaches such as dilute
estimate, Voigt estimate (VE), Reuss estimate (RE), modified rule of mixture, self-
consistent estimate (SCE), Mori-Tanaka estimate (MTE) and Wakashima-Tsukamoto
estimate (WTE) are expressible in the same form solely with different parameters.
Particularly, the Voigt bound (VB) and Reuss bound (RB), as well as the Hashin-
Shtrikman bounds (HSBs), are easily obtained by properly choosing the homogeneous
comparison material. Furthermore, in light of the present approach, tighter than
Hashin-Shtrikman bounds are proposed that can also be regarded as two kinds of