Effects of reinforcement shape on the effective moduli of composites (I)

Effects of the shape of the reinforcing phase on the effective moduli of composites are examined by using the Mori-Tanaka method. The effective elastic moduli of composites consisting of an anisotropic matrix and anisotropic reinforcing phases are first formulated for both cases of alignment and uniformly distributed orientations of inclusions. Then, the influences of some typical inclusions including fibers of infinite length, flakes of infinite radius and spheroids are compared. In the case of random orientation, a reinforcing phase of flake shape yields the same maximum elastic modulus as that of fiber shape. In the case of uniformly distributed orientation, however, flakes are more effective than fibers in stiffening. Spheroids with the long axis/short axis ratio lower than 10 show a much lower stiffening effect than flakes and fibers.