Further, in the case of dilute suspension, that is, a single inclusion or fibre in an infinite equivalent homogeneous medium (that is, a condition leading to a low fibre volume fraction) the following relation is given

(7.281)

where  is the bulk modulus of the matrix relating hydrostatic stress to the change in volume. The bulk modulus relates the hydrostatic stress and the change in volume as

(7.282)

It should be noted from Equation (7.281) that there is no correlation with rule of mixture for transverse shear modulus.

Note: The remaining effective properties like  and  can be obtained from the relations given in Equation (7.167).