Page 197 - Plastics Engineering
P. 197
180 Mechanical Behaviour of Composites
Fig. 3.8 Dispersion of fibres in cross-section of unidirectional composite
where
The predictions from this equation are shown in Fig. 3.7.
Another alternative is the Brintrup equation which gives E2 as
(3.15)
where
EL = Em/(l - vi)
A simplistic mechanics of materials analysis of the shear modulus G12 gives
or
where the shear modulus of the fibres is the G12f but it has been written as
Gf for simplicity.
As in the case of the transverse tensile modulus, E2, the above analysis
tends to underestimate the in-plane shear modulus. Therefore, once again it
is common to resort to empirical relationships and the most popular is the
Halpin-Tsai equation
(3.16)
