Page 446 - Aircraft Stuctures for Engineering Student

10.6 laminated composite structures 427

or

which gives

Rearranging this we obtain

(10.49)

The major Poisson’s ratio qt may be found by referring to the stress system of
Fig. 10.66 and the dimensions given in Fig. 10.67. The total displacement in the
transverse direction produced by ul is given by

At = YtEllt
i.e.

At = YtEllt = U,E~I~ + VfEllf
from which

Yt = vmvm + Wf (10.50)
The minor Poisson’s ratio ut] is found by referring to Fig. 10.67. The strain in the
longitudinal direction produced by the transverse stress at is given by
at ut ut
ufl- = urn- = q- (10.51)
Et Et Ef
From the last two of Eqs (10.51)
Ef
q=-u m
Em
Substituting in Eq. (10.50)

or, from Eq. (10.48)

Now substituting for urn in the first two of Eqs (10.51)
-=- Yt
ut1
Et Et
or

(10.52)