Page 228 - Plastics Engineering

Mechanical Behaviour of Composites 21 1

Fig. 3.22 Ten ply laminate

[;;I EX =a. [ NX =a. [3
;
;
I
Then
*h
where h = full laminate thickness = 10 mm, and a = A-’ since [B] = 0.
This matrix equation gives the global strains as
Ex = 5.24 = 1.33 x eXy = 2.08 10-~

Also,
1
1
E, = -
E, = - 1 Gxy = -
all * h’ a22 - h’ a66.h
-a12 -a12
,
Vxy = - up=-
all a22
E, = 49.7 GN/m2, E, = 12.8 GN/m2, Gxy = 24 GN/m2
uXy = 1.149 U~ = 0.296

It may be seen that these values agree with those calculated in the previous
Example. To get the stresses in the global (xy) directions for the ‘f’th ply

when f = 1, f =2, f =9 and f = 10
ax = 4.5 MN/m2, a, = -11.3 MN/m2, txy = -0.28 MNlm2