Page 253 - Mechanics Analysis Composite Materials

238 Mechanics and analysis of composite materials

Finally, for an isotropic layer, we have

(5.40)

where E =E/( I - v’).

5.3. Stiffness coefficients of a laminate
Consider a general case, Le., a laminate consisting of an arbitrary number of
layers with different thicknesses hi and stiffnessesA!), (i = 1,2,3,. ..,k).Location of
an arbitrary ith layer of the laminate is specified by coordinate ti, which is the
distance from the bottom plane of the laminate to the top plane of the ith layer (see
Fig. 5.10). Assuming that material stiffness coefficients do not change within the
thickness of the layer and using piece-wise integration we can write parameter I,,,,, in
Eqs. (5.29) and (5.32) as

LX
*k

YY
to =o

Fig. 5.10. Structure of the laminate.