Page 166 - Mechanics Analysis Composite Materials
P. 166
Chapter 4. Mechanics of a composite layer 151
where
where, Ajf are stiffness coefficients corresponding to 4 = 0. As follows from
Eqs. (4.72),
As can be seen in Eqs. (4.73), there exist the following differential relationships
between tensile and coupling stiffnesses (Verchery and Gong, 1999):
It can be directly checked that Eqs. (4.73) provide three invariant stiffness
characteristics whose forms do not depend on 4, i.e.,
(4.74)
Any linear combination of these equations is also an invariant combination of
stiffness coefficients.
The inverse form of Eqs. (4.71) can be obtained if we substitute stresses,
Eqs. (4.67) into Hooke’s law, Eqs. (4.55), and thus expressed strains - into
Eqs. (4.70). As a result, we arrive at the following particular form of Eqs. (2.48),
(2.49):
