Page 251 - Mechanics Analysis Composite Materials

236 Mechanics and analysis of composite materials

(5.29)

Transverse shear stiffnesses, Eqs. (5.17) and (5.19), acquire the form

(5.30)

and

(5.3 1)

where mn = 55,56,66 and

(5.32)

5.2. Stiffnesscoefficientsof a homogeneous layer

Consider a layer whose material stiffness coefficients A,, do not depend on
coordinate z. Then

(5.33)

and Eqs. (5.28), (5.30), and (5.31) yield the following stiffness coefficients of the
layer:

B,, =A,,h, Cm,=A,, (; e>,
- -
(5.34)
Dmn=A,, 6- eh +e2), S,, =A,,h

Both Eqs. (5.30) and (5.31) give the same result for S,,. As follows from the second
of these equations, membrane-bending coupling coefficients C,, become equal to
zero if we take e = h/2, Le., if the reference plane coincides with the middle plane of
the layer shown in Fig. 5.9. In this case, Eqs. (5.5) and (5.15) acquire the following
de-coupIed form: