Flexural Engineering Constants of a Laminate:

For a symmetric laminate, we have . Hence, from the second of Eq. (5.28) we write

(5.87)

Let us define the laminate average moments as

The inverse of this equation is written as

Writing this in expanded form

(5.88)

Now the applied resultant moments be

(5.89)

Effective Flexural Longitudinal Young’s Modulus :

(5.90)

Thus, using Equation (5.87) and Equation (5.88),

(5.91)

Flexural Poisson’s Ratio :

Let us define flexural Poisson’s ratio as

(5.92)

Thus, from Equation (5. 87) and Equation (5.88),

(5.93)

In a similar way, one can show that the other flexural moduli can be given by following relations.

(5.94)

Further, it can be shown that the reciprocal relation also holds true for flexural Poisson’s ratios as

(5.95)