Introduction:
           
In the previous lecture, we have introduced the laminate constitutive equation and classification of laminates. Further, we have seen the partially and fully inverted form of the constitutive equations. In this lecture we are going to see the laminate engineering constants and some numerical examples based on this.

Laminate Engineering Constants:

In this section we will develop the laminate engineering constants, similar to lamina engineering constants as we have done earlier. Here, we will consider only symmetric laminates as the extension-bending coupling is absent. We have constitutive equation from Equation. (5.28) as

For the symmetric laminate with , we get

From the first of the above equation, we can write

(5.54)

Let us define the laminate average stress  as

(5.55)

Using Equation (5.54), we get

(5.56)

The strains can be given by inverting the above equation as

(5.57)

Let us define,  as laminate compliance. Thus,

(5.58)

The expanded form of above equation is written as

(5.59)