Coefficient of mutual influence of first kind :

Let us define the coefficient of mutual influence for the loading in Equation (5.60) as

(5.67)

For the loading of Equation (5.60) we have

(5.68)

Thus

(5.69)

Effective in-plane transverse modulus :

The state of stress applied is

and

(5.70)

For this state of stress, we get the relation as

(5.71)

Let us define the effective in-plane transverse modulus as

(5.72)

This can be written as using the second of Equation (5.71) as

(5.73)