Hygro-Thermo-Elastic Constitutive Equation:

This is the most general formulation for the mechanical, thermal and hygral effects on stress analysis in composites. Here, we superimpose the strains due to these three effects to give us the total strain as

(3.96)

Using constitutive equation for mechanical strains, we get

(3.97)

The stresses in the composite can be given as

(3.98)

These stresses in global coordinates xyz can be written as

(3.99)

where

(3.100)