Definition of Engineering Properties in a Composite

The most important parameter that defines the anisotropy of a composite lamina is the ply-angle or the angle of the longitudinal reinforcement with respect to the laminate boundary. The ply angle ? is shown in the figure below.

You may vary the ply-angle from lamina to lamina within a range of 0 to 90⁰ . Needless to say that the 0⁰ ply is the strongest along the longitudinal direction whereas the 90⁰ ply is the weakest one.