PPA Tutorial Page 1

For a unidirectional prepreg, the 1,2 axis would be parallel and transverse to the fibers, respectively. For a fabric the warp and fill directions would define the principal material system. The laminate depicted below may consist of lamina of several materials but in the present formulation each individual ply must obey linear stress-strain behavior.





			Figure 2 - Lamina Orientation For a unidirectional prepreg, the 1,2 axis would be parallel and transverse to the fibers, respectively. For a fabric the warp and fill directions would define the principal material system. The laminate depicted below may consist of lamina of several materials but in the present formulation each individual ply must obey linear stress-strain behavior.

			Figure 3 - Layer Nomenclature for Laminate In the principal material coordinate system the stiffness relation for the kth ply is given by

			The stiffness coefficients expressed in terms of the lamina engineering material properties are defined below: