3.5 ORTHOTROPIC MATERIALS

We next examine some of the practical implications of the various stiffness and compliance matrices and consider their application to laminates commonly in use. It is helpful to recognize the simplifying assumptions that can be made, or more specifically, which of the A, B, or D terms are zero. We note that

(3.47)

with components of the type [12]:

(3.48)

(3.49)

so that comments addressed to stiffnesses also apply to the compliances. We shall discuss only regular laminates, that is, ones where all plies have equal thickness. If we only have N-type loads, the strains ? _i = ? _o ^o are the same for all plies, otherwise ? _i are different for all layers when bending or M-type loads apply. The through-thickness properties are quite different from the in-plane properties, which are discussed in Section 3.9. We summarize the major simplifications that can be made to facilitate use of Equations 3.41 through 3.49 for typical laminate stacking sequences.