ABSTRACT
Certain materials, such as fiber reinforced composites, have a microstructure which is symmetric with respect to three mutually perpendicular planes. Consequentlly, their elastic constants are also symmetric with respect to these planes. These materials are called orthotropic. In this Appendix we prove that the stress-strain relations for orthotropic, linearly elastic materials involve only nine constants when referred to axes which are perpendicular to the planes of symmetry of their microstructure. Moreover, in this Appendix we show that the stress-strain relations for isotropic, linearly elastic materials involve only two constants.
