ELASTIC BEHAVIOR OF MULTIPLY COATED FIBER-REINFORCED COMPOSITES

This work is devoted to the derivation of the elastic strain and stress fields in an infinite medium constituted of an n-layered transversely isotropic cylindrical inclusion, surrounded by a transversely isotropic cylindrical matrix subjected to uniform conditions at infinity. From these results, the average strain and stress are calculated in each phase and in the n-layered inclusion. These averages are used in order to estimate the overall elastic moduli of heterogeneous fibre-reinforced materials. Christensen and Lo's energy condition for the three-phase model is extended to this case and shown to be equivalent to a strain (or a stress) condition. Whereas the method yields a new estimate for the transverse shear modulus, the four other moduli are proved to be given by the coincident Hashin-Rosen bounds for the n-C.C.A. and can be derived by a recursive algorithm.