The Numbers of Elastic Properties and Failure Parameters for Fiber Composites

It is shown that there is a coordination between the numbers of the elastic properties and the numbers of the failure criteria parameters for aligned fiber composites under certain realistic conditions. These conditions require a high degree of anisotropy appropriate to polymeric matrix composites such that failure decomposes into separate fiber dominated and matrix dominated modes. Failure criteria are given in both five parameter and four parameter forms. The five parameter failure form coordinates with the usual five elastic property form for transversely isotropic composites. The four parameter failure form coordinates with a reduced four elastic property form which is shown to be applicable as an approximation for the same typical fiber composites.