Effect of changes in elastic constants on the strength of composites

Abstract

Tensor polynomial, maximum stress, and maximum strain criteria are considered in an investigation of the effect of varying elastic constants on the failure strength of composites. By expressing each criterion in the alternative stress or strain space they are made explicitly dependent on elastic constants as well as strength parameters. The significance of this result is highlighted by an example of the variation in failure envelope produced by altering the Poisson's ratio of the composite material. In particular the failure envelopes for a high strength graphite/epoxy resin (SP-286/T300) composite lamina are examined as a function of variations in the material's Poisson's ratio. The limits in the variation of the Poisson's ratio for this composite lamina are identified.