STATISTICAL PROPERTIES OF HYBRID COMPOSITES. PART I: RECURSION ANALYSIS.

An adaptation of the chain-of-bundles probability model for unidirectional intraply hybrid composites consisting of two types of fibers is given. Local load sharing, which is sensitive to the different elastic moduli of the fibers, is assumed for the non-failed fiber segments in each bundle. A sequence of tight upper bounds is developed for the probability distribution of strength for the hybrid. The upper bound developed with critical crack size, based upon the hybrid median strength, is essentially identical to the true probability distribution of hybrid strength. Typically there is a negative 'hybrid effect' for hybrid breaking strain, but there is a positive 'hybrid effect' for hybrid tensile strength.