Strength Modeling of two-component hybrid fiber composites in case of simultaneous fiber failures

The strength of unidirectional short fiber hybrid structures and composites is strongly influenced by the length of the constituent and reinforcing elementary fibers. Based on our earlier fiber bundle-theoretical results, we have developed a simple statistical model and determined the strength of hybrid structures for elementary fibers, which simultaneously fail or debond from the environment in a brittle manner, and the dependence of the strength on the length of the elementary fibers. In the case of constant elementary fiber length, a simple analytical relation is obtained between the average tensile strength and the length of the elementary fiber. Based on these results, formulae have been developed to estimate the strength of unidirectional short hybrid fiber reinforced composites as a function of fiber length and fiber content. Practical applicability of the results has been demonstrated for basalt fiber hybrid composites taking into account fiber fragmentation, imperfect interfacial adhesion, and fiber orientation by using suitable correction factors.