http://worldcat.org/entity/work/id/38568236

Mechanical Properties of Fibrous Composites

Relationships between the properties of fibrous composites and the properties of their constituents are evaluated. Bounds and expressions for the effective elastic moduli of materials reinforced by hollow circular fibers are derived by a variational method. Exact results are obtained for hexagonal arrays of identical fibers and approximate results for random arrays of fibers, which may have unequal cross sections. Typical numerical results are obtained for technically important elastic moduli. The tensile strength of composite materials consisting of a ductile matrix uniaxially reinforced by high strength, high stiffness fibers are analyzed. The fibers are treated as having a statistical distribution of imperfections which result in fiber failure under applied stress. The statistical accumulation of such flaws results in failure of the composite. The application of the analysis is demonstrated by using glass fiber strength data in an evaluation of glass fiber reinforced composites. Supporting experimental studies are described. These include measurements of strength and stiffness of particle reinforced matrix materials and the development of an experimental procedure for tensile testing of thin fibrous composites containing only a single layer of fibers. Microscopic observation of the latter specimens indicated random fiber fractures at loads significantly below the ultimate composite strength level.

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