EXPERIMENTAL AND THEORETICAL ASSESSMENT OF THE LONGITUDINAL TENSILE-STRENGTH OF UNIDIRECTIONAL SIC-FIBER TITANIUM-MATRIX COMPOSITES/

The tensile strength of unidirectional SiC-fiber/titanium composites ( SCS-6/Ti-1100) of varying fiber volume fraction (0.15-0.35) was measur ed in the as-produced condition. Additionally, fibers were etched from the panels and tensile tested to determine their strength distributio n, interface properties were measured with fiber push-out tests, and t he tensile properties of the matrix (without fiber) were also determin ed. From the measured constituent properties, the composite strength w as predicted by using both global load-sharing (GLS and LLS) models, p redictions were compared with the measured values. The composite stren gth was lower than predicted by Curtin's GLS model, but greater than p redicted if it is assumed that the first fiber failure initiates compo site failure (i.e. severe LLS). Metallographic examination of the frac tured specimens revealed that the failure was consistent with a non-cu mulative (localized damage) failure mode, which, as suggested by previ ous theoretical and experimental studies, is promoted by matrix plasti city. (C) 1997 Elsevier Science Limited.