Two-parameter Weibull analysis was used to predict the fracture strength and fatigue life of an SCS-6/Ti-15-3 MMC ring from coupon sample data. The fracture strength and fatigue life of the ring were assumed to be volume dependent. The predicted fracture strengths were determined in terms of maximum allowable ring internal pressure. Two methods were used. One simple method was to calculate an effective volume for an idealized ring on the basis of a theoretical solution approximating the stress distribution. The fracture strength and fatigue life of the coupon samples were then scaled to the effective volume of the ring. The other method utilized finite-element analysis to determine a more realistic stress distribution in the actual, geometrically imperfect ring. The total reliability of the ring was then determined by the product of the elemental reliabilities with coupon samples used as a gage. These approaches were compared with experimental fracture strength results. No fatigue data for the ring were available for comparison. Preliminary results indicate that Weibull analysis of coupon samples shows promise in predicting the fracture strength of metal-matrix composite structures.

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