STRENGTH VERSUS GAUGE LENGTH IN CERAMIC-MATRIX COMPOSITES

The strength of ceramic-matrix composites as a function of sample gaug e length is derived as a function of the composite constituent materia l properties. Within the context of a global load-sharing assumption f or how load is transferred from broken to unbroken fibers, the analysi s shows that, for samples shorter than 0.8delta(c) (where delta(c) is the characteristic slip length determining composite pullout), the com posite ultimate strength increases with decreasing gauge length. For s amples longer than 0.8delta(c), the strength is independent of gauge l ength. Implications of these results on the performance of composites with small-scale stress concentrators is briefly discussed.