Advanced evaluation of push-in data for the assessment of fiber reinforcedceramic matrix composites

Fiber reinforced ceramics are ready to be used in wide spread applications due to their unique combination of typical ceramic properties and enhanced fracture toughness. This outstanding combination is only achievable if appr opriate fiber-matrix interfaces are ascertained. The interfacial state can favourably be measured by the fiber push-in test. This method is reviewed i n this paper and further elaborated in order to derive quantitative predict ion of the composite performance from fiber-matrix interface bonding and fr iction data. The problem of overestimating the frictional forces due to the Poisson effect is overcome by means of analysing the hysteresis area from two load-unload-cycles. Significant dependence of interface friction on fib er diameter is detected as it is predicted taking into account the effect o f fiber roughness on the interface clamping stress. A statistical procedure is applied to determine the critical debond stress which is the tipper lim it to prevent brittle fiber failure.