Weibull statistics applied to fiber failure in ceramic composites and work of fracture

Abstract

Fiber failure locations with respect to a given matrix crack are determined for single and multiple matrix cracking in ceramic composites by defining a pointwise failure probability in terms of the Weibull strength theory. The composite is assumed to be reinforced with uniaxially aligned continuous fibers with frictionally constrained interfaces. The average fiber pullout lengths after complete and partial fiber failure are given for both single and multiple matrix cracking. Previous results reported by Sutcu [( J. Mater. Sci. 23, 928 (1988)] for the work of fracture are refined, and the composite strength beyond matrix cracking is estimated for multiple matrix cracking, assuming that all matrix cracks behave in a similar manner throughout the composite volume. The frictional stress caused by bridging fibers is considered in the strength computation in order to improve the strength prediction, especially beyond the ultimate load. The predicted results are compared to experimental results on LAS-Glass/Nicalon fiber composite.