Determination of the in-situ fiber strength of CMCs by evaluating the crack resistance of notched specimens

The following study is based on a model that describes the crack resistance of a long-fiber ceramic composite material on the basis of the crack-bridg ing stress effects (bridge stress function). Since the crack resistance of such a material is substantially dependent upon the strength of the crack-b ridging fibers, this model is well-suited to quantify the in-situ fiber str ength in the material. Using this principle, the reduction of fiber strengt h of an oxide composite material after ageing in air is proven.