TIME-DEPENDENT PROBABILISTIC FAILURE OF COATED COMPONENTS

A probabilistic time-dependent failure model has been developed for the failure of materials. The model is an extension of a previously developed theory for static probabilistic failure that includes fatigue and creep rupture failure. The model has been applied to coatings and ceramic matrix composities. It has been shown to predict accurately the segment size in coatings and the statistical failure locations in brittle tensile specimen. Many of the features of the model can be illustrated using one-dimensional (i.e., through thickness) analyses of layered materials. Such analyses have direct applications to coated components. The model has been incorporated in a computer program that processes output from a finite element simulation and, hence, can be applied to structural analyses, with arbitrary loading, in any number of dimensions.