Advanced probabilistic tools for the uncertainty assessment in failure and lifetime prediction of ceramic components

Reliability analysis of ceramic components under stationary or transient loading is generally performed on the basis of a Finite Element stress analysis from which the failure probability according to the multi-axial Weakest Link theory is calculated with the help of a suitable post-processing routine. We use the STAU post-processing routine and the general purpose Finite Element code ABAQUS. Due to scatter in the material parameters, the resulting failure probability is also prone to statistical uncertainties. We present a method of assessing this scatter using so-called resampling simulation methods. We obtain confidence intervals for the failure probability. For demonstration, the effect of pooling (i.e. grouping of results from different experiments by suitable scaling procedures) on numerical result and scatter of failure probability is shown for fracture of four-point-bending specimens. A more applied example deals with a ceramic component in a clutch test bench under thermo-mechanical frictional loading. For the assessment of the underlying data base uncertainties, Bayesian credibility intervals based on the posterior distribution are presented and provide advantages compared to a conventional maximum likelihood analysis.