A Numerical Model of Ratcheting in Thermal Barrier Systems
Materials Research Society Symposium Proceedings
Morphological instabilities in thermally grown oxide, observed in a range of thermal barrier systems, have been simulated by developing and using a numerical code. The simulations are based on a range of phenomena and constituent properties, such as plasticity in the bond coat and growth strains in the TGO at high temperature. One of the key implications is that the incidence of reverse yielding upon reheating is a necessary condition for morphological instabilities. That is, whenever the condition for reverse yielding is satisfied during the initial cycles, the imperfection amplitude increases with thermal cycling (ratcheting). Otherwise, shakedown occurs, i.e., the imperfection amplitude stops growing.
Karlsson, A. M., and Evans, A. G., 2000, "A Numerical Model of Ratcheting in Thermal Barrier Systems," MRS Online Proceedings Library, 645.