Fracture mechanical damage modelling of thermal barrier coatings

The problem of how to avoid damage of TBCs has been approached by calculati ng the energy release rate of two crack configurations under thermal loadin g. This has been done for the limiting cases of perfect and lacking heat tr ansfer across the crack. Suitable grading of TBCs is a means of suppressing the tendency to delamination and damage by both decreasing the energy rele ase rate G and increasing its critical value G(c). TBCs can be graded such that delamination cracks would be deflected into depth where G(c) is suffic iently high to avoid crack propagation.