Fracture mechanical damage modelling of thermal barrier coatings

Summary The problem of how to avoid damage of TBCs has been approached by calculating the energy release rate of two crack configurations under thermal loading. This has been done for the limiting cases of perfect and lacking heat transfer across the crack. Suitable grading of TBCs is a means of suppressing the tendency to delamination and damage by both decreasing the energy release rate G and increasing its critical value Gc. TBCs can be graded such that delamination cracks would be deflected into depth where Gc is sufficiently high to avoid crack propagation.