Fracture mechanics analysis of an APS applied TBC
(English)Manuscript (preprint) (Other academic)
An air plasma sprayed thermal barrier coating is investigated by fracture-mechanical analysis. The virtual crack extension method is used to calculatethe energy release rate, G, and the displacements of the crack surfaces are used to split the energy release rate into mode 1 and 2 stress intensity factors, K1 and K2 . The results of the investigation are evolutions of G, K1 and K2 as functions of delamination crack length for small delamination cracks.
An approximation of a hot spot is investigated by applying an out-of-phase load at room temperature. The results show that the out-of-phase load results in a more open crack compared with only a thermal load on the TBC system. This can explain why the out-of-phase load is dangerous.
The results show that it might be possible to base a delamination life model on fracture-mechanical data of an interface crack in the top/bond coat interface. If so, it is important that the mode mixity effects on crack growth rate is included in the life model.
Thermal barrier coating, Virtual crack extension, Interface crack, Crack initiation, Life modelling
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-87826OAI: oai:DiVA.org:liu-87826DiVA: diva2:600176