Fracture mechanics analysis of microcracks in thermally cycled thermal barrier coatings |
| |
Authors: | Y Liu C Persson S Melin |
| |
Affiliation: | (1) Division of Materials Engineering, Department of Mechanical Engineering, Lund University, SE-22100 Lund, Sweden;(2) Division of Solid Mechanics, Department of Mechanical Engineering, Lund University, SE-22100 Lund, Sweden |
| |
Abstract: | The effects from thermal shock loading on pre-existing microcracks within thermal barrier coatings (TBCs) have been investigated
through a finite element based fracture mechanical analysis. The TBC system consists of a metallic bond coat and a ceramic
top coat. The rough interface between the top and bond coats holds an alumina oxide layer. Stress concentrations at the interface
due to the interface roughness, as well as the effect of residual stresses, were accounted for. At the eventual closure between
the crack surfaces, Coulomb friction was assumed. To judge the risk of fracture from edge cracks and centrally placed cracks,
the stress intensity factors were continuously monitored during the simulation of thermal shock loading of the TBC. It was
found that fracture from edge cracks is more likely than from centrally placed cracks. It was also concluded that the propagation
of an edge crack is already initiated during the first load cycle, whereas the crack tip position of a central crack determines
whether propagation will occur. |
| |
Keywords: | central crack edge crack finite element method thermal barrier coatings |
本文献已被 SpringerLink 等数据库收录! |
|