Cross-scale modeling and elasto-plastic mechanical properties of TBC with 3D hill-like interface

• Published in: Ceramics international 2024-05, Vol.50 (9), p.15251-15260
• Main Authors: Bao, Tiannan, Ai, Yanting, Guan, Peng, Tian, Jing, Yao, Yudong, He, Jianing
• Format: Article
• Language: English
• Subjects: Cross-scale modeling method; Elasto-plastic; Master–slave model; Thermal barrier coating; Thermally grown oxide
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2024.02.001

Failure of thermal barrier coating (TBC) systems is closely related to the temperature field and stress state of their components. The lack of accurate cross-scale analysis methods has made it difficult to clarify the mechanical properties and damage mechanisms of TBC interfaces. This study proposes a cross-scale modeling method for TBC called the thermal barrier coating master–slave model (TMSM). First, the TMSM is established based on Saint-Venant's principle, thermal elastoplastic mechanics theory, and the von Mises yield criterion, and its applicability is discussed considering mesh conditions, geometric conditions, and cyclic conditions. The advantages of the TMSM are then demonstrated by comparison with the slave model. Finally, the effects of material plasticity and oxide thickness on the damage of the TBC were analysed using the TMSM. The results showed that the boundary effect can be eliminated using the slave model with an interface side length of 160 μm. The interfacial axial stress obtained by the TMSM was greater than that obtained by the slave model. The thermal mismatch stress caused by thermal material expansion at high temperatures and the residual stress caused by material plasticity at the moment of cooling are the two main causes of TBC failure. When the thickness range of the oxide layer is 2–3 μm, the oxide layer will inhibit the maximum thermal stress during thermal cycles, which is supported by the results of fatigue experiments conducted under the same condition. This study provides a new approach for the cross-scale analysis of TBC and demonstrates the positive effect of thermally grown oxide thickness on the thermal shock resistance of TBC using numerical analysis.