Stress simulation calculation of thermal barrier coatings under thermal-mechanical coupling conditions

Abstract

Finite element simulation is one of the effective means to study the stress evolution of thermally grown oxides （TGO） at the interface of thermal barrier coatings （TBCs）， which can provide theoretical support for exploring the failure mechanism of TBCs. Advanced thermal barrier coating multifactor coupling test equipment was used to conduct thermal-mechanical coupling cycle tests and thermal cycling tests on circular tube specimens coated with TBCs， simulating engine operating conditions. Finite element modeling was conducted on TBCs containing real initial TGO morphology using finite element software ABAQUS， and the stress and deformation patterns of the coatings during tests were analyzed. The results show that without considering TGO and interface cracking， both the thermal-mechanical coupling model and the thermal cycle model exhibit an increase in Mises stress as the number of cycles increases. During the heating process， TGO is subjected to tension， while during the cooling process， TGO is compressed. The stress during the heating process is much lower than that during cooling to room temperature. After the same number of cycles， the stress values in thermal-mechanical coupling model are higher than those in the thermal cycle model. After 20， 45， 70 thermal cycles， the TGO stresses at room temperature reach 2.85， 3.65 GPa and 3.55 GPa， respectively. After the same number of thermal-mechanical coupling cycles；when cooling to room temperature，TGO stresses at the same position at room temperature reach 4.01 GPa， 5.0 GPa and 4.81 GPa， respectively. Compared with thermal cycles， under thermal coupling conditions， the TGO stress significantly increased after the same cycles when cooling to room temperature.

Keywords

• numerical simulation
• thermal barrier coating
• thermal-mechanical coupling
• finite element method
• stress