PSI - Issue 22

Andrey Burov et al. / Procedia Structural Integrity 22 (2019) 243–250

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Author name / Structural Integrity Procedia 00 (2019) 000 – 000

Fig. 6. Stress  y stress distribution in the TC layer: (a) without and (b) considering the interfacial debonding (the regular TGO).

Fig. 7. Principal stress   distribution in the TGO layer: without (a) and (b) considering the interfacial debonding (the regular TGO).

3.3. Residual stress state for the irregular TGO shape considering the interfacial debonding

For the case of the irregular TGO, the debonding is first occurs at the middle of the TC/TGO interface caused by a pure II mode, and the damage is developed towards the peak. There are no mode I damages near the peak locations until the temperature drops to 800 0 C (or about 500 s of the cooling time, Fig 3.) From this time, the mode I crack is initiated and then grows up to about 8  m to the middle of the TC/TGO interface. The debonding parameter reaches maximum value of 0.986 indicating there is no a complete separation between the TC and TGO layers at the peak location. There is almost no damage along the TGO/BC interface, except near the peak locations where the maximum debonding parameter amount to 0.6. As well as for the case of the regular TGO, the debonding leads to the stress redistribution in the TC and TGO layers. As shown in Fig. 8, the debonding of the TC/TGO interface results in change of the stress distribution pattern and decrease of out of-plane stresses in the TC layer, especially near the peak location. At the same time, the minimum principal stresses increase (in absolute value) by more than 15% compared with simulation without considering the interfacial debonding. As expected, the BC stress distribution with and without simulation of interface failure remains practically the same due to a negligible damage at the TGO/BC interface.

Fig. 8. Stress  y stress distribution in the TC layer: without (a) and (b) considering the interfacial debonding (the irregular TGO).