SKM 2023 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 33: Topical Session: Fundamentals of Fracture – Amorphous Metals

MM 33.4: Talk

Wednesday, March 29, 2023, 16:30–16:45, SCH A 215

Fracture mechanics concepts in application to functionally graded coatings (FGCs) and FGC structures — •Vera Petrova and Siegfried Schmauder — IMWF, University of Stuttgart, Pfaffenwaldring 32, 70569 Stuttgart, Germany

The problem of thermal fracture of functionally graded thermal barrier coatings on a homogeneous substrate under the influence of thermo-mechanical loadings is analyzed. It is assumed that FGCs contain a pre-existing system of multiple cracks, edge and/or internal. The thermal and mechanical properties, as well as the fracture toughness of the FGC, are modeled by functions based on the rule of mixtures with a power-law coefficient as the gradation parameter. The problem is formulated using the method of singular integral equation, which are solved numerically. The following fracture characteristics are calculated: stress intensity factors, energy release rates, critical stresses and fracture angles. A series of computational experiments is carried out for FGC/homogeneous structures with typical systems of multiple cracks in the FGC at different gradation parameters and for different material combinations. It is known that the fracture resistance of a TBC can be increased by introducing dense vertical cracks in ceramic coatings; this mechanism is due to the shielding effect in these crack systems. These crack systems are studied and discussed. The goal of this study and the investigation based on the model is to find ways to improve the fracture resistance of FGC/homogeneous structures by avoiding certain critical crack systems.