Background

Rotating components in turbomachinery such as stationary gas turbines or aircraft engines are exposed to stresses under high cycle fatigue (HCF) during their operation, particularly when passing through resonance frequency ranges. Under these cyclic stresses, cracks can initiate and propagate at production-induced initial defects such as lack-of-fusion or keyholing in additively manufactured components. The initiation and propagation behaviour of very short cracks is of increased interest, as these can determine a large part of the service life of such components. To describe the behaviour of short cracks, an understanding of crack closure mechanisms is necessary. This work aims to investigate oxide-induced crack closure (OICC) i.e. crack closure due to the formation of an oxide layer on the crack flanks.

Work packages

• Literature research on high-temperature oxidation, crack closure (especially OICC) and methods to implement OICC in a FEM simulation.
• Integration of the found oxide layer simulation approaches into a crack growth simulation and simulation of different load scenarios.
• Comparison of the different simulation approaches for oxide growth in terms of stability, computing time and accuracy.
• Documentation and presentation of the results.