Abstract

Advanced repair techniques intended for jet engine parts are continuously under development and improvement. Patching is a high-tech approach towards reduced scrap rates and an extended life of high pressure compressor blisks.

In this work, we contribute to the structural design of patches for compressor blisks with improved high cycle fatigue behaviour. A fully parameterised patch model is developed, which allows the accurate description of the patch geometry. High cycle fatigue is assessed for welding seam positions specified by the patch model. On the basis of this automated process, a multi-objective optimisation is carried out. The fatigue strength and the length of the welding seam are defined as conflicting targets. Pareto-optimal solutions are calculated using a generalised pattern search algorithm. The engineer’s decision for a specific patch geometry can thus be made based on the optimisation results. The application of the new approach to a compressor blisk demonstrates the influence of vibration modes on fatigue strength. We identify sets of optimal suited patch geometries in accordance to the specified damage pattern.

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