Case study: Stress Evaluation of a Compressor Disk
Location: Stage 8 compressor disk of a gas turbine
Objective: Two indications were found on a stage 8 compressor disk. Local repair was performed to machine out indications. Finite element analysis (FEA) was performed to examine the impact on the local stress levels and distributions at operating speed with the proposed modification.
Background
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Two indications were found on a stage 8 compressor disk. One indication was machined off circumferentially and the other one was repaired by local excavation.
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TTI was solicited to perform finite element analysis (FEA) to examine the impact on the local stress levels and distributions at operating speed with the proposed modification.
Summary of Analyses
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FEA simulation shows that there are local steady state stress concentrations at both locations after repair. Nevertheless, the increase of stress does not seem excessive.
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Low cycle fatigue (LCF) should not be a concern with such moderate stress levels. The repair strategy appears to be promising for long term reliability of the modified disk.