Vibration analysis and fatigue lifetime assessment of a stage compressor blade with crack in gas turbine
The compressor blades in gas turbines are subjected to long-term dynamic stress, and the blades sustain a certain degree of damage. This high-cycle fatigue damage of the blade accumulates to a certain extent, the crack will appear. The blade will fracture after the crack gradually expands to a certa...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
SAGE Publishing
2025-06-01
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| Series: | Advances in Mechanical Engineering |
| Online Access: | https://doi.org/10.1177/16878132251347802 |
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| Summary: | The compressor blades in gas turbines are subjected to long-term dynamic stress, and the blades sustain a certain degree of damage. This high-cycle fatigue damage of the blade accumulates to a certain extent, the crack will appear. The blade will fracture after the crack gradually expands to a certain size. A novel evaluation approach of the high-cycle fatigue life for the cracked blade is developed. This paper analyzes the influence of the different crack sizes on the vibrational characteristics and fatigue lifetime of the blade. Considering the aerodynamic and centrifugal loads, the finite-element model of the cyclic symmetric impeller structure is constructed. A time-varying aerodynamic load mapping method and a modeling approach for contact interactions at the blade root and dovetail slot are proposed for better dynamic stress calculations. The transient dynamics method is used to solve the vibration response of the blade considering Rayleigh damping, and the results are obtained and compared to the experimental results. The reasonable structural damping is selected to lay a foundation for the analysis of blade fatigue lifetime. Goodman and S-N curves are adopted to estimate the blade fatigue lifetime. The results show that the appearance of a crack leads to the reduction in the first three natural frequencies of the blade; when the crack occurs and the crack size increases, the position of the maximum dynamic stress shifts from the blade root to the two ends of the crack, and the mean dynamic stress σ m and the fatigue limit stress amplitude σ − 1 increase, the fatigue lifetime transitions from infinite life to finite life and further decreases. |
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| ISSN: | 1687-8140 |