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<p>The vibration-induced stress state of the vaned disc of the final stage of the K-1000-60/3000 low-pressure cylinder steam turbine under the action of a forced harmonic load from the steam flow is investigated. Forced vibrations of the vaned disk with broken cyclic symmetry, caused by the presence of local damage due to erosion wear, are considered. A computational analysis using the finite element method showed that minor damage to three blades leads to a 2–2.5-fold increase in equivalent stresses in adjacent blades compared to an undamaged system. The greatest differences are observed in high-frequency modes (2000–2450 Hz), where vibration localization occurs, and the amplitudes of equivalent stresses in the damaged blades significantly exceed the nominal values. Based on the Basquin–Manson–Coffin model, the remaining life of the blades was estimated, taking into account local stress concentrations. It was established that local damage reduces the service life of the blades by several times, whereas restorative repair significantly increases their durability. The results confirm the critical role of cyclic symmetry violation in assessing the remaining life and vibration reliability of working blades and in utilizing the obtained information in their condition monitoring systems.</p>

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Vibration-Induced Stress State of Working Blades of the Last Stage of a Powerful Steam Turbine Under Cyclic Stress Asymmetry. Part 2. Dynamic Stress State and Assessment of the Remaining Service Life

  • 期刊论文

  • 发表日期：

    2026年5月28日

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  • A. S. Olkhovskyi,
  • O. L. Derkach

摘要

The vibration-induced stress state of the vaned disc of the final stage of the K-1000-60/3000 low-pressure cylinder steam turbine under the action of a forced harmonic load from the steam flow is investigated. Forced vibrations of the vaned disk with broken cyclic symmetry, caused by the presence of local damage due to erosion wear, are considered. A computational analysis using the finite element method showed that minor damage to three blades leads to a 2–2.5-fold increase in equivalent stresses in adjacent blades compared to an undamaged system. The greatest differences are observed in high-frequency modes (2000–2450 Hz), where vibration localization occurs, and the amplitudes of equivalent stresses in the damaged blades significantly exceed the nominal values. Based on the Basquin–Manson–Coffin model, the remaining life of the blades was estimated, taking into account local stress concentrations. It was established that local damage reduces the service life of the blades by several times, whereas restorative repair significantly increases their durability. The results confirm the critical role of cyclic symmetry violation in assessing the remaining life and vibration reliability of working blades and in utilizing the obtained information in their condition monitoring systems.