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http://dx.doi.org/10.7735/ksmte.2016.25.5.386

Vibration Characteristics and Analysis of the Critical Crack Length for a Fracture in the Last Stage Blade of a Low Pressure Steam Turbine  

Youn, Hee-Chul (Department of Mechanical Engineering, Incheon National University)
Woo, Chang-Ki (Department of Mechanical Engineering, Incheon National University)
Rhee, Zhang-Kyu (Department of Mechatronics Engineering, Yuhan University)
Publication Information
Journal of the Korean Society of Manufacturing Technology Engineers / v.25, no.5, 2016 , pp. 386-392 More about this Journal
Abstract
The sizes of last stage blades (LSB) in a low-pressure steam turbine have been getting larger for the development of high-capacity power plants. They are also larger than other blades in the same system. As a result, crack propagation in an LSB is caused by the large centrifugal force, low natural frequency, and repeated turbine startups. In this study, the critical crack length for a fracture and vibration characteristics, in accordance with crack propagation, were analyzed using a finite element method to calculate the stress intensity factor (SIF) and the natural frequency that was affected by the stress-stiffening effect. It was calculated that the frequency of the third and fifth modes passed the excited harmonic resonance (5X and 10X) and the observed calculated critical crack length matched that of the real fractured surface.
Keywords
Steam turbine; Stress intensity factor; Vibration; Fatigue fracture; Last stage blade (LSB); Critical crack length;
Citations & Related Records
Times Cited By KSCI : 3  (Citation Analysis)
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