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Study on the detection method of surface micro-crack of shaft using the Rayleigh wave
New Physics: Sae Mulli
Published online September 12, 2017;  
© 2017 New Physics: Sae Mulli.

Yun-Taek Yeom, Hak-Joon Kim, Sung-Jin Song, Sung-Duk Kwon*
Received August 28, 2017; Revised September 12, 2017; Accepted September 12, 2017.
The wind power system has higher technology and competitiveness than other alternative electric energy sources, and its demand is continuously increasing. On the other hand, in shafts for moving the direction of wind energy, the axis is twisted due to the excessive load, and the micro-cracks on surface of shafts occur that may lead to the structural damage in wind turbines. Therefore, it is essential to evaluate the micro-cracks on the surface of the shaft. In this study, a defect measurement technique for evaluating the micro-cracks of the shaft surface using Rayleigh waves has been developed. For this purpose, the Rayleigh surface waves in the ultrasonic wedge and the surface area of ​​the rotating shaft were investigated using FEM simulation, and the optimal design parameters of the ultrasonic wedge were selected. For axial specimens with artificial defects on the surface, the measurement of the Rayleigh wave signals reflected by the defects was performed in both air and water environments, and the correlation among the angle of defect, the amplitude of defect signal, and the defect size was analyzed.

September 2017, 67 (9)