Acoustic Simulation of Hydraulic Turbine Top Bolt Fatigue Crack Detection Based on DG-FEM

Abstract

The top bolt is one of the important parts of turbine, and its health condition affects the stable operation of the pumping and storage unit. In this paper, the DG-FEM method was used to simulate ultrasonic waves to detect bolt crack defects. In the experiment, the ultrasonic propagation of single thread side and double thread side was simulated respectively under the condition of center excitation and bias excitation, and the feasibility of ultrasonic detection of bolt crack was explored. In addition, the reflection wave shapes of the two days under different excites of the center and the offset were compared, and the conclusion was drawn that the offset excites were more sensitive to the detection of bolt cracks than the center excites, and the reflected wave peaks were higher, which was conducive to improving the success rate of defect detection. It is prepared for the practical application of engineering and has certain reference value.