Testing and Safety Evaluation for Lifting Machine Structure Based on Acoustic Emission Technology

In a hydropower station, the lifting machine is a key device, which is used to lift heavy parts such as turbine rotor and draw-gate. Usually, the machine has a very large scale and is heavy, and its supporting mechanism is made of metal structural section. In addition, the structures are specifically designed according to non-standard method. After using many years, the structures may develop cracks at the areas of stress concentration or weld defect, which would result in hazard to the lifting machine. Since the structures are large and complex, it is difficult to test cracks using conventional nondestructive testing technology (NDT), such as radiographic and ultrasonic testing. Thus, the paper introduces acoustic emission (AE) technology to do the testing. The AE signals are collected from the hanger of a lifting machine in hydropower station. The safety evaluation is carried out based on AE characteristic parameters. The evaluating results demonstrate that the AE method is effective.