Real-time Measurement of Ultrasonic Waves at Bolted Joints under Fatigue Testing

Abstract

The real-time measurement of the surface acoustic wave (SAW) was carried out during the fatigue testing of the bolted joints of aluminum alloy plates with a frequency of 0.001 Hz. SAW distributions in the bolted region were compared with those obtained by the synchronized measurement, in which the ultrasonic wave was generated in synchronization with a loading cycle in the fatigue testing with a frequency of 10 Hz. At different numbers of fatigue cycles, the intensity of the reflection from the fatigue crack obtained by the real-time measurement was in good agreement with that obtained by the synchronized measurement. In the real-time measurement, the reflection intensity and profile changed with the stress level in a loading cycle, which were in good agreement with those obtained by the synchronized SAW measurement. From these results, it was confirmed that the SAW distributions obtained by the synchronized measurement is coincident with ones obtained by the real-time measurement in one loading cycle, and is not influenced by the measurement conditions.

Ultrasonic waves for materials evaluation in fatigue, thermal and corrosion damage: A review

“…For both high cycle fatigue and low cycle fatigue, it has been found that plasticity occurs near the onset of the crack, due to dislocations and slippages, and this phenomenon is responsible for the appearance of non-linear terms in ultrasonic waves [26,64].…”