Fatigue crack detection using a piezoelectric ceramic sensor

Fatigue cracks in steel bridges can lead to brittle fracture, so it is important to find them properly. Piezoelectric ceramic sensors have been identified as inexpensive, high-sensitivity sensors for detecting the fatigue crack. Piezoelectric ceramic sensors do not require a power supply for their operation, making them suitable for long-term measurements. In this study, we conducted fundamental tests on the frequency characteristics of a piezoelectric ceramic sensor and clarified that the single integral value of the output voltage of the piezoelectric ceramic sensor has a linear relationship with strain response at a frequency of 1.0 Hz or less. We then attempted to detect the initiation and propagation of fatigue cracks using the response of the single integral value of the output voltage. The results showed that it is possible to detect the initiation and propagation of fatigue cracks using the change of the response of the integral voltage. Finally, a fatigue test using a girder specimen was carried out. The results showed that it is possible to detect the initiation and propagation of fatigue cracks from a welded part using the change in the response of the integral voltage in the same manner.