Strain-Gauge Method of Detecting Subcritical Fatigue Cracks in Low-Carbon Steel Welds

Abstract

Detection of subcritical fatigue cracks in low-carbon steel welds with the strain-gauge nullindicator method based on the amplitude difference and phase difference procedures was investigated. It was established that a marked growth of the difference in strain amplitudes pointed to the origin of a main crack 1 mm long near the weld. An initial increase in strain amplitude differences reveals fatigue damage much earlier in comparison with the visual crack detection. The phase difference procedure cuts down the time of fatigue damage detection in low-carbon steel welds tens of times from the visual method.