Enhanced crack sizing and life estimation for welded tubular joints under low cycle actions

This study examines the low-cycle fatigue of circular hollow section (CHS) X-joints made of S355 steels, through a combined experimental and numerical investigation, assisted by non-destructive crack sizing methods, namely the Alternating Current Potential Drop and Ultrasonic Phased Array. The comparison of the two methods reveals the discrepancy in the crack sizing, and illustrates the fatigue crack initiation and propagation in CHS joints. This study extends the Improved Modified Neuber's Rule to estimate the local energy indicator for CHS X joints. The numerical analysis implements a continuum damage mechanics method, which estimates fatigue lives of test specimens with reasonable accuracy.