Unified Fatigue Life Calculation of Q460C Steel Butt-Welded Joints with Unequal Widths Considering Fatigue Crack Initiation and Stable Propagation

This study experimentally investigated the effects of the stress amplitude and the nominal maximum stress on the fatigue life of Q460C steel butt-welded joints with unequal widths. The fatigue crack initiation length, initiation life, stable propagation life, and total life of the butt-welded joints were measured. A proposed ellipsoidal fracture model was used as the criterion of crack tip cracking and fatigue crack instability propagation. Furthermore, theoretical calculations and numerical simulations were conducted to analyze fatigue crack initiation and propagation within the joints. The fatigue life of the butt-welded joint was predicted using formulas recommended by various structural design codes and a unified fatigue life calculation model that accounts for both fatigue crack initiation and stable propagation.