Fatigue life assessment and enhancement on welded structure: Review on assessment methods with case study and recent technology

Welded joints are often susceptible to fatigue cracks initiation due to the highly concentrated stress at certain locations. The stress distribution of the welded structure is primarily influenced by the weld geometry that can be considered as a governing factor in calculating the fatigue life. In this paper, the recent development on fatigue life estimation method is discussed based on the recommendations of commission XIII of the International Institute of Welding (IIW) focusing on nominal stress, hot spot and the effective notch method. A study case of cruciform fillet welded joint with thickness of 12 mm is selected due to the extensive use as welding structure. The effect of different weld profiles of the cruciform joint on the Stress Intensity Factor and the fatigue life cycle was estimated by varying the throat size using computational numerical method. Further, the recent development in the high frequency mechanical impact method (HFMI) is presented as a reliable, effective and user-friendly method for post-weld fatigue enhancement technique for welded structures.