TY  - EJOU
AU  - Wang, Zhen-Ming 
AU  - Li, Heng 
AU  - Dong, Li-Tong 
AU  - Chang, Kyong-Ho 
AU  - Lee, Chin-Hyung 

TI  - Study on the Influence of Misalignment Size on Fatigue Life and Crack Initiation of Butt-Welded Structures
T2  - Structural Durability \& Health Monitoring

PY  - 
VL  - 
IS  - 
SN  - 1930-2991

AB  - Butt welding technology is widely used in critical fields such as architecture and civil engineering, pipeline and energy transmission, pressure vessels, shipbuilding and marine engineering, rail transit, and aerospace. However, defects such as weld misalignment are common during fabrication, and systematic research on the influence of misalignment magnitude on the fatigue life of welded structures remains inadequate. To clarify this influence mechanism, this study employed a 3D fatigue finite element (FE) method to simulate and compare three butt-welded specimens (one without misalignment and two with different misalignments). First, a 3D non-steady heat transfer analysis was conducted to simulate the welding process and obtain the corresponding thermal history. Subsequently, based on the thermal data, thermal elastic-plastic analysis was carried out to calculate the residual stress fields and deformation distributions of each configuration. The analysis results indicated that weld misalignment exerted a negligible influence on residual stress. In the fatigue assessment phase, the residual stresses and deformations obtained from the thermal elastic-plastic analysis were introduced as initial conditions to systematically evaluate the fatigue life and predict the initial crack initiation sites. Finally, under the same displacement loading conditions, a comparative analysis of the S-N curve results clearly demonstrated the detrimental effect of weld misalignment on the fatigue life of butt-welded structures. As the misalignment magnitude increased, the fatigue life decreased significantly, while exerting no influence on initial crack initiation sites. Under five identical cyclic loading conditions, the fatigue life reduction rates are 30.7%, 48.7%, 62.6%, 65.5%, and 70.1% for the 1 mm misalignment specimens, and 49.3%, 53.2%, 75.5%, 81.2%, and 85.2% for the 2 mm misalignment specimens. Furthermore, the validity of the proposed method is verified by comparing the experimental data and finite element results of butt welds without misalignment. Meanwhile, the numerical results are in good agreement with the design curves specified by IIW and DNV standards.
KW  - FE fatigue method; butt welding; misaligned weld; fatigue life

DO  - 10.32604/sdhm.2026.086372