Experimental and numerical investigation on fatigue performance of non-load-carrying fillet welded joints

Fatigue performance of non-load-carrying fillet welded details was investigated by experimental and numerical approaches in this paper. Fatigue tests were conducted on 26 non-load-carrying cruciform fillet welded joints. 23 effective fatigue test data were acquired and experimental S-N curve was established. The test results are representative on reflecting the fatigue performance of the non-load-carrying fillet welded details fabricated in China and provide essential data for developing related design codes. In comparison with the test data, the design S-N curve in Eurocode3 is proved to be suitable in generally but does not have sufficient safety stock for this batch of specimens. Afterwards, 3D mix-mode fatigue crack growth simulation was developed based on four initial crack assumptions. Comparisons between the predicted fatigue lives and experimental fatigue lives were carried out. It is found that the line cold lap assumption with 0.1 mm initial value can give the best prediction on the average experimental fatigue lives. Nevertheless, I-type line crack assumption with 0.01 mm initial value can provide suitable prediction in line with the experimental S-N curves of 95% survival probability and therefore it is recommended to be taken for fatigue crack propagation analysis when no specific inspection information is available. The influence of misalignment on fatigue lives are also analyzed, which could provide useful reference for practical engineering projects.