Research on ⅡW multiaxial fatigue criterion based on notch stress approach

Multiaxial fatigue strength evaluation of welded joints is a complex subject for engineering. Based on ⅡW multiaxial criterion, experimental data from published literatures were re-evaluated using notch stress approach. The results reveal that the uniaxial fatigue assessment S-N curve recommended by ⅡW is unfit for multiaxial fatigue. Whereas, the data points of proportional loading and non-proportional loading have good coincidence under notched stress system. The assessment result is dangerous when the number of cycles is in the range of 1×10⁴ ~1×10⁵, and it is too conservative over 1×10⁵ times. Based on this, the S-N curve (FAT=430 MPa, m=5.8) with the probability of survival P_s=97.7% is proposed for both proportional and non-proportional loading. This work can provide useful references for fatigue life prediction of engineering welded structures.