Effect of structural details on the fatigue failure of welded hollow spherical joints under uniaxial tension.

In order to understand the fatigue failure mechanism of welded hollow spherical joints, a formula of the stress concentration coefficient K_t about α=d/D and β=t/T was deduced based on ANSYS finite element software. The results show that the stress concentration coefficient increases with the diameter D of the hollow sphere and the thickness t of the wall of the steel tube. It also decreases with the diameter d of the steel tube and the wall thickness T of the hollow sphere. The stress concentration coefficient decreases with the increase of a and increases with the increase of β. Fatigue cracks arise from the stress concentration at the fusion zone of the weld, which is the starting point of fatigue failure. Stress concentration is the main reason for the low fatigue strength of welded hollow ball joints. [ABSTRACT FROM AUTHOR]