Crack extension analysis and fatigue life assessment of single lug and yoke joints containing initial defects

Abstract

To investigate the impact of initial cracks on the fatigue performance of single lug and yoke joints, fatigue testing was performed for defective welding joint models. The crack extension behaviors were investigated based on the theories of fracture mechanics using ANSYS-FRANC3D interactive technology, and the effects of the initial crack location, morphology pattern, and surface angle on fatigue performance were determined. The results showed a fatigue failure mode in which the crack extended along the welding line for single lug and yoke joints. The fatigue life was shorter when the initial crack was in the corner of the single lug plate. Moreover, the crack growth rates during the early stage of crack extension varied significantly with different initial crack morphology patterns. However, the crack growth rates during the later stages were similar to one another. The remaining fatigue life increased with the shape ratio for the same crack depth. Finally, the crack growth rate was the fastest, and the remaining fatigue life was the shortest when the initial crack surface angle was inclined toward the stress concentration area.

Crack propagation analysis and fatigue life assessment of high-strength bolts based on fracture mechanics

“…Therefore, the length of the crack front needs to be normalized. The finite element simulation of the Dhamari study shows that any initial crack shape will rapidly develop into a common profile, after which, the crack will propagate in a similar manner 37 , 38 , as shown in Fig. 9 .…”

Numerical simulation and experimental verification of fatigue crack propagation in high-strength bolts based on fracture mechanics

“…Therefore, the length of the crack leading edge needs to be regularized. The finite-element simulation of the Dhamari 28,40 study shows that any initial crack shape will rapidly develop into a common profile, after which, the crack will propagate in a similar manner, as shown in Figure 8. Usually, an ordinary initial crack can be simplified to a surface crack with a length of 2c and a depth of a.…”

“…Among them, the MTS criterion is more intuitive, which has been verified by many experimental observations, [28][29][30] so it has been widely considered and applied. This method is also used to determine the crack propagation angle in this paper.…”