Fatigue Behavior and Mechanism Study on Lugs of TC18 Titanium Alloy

Aerospace structural components are in a complex stress state when they undertake load due to their specific geometric construction. Their fatigue behavior is quite different from the materials that undertake the standard stress state. The research on fatigue behavior of aircraft structures was the foundation of their design and life prediction. Lugs are one of the important connected components of aircrafts. In this paper, the mathematical mechanics’ method was used to calculate the structural feature parameters of TC18 Titanium alloy lugs under several specific loads. The design reference values of structural feature parameters were put forward for lugs. The fatigue behavior and fatigue failure characteristics under specific loads were studied experimentally. The fatigue experiment was conducted to verify the criterion, and the validity of the criterion mentioned above was confirmed by the test results. The fatigue life S-N curves under different loading forms and different mean stresses were researched. The fatigue failure characteristics, such as fatigue crack initiation, propagation, and final fracture, were also studied. These studies provided theoretical support for the anti-fatigue damage design of lugs.