Fatigue crack growth modeling of attachment lugs

In the present paper, computational procedures for the strength analysis of two cracked lug configurations are proposed. The authors consider the lug with single through-the-thickness crack as well as with single quarter-elliptical corner crack. The stress analysis and the fatigue life evaluations are tackled for both configurations. Numerical approaches based on quarter-point (Q-P) singular finite elements are developed for stress intensity factor calculations. Furthermore, the finite element analysis is applied in order to evaluate the polynomial expression for the stress intensity factor calculation of the lug with one through-the-thickness crack. The residual life estimation of cracked lugs is analyzed by employing the crack growth law based on a two-parameter driving force model. Moreover, the crack growth path for the lug with quarter-elliptical crack is simulated. The reliability of the proposed procedures is verified using experimental fatigue crack growth data. Fatigue life calculations and crack path simulations show a very good agreement with experimental observations.