Effect of coupling damage on fatigue behavior of 2198‐T8 aluminum‐lithium alloy thin sheet for fuselage

Abstract Based on fatigue experiment and digital image correlation (DIC) technique, the fatigue damage behavior and the failure mechanism of the 2198 aluminum‐lithium alloy thin sheet used for the fuselage were investigated. Firstly, the influence of hemispherical insert size, impact energy, and rivet hole size Φ on the fatigue performance was explored. Secondly, the axial strain distribution and crack propagation behavior of the coupling damaged specimen under the fatigue cyclic loading were characterized by DIC. The results are as follows: the axial strain along the dent path and the rivet hole section path indicates that there exists a competitive relationship between the discontinuity caused by the rivet hole and the dent damage under the fatigue load. For specimens impacted by the same insert, the critical local plastic strain rate for the transition point of the fatigue fracture is related to the rivet hole size Φ , and it increases with the rise of Φ . After the dent damage being quantified, the final fracture position could be determined by the numerical comparison method.