Linking Riveting Process Parameters to the Fatigue Performance of Riveted Aircraft Structures

Abstract

The onset of widespread fatigue damage in riveted aircraft structure has been linked to sharp gradients of stress arising from contact between rivets and rivet holes. In addition, the mechanics of load transfer in lap joint structure (and resulting damage) is influenced by the through-thickness restraint offered by the installed rivet. Finally, the propagation of fatigue cracks at and around the rivet/hole interface is tied to the residual stress field induced during the riveting process. In light of the influence that rivet installation has on the fatigue performance of riveted joints, the aim was to link details of a quasi-static, squeeze force-controlled riveting process as provided by finite element modeling to the resulting residual stress field in a single-lap joint structure. Supporting experiments provide insight into the inelastic response of the rivet material and validation of the model results. These results from the model reveal both a strong through-thickness gradient in residual stresses and a change in the distribution of residual hoop stress near the rivet/hole interface with squeeze force. Comments are also made regarding the relationship between riveting process parameters and trends in observed fatigue failures of riveted lap joint test articles.