Fatigue life predictions for riveted lap joints

Abstract

A semi-empirical fatigue life prediction model for riveted lap joints representative of the aircraft fuselage skin connections is developed. The effect of the interference fit between the rivet and the hole is taken into account utilizing fatigue test results for 2024-T3 Alclad aluminium alloy coupons with an open and filled hole. The effect of contact surface friction is considered based on comparisons between the fatigue lives of lap joints from 2024-T3 Alclad sheets and universal rivets with the Alclad contact surface and the fatigue lives of similar joints with the Teflon interfoil which eliminates friction between the sheets. Dependencies between coefficients incorporated into the model to account for the above mentioned effects and several quantities related to the amount of rivet squeezing, and thus representative of the riveting process, are provided. The fatigue life is assumed to be controlled by the local stress amplitude at the critical location of a joint. Analyses of the fatigue test results for the 2024-T3 riveted joints prove that the local stress estimated using the superposition approach can adequately represent the combined effect of the applied loading, interference between the rivet and the hole and faying surface friction condition on the fatigue life. The adequacy of the proposed model is substantiated by a good agreement between the fatigue lives predicted and observed for lap joints from D16 aluminium alloy sheets and round head rivets.