Improving Fatigue Performance of AA 2024-T3 Clad Aeronautical Riveted Lap-Joints Using Laser-Peening

摘要

This study analyses the application of different strategies of Laser-Peening (LP) on Riveted Lap Joint (RLJ) samples to improve the fatigue performance of this crucial component of aircraft architecture. RLJ have been laser-peened and consequent Residual Stresses (RS) through the thickness were measured using Incremental Centre Hole Drilling (ICHD) method. Different LP strategies produced significant different RS fields not only by varying LP process parameters, but also by the definition of designated LP area on the component and by the sequence single laser-spots are arrayed to cover the designated LP area. Fatigue tests of baseline (un-peened) and LP samples revealed that significant fatigue life improvements up to a factor of 3.54 can be achieved if the LP strategy manages compressive and associated tensile RS in the component. Furthermore, post-mortem fractography showed that the crack initiation mechanism of LP RLJ samples can be altered beneficially and detrimentally depending on the LP strategy and its consequent RS field. It was found that treating fatigue critical locations locally by LP is more beneficial to fatigue life improvement than global introduction.