Modelling the effects of intergranular corrosion around a fastener hole in 7075-T651 aluminium alloy

Intergranular corrosion (IGC) is potentially a major concern for the structural integrity of aerospace aluminium alloys; the crack paths and networks formed make it particularly difficult to predict its impact on structural integrity, even when the likely location of the corrosion is known. IGC is a particular problem for the Royal Australian Air Force AP-3C Orion aircraft, where it is causing a significant increase to maintenance loads due to the unknown impact on structural integrity. s paper a brick wall-style computational analysis is combined with a python script to create a finite element (FE) model of a plate-with-hole containing a random IGC path. The brick wall style analysis was chosen over measuring actual corrosion paths as analysing a large number of paths takes significant amounts of material, which is at a premium as it needs to be taken from the aircraft. The FE model produced realistic stress concentrations at the bore of the hole and showed that an IGC path that deviates vertically along its length will produce a small but noticeable change in the local stress concentration.