ABSTRACT
A comprehensive modeling exercise was undertaken to better understand, the spatial distribution of corrosion damage, measured on aircraft representative, galvanic test articles, exposed to two significantly different corrosive environments. One set of test articles was exposed to ambient conditions in a coastal marine environment for approximately two months, while a second set was further exposed to controlled seawater spray dosing for an additional two months. Both environmental loading scenarios are assessed, analyzed, and modeled. The performance of a three-dimensional (3D) finite element model, of the multi-material galvanic test article, is discussed, along with some of the challenges associated with selecting appropriate input parameters to best represent the two different exposure conditions. The measured spatial distribution of corrosion damage is compared to the galvanic simulation model solutions. A complex pattern of corrosion damage is observed, that includes, localized galvanic corrosion at the fastener, crevice corrosion beneath the bushing flange, and galvanic interaction between the fastener and larger diameter bushing. The sensitivity of the models to electrolyte resistance (film thickness, conductivity) and extent; and the metal resistance (polarization curves), representing each environment, are explored.
