Predicting Cumulative Galvanic Corrosion Damage in Aircraft Structures using Environmental Exposure Measurements

Environmental exposure history, measured using corrosion sensors, is used to drive a computational model and predict the cumulative galvanic corrosion damage. Knowing th eenvironmental exposure of an aircraft over the course of its lifetime is critical to making meaningful predictions of accumulated corrosion damage. Dynamic environmental monitoring using sensor technology provides a significant advantage compared to using historical atmospheric data records. Estimates of time-of-wetness (TOW) are made through statistical manipulation of the sensor data so that discrete environmental characterizations (WET, SEMI- WET and DRY) of the total exposure history can be derived. Computational models require information on electrolyte conductivity, film thickness, and polarization properties to make predictions of galvanic stress and metal loss. By combining TOW data with electrolyte properties representing each of the discrete environmental exposure conditions, and using corrosion rates from computational models, the cumulative corrosion damage for a defined operational period can be predicted. A demonstration of this new methodology (corrosion Service Life Model) is presented using actual environmental exposure data collected onboard a naval vessel. The effects of crevice and pitting corrosion can also be included in this predictive model. The approach is applicable not only to aircraft but to a wide range of structures subject to atmospheric corrosion.