Validation of a Galvanic Corrosion Model for AA2024 and CFRP with Localised Coating Damage

摘要

The paper presents the development and experimental validation of a computational model for simulating galvanic corrosion in typical case scenarios appearing in an aircraft environment. The numerical approach is based on the three dimensional Boundary Element Method. Amongst the inputs of the problem are: geometrical description and physical properties of the electrolyte, as well as macroscopic polarisation curves of the active electrodes. The main outcomes of the model are corrosion rates, electric current density and potential distribution. The case study used for the validation consists of a co-planar pair of Aluminium AA2024 and carbon fibre reinforced polymer (CFRP) immersed in saline solution with variable coating conditions. In particular, the situation of a circular damage ("pinhole defect") of a coating of very high insulating properties on the anodic side of the sample is considered. A comparison between experimental measurements, including potential and total current flowing between anode and cathode, and the corresponding simulation results is presented for different variations of the modelling scenario. Very good agreement has been obtained between observed and simulated results for systematic variations of the case study which consider different locations of the damage in the sample, different surface area ratios between anodic and cathodic regions, and different electrolyte conductivities. The successful validation of the modelling approach has enabled its use for simulating galvanic corrosion in more complex structural components of an aircraft as illustrated in this paper.