Modeling Approach for Galvanic Corrosion Protection of Multi-material Aircraft Structures

The paper gives an overview of the development and experimental validation of a computational model for simulating galvanic corrosion in specific application case scenarios appearing in an aircraft environment. The numerical approach is based on solving the electro-neutrality equation with a three dimensional Boundary/Finite 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 electric current density and potential distribution on the surface.

The focus of the study is thin electrolyte conditions that could occur in the upper part of A/C structures. A model considering a co-planar unpainted bi-material combination composed exemplarily of Aluminium AA2024 and carbon fibre reinforced polymer (CFRP) has been developed. An experimental set-up has been established for validation of the computational results. The validation approach is explained and the results obtained are presented. Good agreement has been obtained between observed and simulated data. This conceptual model can be applied to different multi-material combinations relevant for aircraft structures. In particular variations in the environmental condition are considered, including for example different thicknesses of electrolyte film, and different aggressiveness of electrolytes. Further parameter studies are discussed to show the effect of different physical properties of the electrolyte on corrosion rates and total current changes in the materials involved.

Keywords: Galvanic corrosion, AA2024, CFRP, Boundary/Finite Element Method, Aircraft

Acknowledgement: This work is supported by the Six Framework Programme for Research and Development of the European Commission in the Specific Targeted Project “SICOM”, Priority 4, Aeronautic and Space ; Project No.: AST5-CT-2006-030804 SICOM.