AA&S Paper

Combining Galvanic and Mechanical Stress Solutions Using a Risk Mapping Approach to Improve Corrosion Related Damage Assessment

Thomas Curtin, Robert Adey, Sharon Mellings

Tear-down inspections of aircraft indicate that most structural failures initiate at corrosion features - nearly 80% of corrosion damage sites identified to have initiated cracks. Therefore a systematic approach is needed for galvanic management of airframes.

In this paper a computational approach is developed to identify locations where corrosion damage is most severe, introduce corrosion damage representative flaws into structural models at these locations, and determine the related stress intensity factors. This approach is demonstrated using a bolted aerospace fastener where the spatial distribution of corrosion damage is determined from a galvanic analysis.

By combing both the galvanic and structural solutions it is possible to assess the impact of structural load on the local stress gradients present at corrosion damage sites; thereby better informing service life predictions. A risk map is created using a notional scheme to indicate areas where cracks are likely to grow given the combined environmental and mechanical loading. This methodology has the promise of improving corrosion related structural assessment and could be extended to determine critical cracks sizes and fatigue crack growth rates for corrosion impacted structures.

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