GALVANIC CORROSION MECHANISMS ANALYSIS AND MODELING FOR F-35 GRAPHITE/BMI COMPOSITE-METALLIC AIRFRAME JOINTS

The P2SI team objective in this proposed research effort is to develop an inherently corrosion resistant composite/metallic joint design. As coatings and sealants deteriorate in service the joint will be inherently corrosion resistant. This will be achieved through a thorough understanding of how the fundamentals of galvanic corrosion relate to corrosion susceptibility of the F-35's composite-metal joints. In this effort, we will experimentally validate our approach using parameters from the F-35 baseline design. The P2SI approach will identify composite-metallic joint configuration dependent and independent variables that directly affect the potential for galvanic corrosion. We will investigate the corrosion rate and effect of corrosion on joint integrity and strength. This will enable us to establish allowable tolerances for design and manufacturing that will protect joints from catastrophic galvanic corrosion failure, even in the event of coating and sealant deterioration in service. In Phase I, multi-variable regression analysis will be performed on the data to model observed effects. We will perform environmental exposure, detailed corrosion and corrosion rate analysis, and residual mechanical property measurements on F-35 joint-based specimens. This approach will ensure maximum relevance of the data and modeling performed under this effort towards state-of-the-art airframe structural design and analysis.