The fundamental goal of this project is to reduce the cost and unnecessary worker exposure to hazardous materials arising from the paint removal process during programmed depot maintenance for aircraft. The intent is to quantify how environmental factors and external stress fields influence coating system degradation. These factors will be evaluated using laboratory experimentation and analysis, finite element analysis, and outdoor exposure testing. A model that contains the relevant physical and chemical processes that govern the evolution of coating damage upon cumulative exposure will be devised to permit predictions of coating system lifetime.

The overall approach for this work focuses on developing an improved mechanistic understanding of the roles that environmental exposure and stress play on degrading the corrosion barrier properties of the aircraft topcoat and the entire coating system. Finite element methods (FEM) will be employed to both determine stress fields in coating systems near rivet and threaded fastener connections as well as simulate crack propagation in coatings due to fatigue loading. The final task will focus on the development of a process model that can be used to predict the current state of the coating system, based on its exposure and fatigue history. Model calibration testing will be performed at the Center for Corrosion and Structural Testing (C-CoAST) in Key West, FL.

A predictive algorithm for the state of the coating system would facilitate maintenance planning and scheduling as well as reduce unnecessary paint removal. Time-based scheduling does not account for the cumulative damage of the coating system arising from the unique exposure of each aircraft. A model that incorporates the fundamental effects of each environmental parameter will yield damage predictions based upon the measured environmental data and not on an experiment or a proxy sensor.