Abstract
An effort has been undertaken to develop a methodology that defines a set of reference environmental exposure histories that are statistically representative of the weather variation at a specific geographic location. Three years of NOAA weather station data from three different U.S. Military installations were analyzed and modeled to assess wet cycle start, end times and cycle durations over each season. Wet cycle start and end events were defined by transition through the deliquescence and efflorescence Relative Humidity (RH) levels for NaCl thin film solutions. Statistical distributions of wet cycle durations, temperature and RH values for each season were used to define the median, upper and lower percentile bounds for wet cycle exposure. Correlations between temperature, RH and time-of-day phasing were all accounted for in the model. The resulting model output provides a simplified description of daily and seasonal weather variation that is statistically representative, and that can easily be programmed into an environmental test chamber controller for more realistic environmental exposure testing. Results of such test are essential to properly validate corrosion prediction models, corrosion damage indices and coating degradation models under realistic fleet operational environments.
