PROBABILITY APPROACH FOR PREDICTION OF CORROSION AND CORROSION-FATIGUE LIFE

A probability approach for life prediction is developed and illustrate d through a simplified model for the pitting corrosion and corrosion f atigue crack growth in aluminum alloys in aqueous environments. A meth od for estimation of the cumulative distribution function (CDF) for th e lifetime is demonstrated by using an assumed CDF for each key random variable (RV). The basic aim of this approach is to make predictions for the lifetime, reliability, and durability beyond the range of typi cal data by integrating the CDFs of the individual RVs into a mechanis tically based model. The contribution of each key RV is considered, an d its significance is assessed. Thus, the usefulness of probability-ba sed modeling is demonstrated. It is noted that physically realistic pa rameters were assumed for the illustrations. As such, the results from analysis of the model qualitatively agree quite well with experimenta l observations. However, these results should not be construed to repr esent behavior in actual systems. Because of these assumptions, confid ence levels for the predictions are not addressed.