Macroscale Modeling Solutions for Integrity Assessment of Corrosion-Related Damage

Abstract Military aircraft operating in challenging environments frequently develop corrosion damage. Nearly 80% of inspected corrosion damage sites in aircraft were found to have fatigue cracks; frequently these cracks initiated from corrosion pits. These findings reveal the importance of developing advanced predictive tools to investigate the effects of corrosion and mechanical stress on aircraft operational performance. A new computational approach to characterize the effects of corrosion related defects on fatigue life is presented. This approach includes determination of SIF solutions for corrosion pit cavities with different periphery crack shapes and locations, evaluation of pit proximity interaction behavior, and simulation of pit-induced cracking to capture crack propagation path and predict impact on fatigue life. A brief background discussion on phenomenological models (Murakami defect area, Kondo pit-to-crack competition model) commonly used to evaluate corrosion related defects is also provided for comparison. This work provides a new paradigm in predictive modeling where mechanistic models are developed to better quantify the cracking susceptibility of corroded surfaces. Our approach is driven by a dual mandate to develop science-based predictive methods to assess corrosion damage and support life cycle management, but with a focus on engineering scale implementation.