Acoustic Emission Based Corrosion Imaging as a Possible Method for Identification of Localized Atmospheric Corrosion of Aluminum Structures

Atmospheric corrosion of aluminum alloys is a significant damage case that can occur in many industrial sectors, such as aircraft. To ensure the structural integrity of the affected mechanical structures, structural health monitoring (SHM) is considered a powerful tool. The acoustic emission (AE) method is therefore promising, as it is well suited to localize damage such as corrosion and has already shown to be able to estimate the extent of corrosion. However, the localization and quantification of low-amplitude AE events, such as those caused by atmospheric corrosion of aluminum alloy structures, have not been addressed. The present experimental study investigates the potential of the AE method to localize, quantify, and also characterize the type of atmospheric corrosion of thin-walled aluminum structures by so-called AE-based corrosion imaging, i.e., investigates the potential of AE for full corrosion identification. This AE-based corrosion imaging combines precise AE source localization results from a large number of individual AE events during corrosion to create images for the evaluation of the occurring corrosion. Such AE-based corrosion images can not only be used to localize corrosion, but it is shown that they can assist in estimating the spatial extent of it and also have the potential to characterize corrosion types by considering the temporal evolution of the corrosion images. Through the conducted study, the high potential of the AE method to enable full corrosion identification for future SHM applications for corrosion of aluminum structures is demonstrated.