Corrosion is a major concern to the aerospace community when evaluating the structural integrity and service-life potential of an airframe. The estimation of corrosion and characterization of material parameters due to such corrosion is of the paramount interest. In this study, corrosion characterization and estimation is considered by using vibration spectrum that can be obtained from non-destructive testing. To that end, aluminum 7075-T6 extrusions were exposed to the exfoliation corrosion environment specified in ASTM G 34 for various times, and the resultant mass loss was measured for each exposure. The corrosion attack was confined to a narrow band centered on the length of a beam specimen by masking the extrusion. Theoretical modeling and lab scale dynamic testing were conducted to establish the correlation between the mass loss and the associated spectral characteristics of the beam (natural frequencies). This research program demonstrates that changes in mass due to exfoliation corrosion may be identified by the measurable change in the spectrum. Estimation/characterization techniques based upon a low dimensional mathematical model as well as based only upon experimental data (natural frequencies) are developed. Successful non-destructive dynamic characterization of aluminum extrusions, therefore, can be the basis of corrosion evaluation and health monitoring of structures operating in corrosive environments.

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