The detection of inter laminar corrosion in rivetted thin aluminum skins

The fuselage of an aircraft is made by rivetting thin aluminum skins to the sub structure which is then exposed to the environmental elements. Moisture can penetrate between these aluminum surfaces causing inter laminar corrosion. This research describes an optical procedure to inspect large areas of quasi flat surfaces in order to identify areas of suspected inter laminar corrosion followed by an focussed ultrasonic test in the suspected area to confirm the inter laminar corrosion. After a contour scan of the offending area to determine the resulting contour amplitude an FEA model of the area was used to estimate the stress in the aluminum skin.