Analysis of the Possibility to Assess the Occurrence of Hidden Corrosion in Lap Joints Using Active Thermography

The article details the NDT technique of pulse thermography used for objective diagnosis of riveted lap joints construction. The degradation of materials manifesting in corrosion is inherent in the process of aircraft operation. One type of corrosion is galvanic corrosion occurring in the overlap joints (known as hidden corrosion). As a result of the potential difference between the two layers of the aluminum alloy skin, there occurs the phenomenon of oxidation of the material, producing corrosion products in the form of oxide compounds characterized by heat properties different than those of the base material. Active thermography techniques allow observing infrared energy, which changes due to the difference of thermal properties of the tested materials.