Characterization of Hidden Airframe Corrosion by Time-Resolved Infrared Radiometry (TRIR)

Since hidden corrosion is expected to be the primary factor limiting the service life of military and civilian aircraft, the problem of detection of hidden corrosion needs to be solved to allow for life extension. A quantitative thermographic NDE technique for the characterization of hidden corrosion is under development along with supporting theoretical analysis. In earlier work [1,2] we have shown that the technique of time-resolved infrared radiometry (TRIR) is an effective method for quantitatively detecting coating thickness variations and for characterizing the degree of coating disbonding in terms of equivalent air gaps. In this paper we examine the applicability of TRIR techniques to the characterization of corrosion damage in airframes by investigating plate specimens of 2024-T3 aluminum with both milled defects and corroded regions produced by an accelerated corrosion test.