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Advanced radiographic methods for visualization of corrosion in aircraft structures

Methods for enhanced detection and characterization of corrosion in aircraft structures are presented. A unique Reverse Geometry X-ray system was utilized for real time radiographic imaging of structures. This system has several possible advantages as compared to conventional radiography. First, the x-ray detector can be miniaturized and easily positioned inside a complex structure enabling images of each surface of the structure to be obtained separately. Second, multiple detectors enable the simultaneous acquisition of data from several different perspectives without moving the structure or the measurement system. This provides a means for locating the positions of flaws and enhances separation of features at the surface from features inside the structure. A method is presented for calibration of the eight detectors for reduction of radiographic data to thickness measurement. Results are presented for measurements on a varying thickness sample. Laminographic reconstruction of data from the multiple detector system is presented. Laminographic imaging methods are shown to be capable of separating surface features from corrosion in the lap joint and locating corrosion in multilayer structures. Removal of surface features to enhance definition of corrosion boundaries is discussed.