Detection and Characterization of Cracks and Corrosion in Aging Aircraft Structures (Part II)

摘要

In this section we present some recent results of an experimental study of the factors determining microcrack development and the microcrack development processes in flush-riveted aluminum alloy joints. These results are taken from the work of Connor et al. The development of the microcracks and how they formed major propagating cracks were followed using both optical and acoustic microscopes. While the optical microscope gives information about the specimen surface, the scanning acoustic microscope gives an image through the thickness projected onto a plane. The hidden surface of the specimen is included in the projection. Thus cracks are revealed that are not on the outer surface of the flush head riveted panel. Since cracks initiate below the outer surface of the specimen, the scanning acoustic microscope is essential to this investigation.