<title>NDT on wide-scale aircraft structures with digital speckle shearography</title>

Abstract

Carbon fiber technology and other lightweight constructions are used more and more for airplane parts. Modern airliners are already equipped with such components as e.g. in the vertical and horizontal stabilizer, rudder, airbrakes and spoiler. The application of the new materials is accompanied by new requirements for an optimal dimensioning. In this case, the investigation with respect to material and construction imperfections is of high interest. In order to receive a high safety of operation possible damages must be recognized prematurely within control examinations to prevent the total breakdown of the device. For this reason, adapted examination designs and especially developed testing methods are necessary. An appropriate testing method must meet the following requirements: (1) nondestructive evaluation, (2) inspection of large aircraft structures, (3) working with non- cooperative surfaces, (4) non-ambiguous flaw interpretation, (5) flexible and simple in operation. A testing method which can manage such examination designs is the shearography. It is a robust interferometric technique to determine locations with maximum stress on various material structures under an appropriate load. The procedure is also suitable for inspection where only one side of the aircraft-structure to be tested is accessible. This paper describes a complete procedure including loading and image processing facilities for structural testing and flaw recognition on non-cooperative aircraft surfaces.