A Holographic Interferometric Technique for the Detection and Computerized Recognition of Structural Faults in Semi-Monocoque Structures

Abstract

A technique and associated hardware has been developed to apply pulsed holographic interferometry as a non-destructive inspection (NDI) tool for the location and identification of structural faults in aluminium aircraft fuselages such us those used in the present air transport fleet. This system has shown its ability to identify faults such as cracked stringers and frames, loose rivets and other defects which occur in service, many of which are second and third layer faults.

The holographic camera system has been ruggedly designed so it is suitable for field operations in industrial locations. Several novel techniques are involved, including the method of excitation to obtain an optimum condition where the structural fault is likely to be made apparent, and the design features of the holographic camera, which is integral to the compact laser head. Importantly, the system records both the relative and actual phase of the vibrationally induced antinodal structure of the fuselage undergoing excitation and NDI.