Fatigue Crack Detection in a Multi-Riveted Strap Joint Aluminium Panel

The scope of this paper is the investigation of reliable damage indicators obtained from Lamb wave responses on a multi-riveted strap joint aluminium panel representing a standard joint in aviation. Damage indices based on amplitude and cross-correlation are assessed by examining two data sets. The first set was taken 8 years ago, while the second set was obtained recently. The resumption of the experiment on the aircraft riveted panel after 8 years required a new clamping, a different data acquisition system and involved a new operator amongst other changes. Those variations inevitably caused deviations in the gathered data. The deviations obtained will be examined in the context of the derived damage indices. The application of a second baseline is carried out and its necessity discussed. Additional temperature measurements were recorded for the second phase of the experiment which showed high correlation with the variation of the waveforms and hence with the damage indices. This study gives a good indication of the sensitivity and reliability of a SHM system based on guided waves in complex joint structures. It also provides information about the robustness of the chosen method, as in real-world applications it is more likely that operators will change too.