The implementation of structural health monitoring systems in modern aircraft structures requires a deeper understanding of impact and piezoelectric generated Lamb wave propagation on carbon fibre reinforced plastics. In this paper a digital shearing interferometry method is presented that visualizes Lamb waves excited by impact events or piezoelectric actuators. The contactless full field measurement of these waves is realized by a Mach-Zehnder interferometer which combines spatial phase shifting and shearography. The latter is a laser based technique whereby the first order derivates of the displacement is indicated. Since a dynamical process is observed the spatial phase shifting technique is required. The optical implementation of both techniques within the interferometically setup and experimental results with the possibility to measure the out of plane displacement are presented. Therefore the underlying wavefield is reconstructed from the measured first order derivatives. Subsequently these results are compared with a one point measuring method and FEM simulation.
Inspection of Lamb waves in carbon fiber composites using shearographic interferometry
Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security, 2008 ; 693403/1-693403/12
2008
12 Seiten, 21 Quellen
Aufsatz (Konferenz)
Englisch
Shearographic inspection of aircraft structure
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