Guided-wave based Non-Destructive Evaluation (NDE) and Structural Health Monitoring (SHM) systems validation under realistic conditions or environment requires complex setups. Numerical or theoretical approaches are useful to save time and cost associated with experimental tests but the interaction with realistic geometrical (rivets, thickness changes, stiffeners, extrusions) or damage features (fatigue cracks, fillet cracks, delaminations, disbonds) must be accurately captured in order to be representative. In this paper, an experimental methodology is presented for estimating the far-field scattering of geometrical or damage features. The principle is based on the use of a Hankel transform of the measured 3D velocity field in order to evaluate with precision the scattered pattern using a spatially averaged method. Application to scattering of a hole with simulated machined and real fatigue cracks is proposed. It is observed that the simulated machined crack generally used as a reference standard can only model accurately the transmission behaviour while the scattering patterns are only similar when the wavelength is about the size of the crack, limiting the practical use of machined cracks for experimental validation of SHM or NDE systems.
Nicolas Quaegebeur, Nidhal Bouslama, Maxime Bilodeau, Patrice Masson, Ahmed Maslouhi, and Philippe Micheau, "Guided wave scattering by a geometrical or damage feature: application to fatigue crack and machined notch," Proc. SPIE 10170, Health Monitoring of Structural and Biological Systems 2017, 101701O (Presented at SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring: March 28, 2017; Published: 5 April 2017); https://doi.org/10.1117/12.2258646.
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