Ultrasound imaging of a 2D periodic heterogeneous medium

Speaker:
Hafidi Alaoui, Hamza; INSTITUT DE MÉCANIQUE ET D'INGÉNIERIE; France

Authors:
Deschamps, M.; CNRS; France
Ducasse, E.; Arts et Metiers ParisTech; France
Hafidi, H.A.; Université de Bordeaux; France
Rodriquez, S.; Université de Bordeaux; France

ID: ECNDT-0237-2018
Session: PAUT-Signal processing
Room: G2
Date: 2018-06-13
Time: 15:20 - 15:40

Detecting, localizing and identifying defects in homogeneous media using ultrasound has been an active research topic for decades. The present work focuses on the experimental detection and localization of defects in strongly heterogeneous media. The medium under investigation in this work is made of a regular 2D pattern of steel bars immersed in water. It is investigated with a transducer array in pulse echo mode. Such a medium exhibits long lasting time responses due to the multiple acoustic interactions between the numerous bars. For this reason, the signature of a potential defect is hidden in the experimental response. Furthermore, even when this signature is isolated, classical Time Of Flight methods tend to fail because they rely on the assumption the medium is homogeneous. The present work uses the topological imaging method to overcome the heterogeneous nature of the medium. The experimental results obtained are compared to the application of more classical imaging processes. As the method relies on a numerical model of the unperturbed medium, extra effort has been made for simulating the experiments. It is also investigated if the method takes advantage of the complexity of the medium in terms of localization and resolution, as it has been demonstrated in homogeneous reverberating media.