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A novel piezoelectric fibre patch transducer for shear horizontal wave modes

: Köhler, Bernd; Gaul, Tobias; Schubert, Frank; Lieske, Uwe

Fulltext urn:nbn:de:0011-n-5038831 (475 KByte PDF)
MD5 Fingerprint: ec7845b1fa9cff95cb5326eb86004164
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Created on: 4.8.2018

Purschke, M. ; International Committee for Non-Destructive Testing -ICNDT-; Deutsche Gesellschaft für Zerstörungsfreie Prüfung e.V. -DGZfP-, Berlin:
19th World Conference on Non-Destructive Testing, WCNDT 2016 : Munich, Gemany, 13-17 June 2016; Proceedings; USB-Stick
Berlin: DGZfP, 2016 (DGZfP-Berichtsbände 158)
ISBN: 978-3-940283-78-8
Paper 20, 8 pp.
World Conference on Non-Destructive Testing (WCNDT) <19, 2016, Munich>
Conference Paper, Electronic Publication
Fraunhofer IKTS ()

Elastic waves in solids interact with scatterers and structure features, thus giving information about appearance of defects and structural changes. This is widely used in Non-destructive Testing of Materials and in Structural Health Monitoring. Relevant wave modes in isotropic bulk materials are longitudinal and shear waves which can be vertically or horizontally (with respect to the coupling surface) polarized. Guided elastic waves in plate like and pipe like structures are a superposition of several of - in general dispersive – wave modes of the Lamb wave and Shear Horizontal wave type. Horizontal polarized shear waves as the SH0 plate wave and the SH wave in isotropic solids have several advantages: they are dispersion free and don’t experience mode conversion while reflected at a backwall. For generation of SH waves, electromagnetic acoustic transducers (EMAT) are commonly used as well as piezoelectric and magnetostrictive based transducers. All these types are rather bulky and heavy, either due to the need of a backing material or to strong magnets. The paper presents a novel, lightweight and thin alternative transducer for shear horizontal elastic waves. Due to its characteristics it is most appropriate for applications where low mass and small sensor dimensions are desired. The principle of the shear horizontal (SH) wave transducer based on piezoelectric fibre patches (PFP) is described. Numerical simulation results are given for the elastic wave field in a plate generated by such an SHPFP-transducer. These results demonstrate the dominance of the SH0 mode. 3D-Laser vibrometry measurements of the wave field are in good agreement with the simulation. We discuss possible further developments of the SHPFP transducer to allow 1D directivity and we also discuss various possible sensor applications.