Improved SH0 Guided Wave Transducers Based on Piezoelectric Fiber Patches

Kim, Yongtak; Gaul, Tobias; Köhler, Bernd

doi:10.3390/s19132990

Cited by 10 publications

(7 citation statements)

References 34 publications

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“…This second transducer could be a thin piezoelectric wafer glued to a plate, which is commonly used in SHM with guided elastic waves. Other examples include lightweight fiber-based SHM transducers [ 14 , 15 , 16 ], SHM transducers introducing shear tractions on the surface [ 17 , 18 , 19 , 20 ], and electromagnetic acoustic transducers [ 21 , 22 ], to name just a few. Laser excitation of ultrasound can also be studied in both thermoelastic and ablation regimes.…”

Section: Discussionmentioning

confidence: 99%

Electromechanical Reciprocity Applied to the Sensing Properties of Guided Elastic Wave Transducers

Köhler

Schubert

Barth

et al. 2022

Sensors

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Guided elastic wave (GEW) transducers for structural health monitoring (SHM) can act as transmitters (senders) and receivers (sensors). Their performance in both cases depends on the structure to which they are coupled. Therefore, they must be characterized as system transducer- structure. The characterization of the transducer-structure as transmitter using a Scanning Laser Doppler Vibrometer (SLDV) is straightforward, whereas its characterization as receiver is non-trivial. We propose to exploit electromechanical reciprocity, which is an identity between the transfer functions of electrical-to-mechanical and mechanical-to-electrical conversions. For this purpose, the well-known electromechanical reciprocity theorem was adapted to the following situation: The two reciprocal states are “electrical excitation and detection of the surface velocity at point P” and “mechanical excitation at P and measurement of the electrical quantities”. According to the derived formulas, the quantities on the mechanical and electrical sides must be chosen appropriately to ensure reciprocity as well as that the corresponding transfer functions are equal. We demonstrate the reciprocity with experimental data for correctly chosen transfer functions and show the deviation in reciprocity for a different choice. Furthermore, we propose further applications of electromechanical reciprocity.

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Section: Discussionmentioning

confidence: 99%

Electromechanical Reciprocity Applied to the Sensing Properties of Guided Elastic Wave Transducers

Köhler

Schubert

Barth

et al. 2022

Sensors

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“…7 shows an example where a full wavelength λ is inscribed instead of only half of the wavelength. Our new design includes the double SHPFP of [22] with all the advantages reported in that previous publication.…”

Section: Concept Of a Mode-switchable Pfpmentioning

confidence: 98%

“…In practice they are elastically coupled due to the finite mass and stiffness ratios. Consequently, a multiphysics problem arise, which in most cases can only be solved by numerical simulations [22]. However, situations exist in which the systems are decoupled.…”

Section: General Remarksmentioning

confidence: 99%

“…The horizontal and vertical axis in the lower row images are from 0 to 152 mm and from 0 to 100 µs, respectively. These experimental B-scans are reproduced from [23] with permission from the American Institute of Physics (Color figure online) investigated [22]. It was shown that the directivity and purity of the SH wave generation could be improved by operating two SHPFP stacks instead of one.…”

Section: Shear Wave Transducermentioning

confidence: 99%

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A Mode-Switchable Guided Elastic Wave Transducer

et al. 2020

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Increasing the safety demands of various progressively complex structures (e.g., in aerospace, automotive engineering, and wind power technology) and the parallel goal of reducing inspection costs set new objectives in the field of ultrasonics and guided elastic wave measurements. The focus is to deliver applicable sensors attached permanently to a particular structure for on-demand inspections. Piezoelectric fiber patches (PFPs) are known as lightweight and structure-conforming transducers for guided elastic wave generation and detection. We propose a new PFP concept combining advantages of different previous designs. With the new approach, a user can switch between a Lamb wave and a shear horizontal wave excitation by partially changing the polarity of the transducer electrodes. After summarizing the existing PFP variants, the new concept is introduced and experimentally verified by a three-dimensional laser Doppler vibrometer visualization of excited waves. Moreover, the first prototype of the new PFP transducer is presented.

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“…Ultrasonic transducers for the generation and reception of guided waves in plates can be classified as either contact or noncontact. Contact transducers include piezoelectric angle beam transducers [ 1 ], piezoelectric wafer arrays [ 9 ], and piezoelectric fiber transducers [ 10 , 11 ]. For example, reference [ 11 ] developed a piezoelectric array that can simultaneously generate Lamb and SH waves using polyvinylidene difluoride (PVDF) film.…”

Section: Introductionmentioning

confidence: 99%

Modeling Magnetostrictive Transducers for Structural Health Monitoring: Ultrasonic Guided Wave Generation and Reception

Guo

Lissenden

2021

Sensors

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Ultrasonic guided waves provide unique capabilities for the structural health monitoring of plate-like structures. They can detect and locate various types of material degradation through the interaction of shear-horizontal (SH) waves and Lamb waves with the material. Magnetostrictive transducers (MSTs) can be used to generate and receive both SH and Lamb waves and yet their characteristics have not been thoroughly studied, certainly not on par with piezoelectric transducers. A series of multiphysics simulations of the MST/plate system is conducted to investigate the characteristics of MSTs that affect guided wave generation and reception. The results are presented in the vein of showing the flexibility that MSTs provide for guided waves in a diverse range of applications. In addition to studying characteristics of the MST components (i.e., the magnetostrictive layer, meander electric coil, and biased magnetic field), single-sided and double-sided MSTs are compared for preferential wave mode generation. The wave mode control principle is based on the activation line for phase velocity dispersion curves, whose slope is the wavelength, which is dictated by the meander coil spacing. A double-sided MST with in-phase signals preferentially excites symmetric SH and Lamb modes, while a double-sided MST with out-of-phase signals preferentially excites antisymmetric SH and Lamb modes. All attempted single-mode actuations with double-sided MSTs were successful, with the SH3 mode actuated at 922 kHz in a 6-mm-thick plate being the highest frequency. Additionally, the results show that increasing the number of turns in the meander coil enhances the sensitivity of the MST as a receiver and substantially reduces the frequency bandwidth.

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Improved SH0 Guided Wave Transducers Based on Piezoelectric Fiber Patches

Cited by 10 publications

References 34 publications

Electromechanical Reciprocity Applied to the Sensing Properties of Guided Elastic Wave Transducers

Electromechanical Reciprocity Applied to the Sensing Properties of Guided Elastic Wave Transducers

A Mode-Switchable Guided Elastic Wave Transducer

Modeling Magnetostrictive Transducers for Structural Health Monitoring: Ultrasonic Guided Wave Generation and Reception

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