Diaphragm resonance-based fiber optic hydrophone

Saxena, Indu; Guzman, Narciso; Hui, Kaleonui J.; Pflanze, Stephen

doi:10.1117/12.852898

Cited by 5 publications

(1 citation statement)

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“…The next stage builds on the measured PZT responses by substituting the PZT receivers with a fixed array of fiber optic transducers, and instead of moving the receiver along the surface to different points, several fiber transducer locations in a single strand of fiber, when in contact with the test surface, acquire position-sensitive responses covering the entire area to be investigated. Fiber optical Bragg grating transducers [16][17][18][19][20][21][22] are well-known spectrally selective optical elements intrinsic to optical fiber, (spectral plot of 19 shown in Figure 4) that are extremely sensitive to physical changes such as temperature and strain. However, this extreme strain sensitivity is also challenging when dynamic ultrasound displacements four orders of magnitude smaller than large static effects are to be measured.…”

Section: Fiber Bragg Grating Ultrasound Transducers or Bruts In Pliabmentioning

confidence: 99%

Disbond detection in a composite honeycomb structure of an aircraft vertical stabilizer by fiber Bragg gratings detecting guided ultrasound waves

Saxena¹,

Guzman

Hui

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part C:

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Efficient and accurate nondestructive inspection systems that save time can benefit scheduled maintenance of aircraft structures. Portable nondestructive inspection techniques capable of scanning larger area structures could find great utility and save considerable time and labor. Contemporary fixed location nondestructive inspection systems, such as the gold standard water-coupled ultrasound imaging by the “squirter” require structural disassembly of the part to be inspected and transportation to/from dedicated location. For large aircraft structures, such as vertical or horizontal stabilizers, this adds weeks to the off-site nondestructive inspection process. An on-site ultrasound detecting method for larger areas, comprising a flexible transducer panel of embedded fiber optic Bragg gratings that is lightweight and portable, and reusable over different structures, is described here. It is shown that this fiber Bragg grating embedded ultrasound transducer panel and readout hardware–software system can map tiny surface displacements of guided wave ultrasound, onsite, over an area of approximately 2 square feet in just over 10 min. The test sample is a sandwich structure with composite skins on both sides of an aluminum metal honeycomb section of an aircraft vertical stabilizer with an artificial engineered disbond. The ultrasound propagation data acquired at 612 positions over the large area, enables in situ nondestructive inspection of defects/ damage by comparing post-damage data with baseline data, and is independent of the material information.

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