Preferential directional coupling to ultrasonic sensor using adhesive tape

Self Cite

Guided waves (GW) and acoustic emission (AE) -based structural health monitoring (SHM) have widespread applications in structures, as the monitoring of an entire structure is possible with a limited number of sensors. Optical fiber-based sensors offer several advantages, such as their low weight, small size, ability to be embedded, and immunity to electro-magnetic interference. Therefore, they have long been regarded as an ideal sensing solution for SHM. In this review, the different optical fiber technologies used for ultrasonic sensing are discussed in detail. Special attention has been given to the new developments in the use of FBG sensors for ultrasonic measurements, as they are the most promising and widely used of the sensors. The paper highlights the physics of the wave coupling to the optical fiber and explains the different phenomena such as directional sensitivity and directional coupling of the wave. Applications of the different sensors in real SHM applications have also been discussed. Finally, the review identifies the encouraging trends and future areas where the field is expected to develop.

Section: Remote Bonding Of Fbg Sensorsmentioning

confidence: 99%

Optical Fiber Sensors for Ultrasonic Structural Health Monitoring: A Review

Soman

Wee

Peters

2021

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“…This produces a shift in the Bragg wavelength, which is related to variations in the fiber strain. A relevant application of these optical strain sensors is structural health monitoring based on the collection of ultrasonic waves [ 101 , 102 , 103 , 104 ]. For this purpose, adhesives are typically used for bonding the strain measuring fiber and the host structure in order to assure permanent mechanical coupling between both elements, thus avoiding losses due to sliding.…”

Section: Examples Of Psa Tape-based Optical Sensorsmentioning

confidence: 99%

“…In particular, the symmetric S0 or antisymmetric A0 Lamb waves are coupled to guided L01 waves in an optical fiber at the adhesive bond location, resulting in L01 modes of equal amplitudes propagating in both directions along the optical fiber. Wee et al [ 104 ] demonstrated that when the adhesive bond is replaced with adhesive tape the S0 Lamb waves couple to the L01 modes with a preferential direction. The directional coupling that is produced by the adhesive tape could be applied to design multiplexed FBG sensor arrays with specified signal pathways through the optical fiber networks.…”

Section: Examples Of Psa Tape-based Optical Sensorsmentioning

confidence: 99%

Pressure Sensitive Adhesive Tape: A Versatile Material Platform for Optical Sensors

Barrios

2020

Pressure sensitive adhesive (PSA) tapes are a versatile, safe and easy-to-use solution for fastening, sealing, masking, or joining. They are widely employed in daily life, from domestic use to industrial applications in sectors such as construction and the automotive industry. In recent years, PSA tapes have found a place in the field of micro- and nanotechnology, particularly in contact transfer techniques where they can be used as either sacrificial layers or flexible substrates. As a consequence, various optical sensing configurations based on PSA tapes have been developed. In this paper, recent achievements related to the use of PSA tapes as functional and integral parts of optical sensors are reviewed. These include refractive index sensors, optomechanical sensors and vapor sensors.

“…Lamb waves can be actively generated in the structure using small actuators, and their propagation is altered due to the presence of damage in a structure. One common example of a detector is an optical fiber Bragg grating (FBG) sensor [ 4 ]. One benefit of using FBG sensors is that multiple sensors can be multiplexed along a single fiber so that many sensing locations can be provided with only one lead-in and -out connection [ 5 ].…”

Section: Introductionmentioning

confidence: 99%

Amplifying Lamb Wave Detection for Fiber Bragg Grating with a Phononic Crystal GRIN Lens Waveguide

Wang

Wee

Peters

2022

Self Cite

This paper demonstrates that a graded-index (GRIN) phononic lens, combined with a channel waveguide, can focus anti-symmetric Lamb waves for extraction by a detector with strong directional sensitivity. Guided ultrasonic wave inspection is commonly applied for structural health monitoring applications; however, obtaining sufficient signal amplitude is a challenge. In addition, fiber Bragg grating (FBG) sensors have strong directional sensitivity. We fabricate the GRIN structure, followed by a channel waveguide starting at the focal point, using a commercial 3D printer and mount it on a thin aluminum plate. We characterize the focusing of the A0 mode Lamb wave in the plate, traveling across the GRIN lens using 3D laser Doppler vibrometry. We also measure the extraction of focused energy using an FBG sensor, examining the optimal sensor bond location and bond length in the channel of the waveguide for maximum signal extraction. The measured amplification of the ultrasound signal is compared to theoretical predictions. The results demonstrate that significant amplification of the waveform is achieved and that selecting the location of the FBG sensor in the channel is critical to optimizing the amplification.