Acousto-ultrasonic sensing using fiber Bragg gratings

Betz, Daniel; Thursby, Graham; Culshaw, Brian; Staszewski, Wiesław J.

doi:10.1088/0964-1726/12/1/314

Cited by 243 publications

(161 citation statements)

References 16 publications

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“…The research methods concentrated on computer simulation with finite element model (FEM) mostly. Betz et al (2003) studied strain transferring of patch bonded FBG sensors with finite element analysis and experiments. The fiber is first placed on a backing patch and this patch is simply glued to the surface of a structure.…”

Section: Strain Transferring Mechanism For Surface-bonded Ofssmentioning

confidence: 99%

Mechanical Property and Strain Transferring Mechanism in Optical Fiber Sensors

Li¹,

Ren²,

Li³

2012

Fiber Optic Sensors

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Section: Strain Transferring Mechanism For Surface-bonded Ofssmentioning

confidence: 99%

Mechanical Property and Strain Transferring Mechanism in Optical Fiber Sensors

Li¹,

Ren²,

Li³

2012

Fiber Optic Sensors

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“…The direction of propagation of an acoustic wave arriving at a rosette can be determined from the relative amplitudes of the signals obtained from each of the 3 gratings. Calculating the point of intersection of the direction given by the 2 rosettes gives a point, which is the source of the acoustic wave [4]. In order to determine the location of the damage it is …”

Section: Experimental Damage Detectionmentioning

confidence: 99%

The Use of Fibre Optic Sensors for Damage Detection and Location in Structural Materials

Thursby

Sorazu²,

Betz³

et al. 2004

AMM

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Abstract. The measurement of changes in the properties of ultrasonic Lamb waves propagating through structural material has frequently been proposed as a method for the detection of damage. In this paper we describe work that uses optical fibre sensors to detect the Lamb waves and show that the directional properties of these sensors allow us to not only detect damage, but also to locate it.We look at two types of optical fibre sensor, a polarimetric sensor and the fibre Bragg grating. The polarimetric sensor measures the change in birefringence of a fibre caused by the pressure wave of the ultrasound acting upon it. This is an integrated sensor since the fibre length bonded to the sample needs to be greater than the ultrasonic wavelength in order to obtain the required sensitivity. The maximum sensitivity of this sensor is when the fibre is positioned normal to the direction of wave propagation. Fibre Bragg gratings are essentially point sensors since the grating length needs to be a fraction of the ultrasound wavelength to obtain maximum sensitivity. Ultrasound is detected mainly through the in-plane strain it produces and maximum sensitivity is therefore produced when the grating is aligned parallel to the direction of wave propagation.Holes drilled into sample plates can be detected using both type of sensor by examining the changes in either the transmitted Lamb wave or through detection of the reflections produced by the hole. The sensitivity of the technique is shown to be determined by the relative positions of the acoustic source, the hole and the sensor. If we use fibre Bragg gratings in a rosette configuration (i.e. 3 gratings forming an equilateral triangle) then the direction of the Lamb wave can be determined using the directional sensitivities of the gratings. Using two such rosettes allows us to calculate the source of the wave from the intersection of two of these directions. If the source of the wave is the hole (which acts as a passive source), then the location of that hole can be determined.

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“…The fibres are of minimal diameter (40-250 µm) [28], allowing them to be embedded within composite materials and used to monitor both the temperature and strain applied to a structure, by measuring variations in the local strain field [29]. Fibre optic sensors have been shown to be capable of detecting delaminations, but require complex and typically heavy equipment to interrogate them, and unless used in combination with piezoelectric transducers (used to generate ultrasonic waves) [30,31,32], an extremely high density network of optical fibres would be required to detect impact damage in a large composite structure. Alternative systems based on measuring variations in the electrical resistance between embedded electrodes, have displayed the capability to detect impact damage in composites reinforced with conductive carbon fibres [33,34].…”

Section: Introductionmentioning

confidence: 99%

Monitoring cure and detecting damage in composites with inductively coupled embedded sensors

Chilles

Koutsomitopoulou

Croxford

et al. 2016

Composites Science and Technology

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. February 2016Abstract. This paper demonstrates the capability of embedded piezoelectric sensors to monitor the state of health throughout the lifetime of composite structures. Sensors were embedded into fibre reinforced composites and used to monitor the progress of cure during manufacture, and the subsequent damage state of the cured part. The sensors used in this work consist of a single piezoelectric transducer, which is electronically connected to an inductance coil. A probe containing two inductance coils was used to make wireless ultrasonic measurements. When the probe was placed in close proximity to an embedded sensor, the electromagnetic coupling between the coils in probe and the embedded coil, allowed electronic signals to be wirelessly transferred between the transducer and the ultrasonic processing equipment. Two different inductively coupled transducer systems (ICTS) were used to monitor cure. A ICTS which generated bulk waves monitored the cure of a thick glass fibre section, and an ICTS which generated guided elastic waves monitored the cure of a large glass fibre plate. To characterise the cure monitoring ability of each ICTS, two established cure monitoring techniques; differential scanning calorimetry (DSC) and dielectric analysis, were used to record measurements during cure. The guided wave ICTS was then used to detect barely visible impact damage (BVID), created by a 10 Joule impact at a distance of 300 mm from the sensor embedded in the large glass fibre plate.

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Acousto-ultrasonic sensing using fiber Bragg gratings

Cited by 243 publications

References 16 publications

Mechanical Property and Strain Transferring Mechanism in Optical Fiber Sensors

Mechanical Property and Strain Transferring Mechanism in Optical Fiber Sensors

The Use of Fibre Optic Sensors for Damage Detection and Location in Structural Materials

Monitoring cure and detecting damage in composites with inductively coupled embedded sensors

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