Sensitivity of embedded fibre optic Bragg grating sensors to disbonds in bonded composite ship joints

Li, H.C.H.; Herszberg, Israel; Mouritz, A.P.; Davis, Claire; Galea, Steve C

doi:10.1016/j.compstruct.2004.04.045

Cited by 37 publications

(15 citation statements)

References 4 publications

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“…It is important to note that if the reference sensor is positioned on or near the same plane as that of the damage, then the sensing location must be chosen such that the disbond must be close (within 5 mm) to the sensor at its critical (warning triggering) length without having propagated past it. This is because it has been shown that the growth of a disbond past a Bragg grating strain sensor in the same plane significantly altered the reflection profile, which would render it unsuitable for use as a reference sensor 4 . In this study, interrogation point A may be used to detect disbond damage up 12 mm in length.…”

Section: Finite Element Analysismentioning

confidence: 99%

Health monitoring of bonded composite repairs using fibre optic sensors

Dupouy²,

Herszberg³

et al. 2006

SPIE Proceedings

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Structural health monitoring (SHM) technology may be applied to composite bonded repairs to enable the continuous through-life assessment of the repair efficacy. This paper describes an SHM technique for the detection of debonding in composite bonded patches using fibre optic Bragg grating strain sensors. A two sided doubler repair is examined in this paper. A finite element study was conducted which showed that the strain in the debonded region changed significantly compared to the undamaged state. A differential strain approach was used to facilitate the detection of debonds, where two sensors were strategically positioned so that their strain differential increased with the disbond length. With the use of matching gratings, this technique greatly reduces the interrogation equipment requirement by converting spectral information into an intensity-modulated signal, thus allowing a threshold value to be set to indicate imminent critical repair failure. An experimental investigation was conducted, using carbon/epoxy patches to carbon/epoxy substrates, to validate the theoretically predicted results. The experimental measurements agreed well with the numerical findings, indicating that the proposed scheme has great potential as a simple monitoring technique for composite bonded repairs.

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Section: Finite Element Analysismentioning

confidence: 99%

Health monitoring of bonded composite repairs using fibre optic sensors

Dupouy²,

Herszberg³

et al. 2006

SPIE Proceedings

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“…AE and optical-fibre sensing are passive forms of in situ structural health monitoring, as no additional excitation is applied to the structure other than the operational load. Various researchers (Davis et al 2002;Li 2004) have shown that the occurrence of damage in a structure alters the local strain distribution under structural load due to the changing load path. Thus, the occurrence and extent of damage could be detected when the measured strain at a given location significantly diverges from the value expected for a healthy structure.…”

Section: Optical-fibre Sensingmentioning

confidence: 99%

Failure investigation of top-hat composite stiffened panels

Prusty¹,

Raju²

2013

Ships and Offshore Structures

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This paper presents a study on failure investigation of top-hat composite stiffened panels using a combination of techniques. Acoustic emission technique is used to discriminate between the various failure modes using piezoelectric sensors. In addition, an attempt is made to investigate the possibility of using a state of the art surfaced bonded fibre-optic sensor as an acoustic sensor. A strain insensitive fibre Bragg grating (FBG) sensor is used to compare the performance of piezoelectric sensors for composite structures. On the other hand, fibre-optic sensors have some beneficial properties such as low specific weight, small size and good compatibility with polymeric composites compared to traditional sensing mechanisms. FBG sensors are expected to provide a replacement for traditional electric sensors as FBGs are not susceptible to electromagnetic signature, have multi-functionality and enable multiplexing. Fibre-optic sensors are embedded in the composite specimen to measure the non-linear strain at the bend and to analyse the progressive failure with strain anomalies.

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“…These sensors can be used to monitor both strain and damage development [9][10][11][12]. Such sensors are also finding applications for internal strain monitoring in composite ship structures and patch repairs [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%