Embedded fiber Bragg grating sensor for internal strain measurements in polymeric materials

Botsis, J.; Humbert, Laurent; Colpo, F.; Giaccari, Ph.

doi:10.1016/j.optlaseng.2004.04.009

Cited by 109 publications

(73 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Another advantage of this FBG method is that the outcome is independent of the geometry of the sample and of the thermal profile set for its curing. Many authors applied this method for the 'health monitoring' of composite structures [1][2][3][4][5][6][7]. Further studies aim at the use of fibre optical technique to characterize cure of resins [8][9][10][11][12][13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Strain development in a filled epoxy resin curing under constrained and unconstrained conditions as assessed by Fibre Bragg Grating sensors

Harsch¹,

Karger‐Kocsis²,

Herzog³

2007

Express Polym. Lett.

View full text Add to dashboard Cite

Abstract. The influence of adhesion to the mould wall on the released strain of a highly filled anhydride cured epoxy resin (EP), which was hardened in an aluminium mould under constrained and unconstrained condition, was investigated. The shrinkage-induced strain was measured by fibre optical sensing technique. Fibre Bragg Grating (FBG) sensors were embedded into the curing EP placed in a cylindrical mould cavity. The cure-induced strain signals were detected in both, vertical and horizontal directions, during isothermal curing at 75°C for 1000 minutes. A huge difference in the strain signal of both directions could be detected for the different adhesion conditions. Under non-adhering condition the horizontal and vertical strain-time traces were practically identical resulting in a compressive strain at the end of about 3200 ppm, which is a proof of free or isotropic shrinking. However, under constrained condition the horizontal shrinkage in the EP was prevented due to its adhesion to the mould wall. So, the curing material shrunk preferably in vertical direction. This resulted in much higher released compressive strain signals in vertical (10 430 ppm) than in horizontal (2230 ppm) direction. The constrained cured EP resins are under inner stresses. Qualitative information on the residual stress state in the molding was deduced by exploiting the birefringence of the EP.

show abstract

Section: Introductionmentioning

confidence: 99%

Strain development in a filled epoxy resin curing under constrained and unconstrained conditions as assessed by Fibre Bragg Grating sensors

Harsch¹,

Karger‐Kocsis²,

Herzog³

2007

Express Polym. Lett.

View full text Add to dashboard Cite

show abstract

“…In order to overcome this problem the authors either suggest increasing the dataset by including more sensors and specimens in the experiments, or to make the damaged output independent from its original shape. It has been already discussed in the literature that embedding FBGs between composite layers could impose a residual strain distribution along the length of the FBG [19][20][21] . Therefore there would be a bias in the results of the classifications, because of these initial conditions.…”

Section: Discussionmentioning

confidence: 99%

Classification of composite damage from FBG load monitoring signals

et al. 2017

View full text Add to dashboard Cite

This paper describes a new method for the classification and identification of two major types of defects in composites, namely delamination and matrix cracks, by classification of the spectral features of fibre Bragg grating (FBG) signals. In aeronautical applications of composites, after a damage is detected, it is very useful to know the type of damage prior to determining the treatment method of the area or perhaps replacing the part. This was achieved by embedding FBG sensors inside a glass-fibre composite, and analysing the output signal from the sensors. The glass-fibre coupons were subjected to mode-I loading under tension-compression and static tests, in order to induce matrix cracks and delamination damages respectively. Afterwards, using wavelet features extracted from spectral measurements of the FBG sensors, classification of the damage type was carried out by means of support vector machines as a general classification tool with a quadratic kernel.

show abstract

“…Due to anisotropy or inhomogeneity of materials such as composites, the measurement of microscopic deformation within the structure is of interest for providing new information about the internal structural behavior under loading. So far, embedded fiber Bragg grating (FBG) sensors [5,6] have been proved to be well suited for accurate, localized, or distributed strain measurement in composite structures. However a major problem is that this type of technique is not able to provide a full field view of the strain distribution within the material.…”

Section: Introductionmentioning

confidence: 99%

Optical coherence elastography for measuring the deformation within glass fiber composite

2014

View full text Add to dashboard Cite

Optical coherence elastography (OCE) has been applied to the study of microscopic deformation in biological tissue under compressive stress for more than a decade. In this paper, OCE has been extended for the first time, to the best of our knowledge, to deformation measurement in a glass fiber composite in the field of nondestructive testing. A customized optical coherence tomography system, combined with a mechanical loading setup, was developed to provide pairs of prestressed and stressed structural images. The speckle tracking algorithm, based on 2D cross correlation, was used to estimate the local displacements in micrometer scale. The algorithm was first evaluated by a test of rigid body translation. Then the experiments were carried out with the tensile test and three point bending on a set of glass fiber composites. The structural features and structural variations during the mechanical loadings are clearly observed with the presented displacement maps. The advantages and prospects for OCE application on glass fiber composites are discussed at the end of this paper.

show abstract

Embedded fiber Bragg grating sensor for internal strain measurements in polymeric materials

Cited by 109 publications

References 25 publications

Strain development in a filled epoxy resin curing under constrained and unconstrained conditions as assessed by Fibre Bragg Grating sensors

Strain development in a filled epoxy resin curing under constrained and unconstrained conditions as assessed by Fibre Bragg Grating sensors

Classification of composite damage from FBG load monitoring signals

Optical coherence elastography for measuring the deformation within glass fiber composite

Contact Info

Product

Resources

About