Abstract

Stress-induced birefringence can lead to distortion in the reflection spectra of fiber Bragg grating (FBG) sensors, thereby resulting in the loss of accuracy and stability of strain measurements. The bonding layer is a direct factor in producing stress birefringence within FBGs. To assess the impacts quantitatively, a theoretical model that links the bonding layer and the reflection spectrum was established. At the same time, the finite element method, based on the theoretical model, was used to study the relationships between characteristics of the bonding layer and reflection spectrum in detail. The analytical results indicate that high elastic modulus and mismatched Poisson’s ratio of bonding layer decrease the available strain measuring range of FBGs remarkably, and that unreasonable geometric parameters of the bonding layer should be avoided. In addition, a validation experiment was conducted and experimental results proved the prediction of the theoretical analysis. It can be concluded from the results that the bonding layer is the major limiting factor for the application of surface-bonded FBG sensors in large strain measurements. The bonding materials and bonding processes used in producing FBG sensors deserve serious consideration.

© 2014 Optical Society of America

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References

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  1. P. Moyo, J. M. W. Brownjohn, R. Suresh, and S. C. Tjin, “Development of fiber Bragg grating sensors for monitoring civil infrastructure,” Eng. Struct. 27, 1828–1834 (2005).
    [CrossRef]
  2. A. Mendez, “Fiber Bragg grating sensors: a market overview,” Proc. SPIE 6619, 661905 (2007).
    [CrossRef]
  3. F. Surre, R. H. Scott, P. Banerji, P. A. M. Basheer, T. Sun, and K. T. V. Grattana, “Study of reliability of fibre Bragg grating fibre optic strain sensors for field-test applications,” Sens. Actuators A 185, 8–16 (2012).
    [CrossRef]
  4. Y. B. Lin, K. C. Chang, J. C. Chern, and L. A. Wang, “Packaging methods of fiber-Bragg grating sensors in civil structure applications,” IEEE Sens. J. 5, 419–424 (2005).
    [CrossRef]
  5. W. Y. Li, C. C. Cheng, and Y. L. Lo, “Investigation of strain transmission of surface-bonded FBGs used as strain sensors,” Sens. Actuators A 149, 201–207 (2009).
    [CrossRef]
  6. K. T. Wan, C. K. Y. Leung, and N. G. Olson, “Investigation of the strain transfer for surface-attached optical fiber strain sensors,” Smart Mater. Struct. 17, 035037 (2008).
    [CrossRef]
  7. Q. B. Wang, Y. Qiu, H. T. Zhao, J. A. Chen, Y. Y. Wang, and Z. M. Fan, “Analysis of strain transfer of six-layer surface-bonded fiber Bragg gratings,” Appl. Opt. 51, 4129–4138 (2012).
    [CrossRef]
  8. H. Storoy and K. Johannessen, “Glue induced birefringence in surface mounted optical fibres,” Electron. Lett. 33, 800–801 (1997).
    [CrossRef]
  9. J. R. Lee, H. Tsuda, and B. Y. Koo, “Single-mode fibre optic Bragg grating sensing on the base of birefringence in surface-mounting and embedding applications,” Opt. Laser Technol. 39, 157–164 (2007).
    [CrossRef]
  10. C. C. Cheng, Y. L. Lo, and W. Y. Li, “Accurate simulations of reflective wavelength spectrum of surface-bonded fiber Bragg grating,” Appl. Opt. 49, 3394–3402 (2010).
    [CrossRef]
  11. R. Gafsi and M. A. El-Sherif, “Analysis of induced-birefringence effects on fiber Bragg gratings,” Opt. Fiber Technol. 6, 299–323 (2000).
    [CrossRef]
  12. J. M. Menendez and J. A. Guemes, “Bragg grating-based multiaxial strain sensing: its application to residual strain measurement in composite laminates,” Proc. SPIE 3986, 271–281 (2000).
    [CrossRef]
  13. A. P. Zhang, B. O. Guan, X. M. Tao, and H. Y. Tam, “Experimental and theoretical analysis of fiber Bragg gratings under lateral compression,” Opt. Commun. 206, 81–87 (2002).
    [CrossRef]
  14. A. Othonos, “Fiber Bragg gratings,” Rev. Sci. Instrum. 68, 4309–4341 (1997).
    [CrossRef]
  15. W. M. Chen, J. Wu, P. Zhang, L. Liu, and H. Liu, “Metallized bonding technology of fiber Bragg grating strain sensor,” Sens. Lett. 10, 1474–1477 (2012).
    [CrossRef]
  16. H. Liu, W. M. Chen, P. Zhang, J. Wu, and L. Liu, “Optimization for metal bonding technology of optical fiber sensor,” Proc. SPIE 8199, 819910 (2011).
    [CrossRef]

2012 (3)

F. Surre, R. H. Scott, P. Banerji, P. A. M. Basheer, T. Sun, and K. T. V. Grattana, “Study of reliability of fibre Bragg grating fibre optic strain sensors for field-test applications,” Sens. Actuators A 185, 8–16 (2012).
[CrossRef]

Q. B. Wang, Y. Qiu, H. T. Zhao, J. A. Chen, Y. Y. Wang, and Z. M. Fan, “Analysis of strain transfer of six-layer surface-bonded fiber Bragg gratings,” Appl. Opt. 51, 4129–4138 (2012).
[CrossRef]

W. M. Chen, J. Wu, P. Zhang, L. Liu, and H. Liu, “Metallized bonding technology of fiber Bragg grating strain sensor,” Sens. Lett. 10, 1474–1477 (2012).
[CrossRef]

2011 (1)

H. Liu, W. M. Chen, P. Zhang, J. Wu, and L. Liu, “Optimization for metal bonding technology of optical fiber sensor,” Proc. SPIE 8199, 819910 (2011).
[CrossRef]

2010 (1)

2009 (1)

W. Y. Li, C. C. Cheng, and Y. L. Lo, “Investigation of strain transmission of surface-bonded FBGs used as strain sensors,” Sens. Actuators A 149, 201–207 (2009).
[CrossRef]

2008 (1)

K. T. Wan, C. K. Y. Leung, and N. G. Olson, “Investigation of the strain transfer for surface-attached optical fiber strain sensors,” Smart Mater. Struct. 17, 035037 (2008).
[CrossRef]

2007 (2)

A. Mendez, “Fiber Bragg grating sensors: a market overview,” Proc. SPIE 6619, 661905 (2007).
[CrossRef]

J. R. Lee, H. Tsuda, and B. Y. Koo, “Single-mode fibre optic Bragg grating sensing on the base of birefringence in surface-mounting and embedding applications,” Opt. Laser Technol. 39, 157–164 (2007).
[CrossRef]

2005 (2)

P. Moyo, J. M. W. Brownjohn, R. Suresh, and S. C. Tjin, “Development of fiber Bragg grating sensors for monitoring civil infrastructure,” Eng. Struct. 27, 1828–1834 (2005).
[CrossRef]

Y. B. Lin, K. C. Chang, J. C. Chern, and L. A. Wang, “Packaging methods of fiber-Bragg grating sensors in civil structure applications,” IEEE Sens. J. 5, 419–424 (2005).
[CrossRef]

2002 (1)

A. P. Zhang, B. O. Guan, X. M. Tao, and H. Y. Tam, “Experimental and theoretical analysis of fiber Bragg gratings under lateral compression,” Opt. Commun. 206, 81–87 (2002).
[CrossRef]

2000 (2)

R. Gafsi and M. A. El-Sherif, “Analysis of induced-birefringence effects on fiber Bragg gratings,” Opt. Fiber Technol. 6, 299–323 (2000).
[CrossRef]

J. M. Menendez and J. A. Guemes, “Bragg grating-based multiaxial strain sensing: its application to residual strain measurement in composite laminates,” Proc. SPIE 3986, 271–281 (2000).
[CrossRef]

1997 (2)

A. Othonos, “Fiber Bragg gratings,” Rev. Sci. Instrum. 68, 4309–4341 (1997).
[CrossRef]

H. Storoy and K. Johannessen, “Glue induced birefringence in surface mounted optical fibres,” Electron. Lett. 33, 800–801 (1997).
[CrossRef]

Banerji, P.

F. Surre, R. H. Scott, P. Banerji, P. A. M. Basheer, T. Sun, and K. T. V. Grattana, “Study of reliability of fibre Bragg grating fibre optic strain sensors for field-test applications,” Sens. Actuators A 185, 8–16 (2012).
[CrossRef]

Basheer, P. A. M.

F. Surre, R. H. Scott, P. Banerji, P. A. M. Basheer, T. Sun, and K. T. V. Grattana, “Study of reliability of fibre Bragg grating fibre optic strain sensors for field-test applications,” Sens. Actuators A 185, 8–16 (2012).
[CrossRef]

Brownjohn, J. M. W.

P. Moyo, J. M. W. Brownjohn, R. Suresh, and S. C. Tjin, “Development of fiber Bragg grating sensors for monitoring civil infrastructure,” Eng. Struct. 27, 1828–1834 (2005).
[CrossRef]

Chang, K. C.

Y. B. Lin, K. C. Chang, J. C. Chern, and L. A. Wang, “Packaging methods of fiber-Bragg grating sensors in civil structure applications,” IEEE Sens. J. 5, 419–424 (2005).
[CrossRef]

Chen, J. A.

Chen, W. M.

W. M. Chen, J. Wu, P. Zhang, L. Liu, and H. Liu, “Metallized bonding technology of fiber Bragg grating strain sensor,” Sens. Lett. 10, 1474–1477 (2012).
[CrossRef]

H. Liu, W. M. Chen, P. Zhang, J. Wu, and L. Liu, “Optimization for metal bonding technology of optical fiber sensor,” Proc. SPIE 8199, 819910 (2011).
[CrossRef]

Cheng, C. C.

C. C. Cheng, Y. L. Lo, and W. Y. Li, “Accurate simulations of reflective wavelength spectrum of surface-bonded fiber Bragg grating,” Appl. Opt. 49, 3394–3402 (2010).
[CrossRef]

W. Y. Li, C. C. Cheng, and Y. L. Lo, “Investigation of strain transmission of surface-bonded FBGs used as strain sensors,” Sens. Actuators A 149, 201–207 (2009).
[CrossRef]

Chern, J. C.

Y. B. Lin, K. C. Chang, J. C. Chern, and L. A. Wang, “Packaging methods of fiber-Bragg grating sensors in civil structure applications,” IEEE Sens. J. 5, 419–424 (2005).
[CrossRef]

El-Sherif, M. A.

R. Gafsi and M. A. El-Sherif, “Analysis of induced-birefringence effects on fiber Bragg gratings,” Opt. Fiber Technol. 6, 299–323 (2000).
[CrossRef]

Fan, Z. M.

Gafsi, R.

R. Gafsi and M. A. El-Sherif, “Analysis of induced-birefringence effects on fiber Bragg gratings,” Opt. Fiber Technol. 6, 299–323 (2000).
[CrossRef]

Grattana, K. T. V.

F. Surre, R. H. Scott, P. Banerji, P. A. M. Basheer, T. Sun, and K. T. V. Grattana, “Study of reliability of fibre Bragg grating fibre optic strain sensors for field-test applications,” Sens. Actuators A 185, 8–16 (2012).
[CrossRef]

Guan, B. O.

A. P. Zhang, B. O. Guan, X. M. Tao, and H. Y. Tam, “Experimental and theoretical analysis of fiber Bragg gratings under lateral compression,” Opt. Commun. 206, 81–87 (2002).
[CrossRef]

Guemes, J. A.

J. M. Menendez and J. A. Guemes, “Bragg grating-based multiaxial strain sensing: its application to residual strain measurement in composite laminates,” Proc. SPIE 3986, 271–281 (2000).
[CrossRef]

Johannessen, K.

H. Storoy and K. Johannessen, “Glue induced birefringence in surface mounted optical fibres,” Electron. Lett. 33, 800–801 (1997).
[CrossRef]

Koo, B. Y.

J. R. Lee, H. Tsuda, and B. Y. Koo, “Single-mode fibre optic Bragg grating sensing on the base of birefringence in surface-mounting and embedding applications,” Opt. Laser Technol. 39, 157–164 (2007).
[CrossRef]

Lee, J. R.

J. R. Lee, H. Tsuda, and B. Y. Koo, “Single-mode fibre optic Bragg grating sensing on the base of birefringence in surface-mounting and embedding applications,” Opt. Laser Technol. 39, 157–164 (2007).
[CrossRef]

Leung, C. K. Y.

K. T. Wan, C. K. Y. Leung, and N. G. Olson, “Investigation of the strain transfer for surface-attached optical fiber strain sensors,” Smart Mater. Struct. 17, 035037 (2008).
[CrossRef]

Li, W. Y.

C. C. Cheng, Y. L. Lo, and W. Y. Li, “Accurate simulations of reflective wavelength spectrum of surface-bonded fiber Bragg grating,” Appl. Opt. 49, 3394–3402 (2010).
[CrossRef]

W. Y. Li, C. C. Cheng, and Y. L. Lo, “Investigation of strain transmission of surface-bonded FBGs used as strain sensors,” Sens. Actuators A 149, 201–207 (2009).
[CrossRef]

Lin, Y. B.

Y. B. Lin, K. C. Chang, J. C. Chern, and L. A. Wang, “Packaging methods of fiber-Bragg grating sensors in civil structure applications,” IEEE Sens. J. 5, 419–424 (2005).
[CrossRef]

Liu, H.

W. M. Chen, J. Wu, P. Zhang, L. Liu, and H. Liu, “Metallized bonding technology of fiber Bragg grating strain sensor,” Sens. Lett. 10, 1474–1477 (2012).
[CrossRef]

H. Liu, W. M. Chen, P. Zhang, J. Wu, and L. Liu, “Optimization for metal bonding technology of optical fiber sensor,” Proc. SPIE 8199, 819910 (2011).
[CrossRef]

Liu, L.

W. M. Chen, J. Wu, P. Zhang, L. Liu, and H. Liu, “Metallized bonding technology of fiber Bragg grating strain sensor,” Sens. Lett. 10, 1474–1477 (2012).
[CrossRef]

H. Liu, W. M. Chen, P. Zhang, J. Wu, and L. Liu, “Optimization for metal bonding technology of optical fiber sensor,” Proc. SPIE 8199, 819910 (2011).
[CrossRef]

Lo, Y. L.

C. C. Cheng, Y. L. Lo, and W. Y. Li, “Accurate simulations of reflective wavelength spectrum of surface-bonded fiber Bragg grating,” Appl. Opt. 49, 3394–3402 (2010).
[CrossRef]

W. Y. Li, C. C. Cheng, and Y. L. Lo, “Investigation of strain transmission of surface-bonded FBGs used as strain sensors,” Sens. Actuators A 149, 201–207 (2009).
[CrossRef]

Mendez, A.

A. Mendez, “Fiber Bragg grating sensors: a market overview,” Proc. SPIE 6619, 661905 (2007).
[CrossRef]

Menendez, J. M.

J. M. Menendez and J. A. Guemes, “Bragg grating-based multiaxial strain sensing: its application to residual strain measurement in composite laminates,” Proc. SPIE 3986, 271–281 (2000).
[CrossRef]

Moyo, P.

P. Moyo, J. M. W. Brownjohn, R. Suresh, and S. C. Tjin, “Development of fiber Bragg grating sensors for monitoring civil infrastructure,” Eng. Struct. 27, 1828–1834 (2005).
[CrossRef]

Olson, N. G.

K. T. Wan, C. K. Y. Leung, and N. G. Olson, “Investigation of the strain transfer for surface-attached optical fiber strain sensors,” Smart Mater. Struct. 17, 035037 (2008).
[CrossRef]

Othonos, A.

A. Othonos, “Fiber Bragg gratings,” Rev. Sci. Instrum. 68, 4309–4341 (1997).
[CrossRef]

Qiu, Y.

Scott, R. H.

F. Surre, R. H. Scott, P. Banerji, P. A. M. Basheer, T. Sun, and K. T. V. Grattana, “Study of reliability of fibre Bragg grating fibre optic strain sensors for field-test applications,” Sens. Actuators A 185, 8–16 (2012).
[CrossRef]

Storoy, H.

H. Storoy and K. Johannessen, “Glue induced birefringence in surface mounted optical fibres,” Electron. Lett. 33, 800–801 (1997).
[CrossRef]

Sun, T.

F. Surre, R. H. Scott, P. Banerji, P. A. M. Basheer, T. Sun, and K. T. V. Grattana, “Study of reliability of fibre Bragg grating fibre optic strain sensors for field-test applications,” Sens. Actuators A 185, 8–16 (2012).
[CrossRef]

Suresh, R.

P. Moyo, J. M. W. Brownjohn, R. Suresh, and S. C. Tjin, “Development of fiber Bragg grating sensors for monitoring civil infrastructure,” Eng. Struct. 27, 1828–1834 (2005).
[CrossRef]

Surre, F.

F. Surre, R. H. Scott, P. Banerji, P. A. M. Basheer, T. Sun, and K. T. V. Grattana, “Study of reliability of fibre Bragg grating fibre optic strain sensors for field-test applications,” Sens. Actuators A 185, 8–16 (2012).
[CrossRef]

Tam, H. Y.

A. P. Zhang, B. O. Guan, X. M. Tao, and H. Y. Tam, “Experimental and theoretical analysis of fiber Bragg gratings under lateral compression,” Opt. Commun. 206, 81–87 (2002).
[CrossRef]

Tao, X. M.

A. P. Zhang, B. O. Guan, X. M. Tao, and H. Y. Tam, “Experimental and theoretical analysis of fiber Bragg gratings under lateral compression,” Opt. Commun. 206, 81–87 (2002).
[CrossRef]

Tjin, S. C.

P. Moyo, J. M. W. Brownjohn, R. Suresh, and S. C. Tjin, “Development of fiber Bragg grating sensors for monitoring civil infrastructure,” Eng. Struct. 27, 1828–1834 (2005).
[CrossRef]

Tsuda, H.

J. R. Lee, H. Tsuda, and B. Y. Koo, “Single-mode fibre optic Bragg grating sensing on the base of birefringence in surface-mounting and embedding applications,” Opt. Laser Technol. 39, 157–164 (2007).
[CrossRef]

Wan, K. T.

K. T. Wan, C. K. Y. Leung, and N. G. Olson, “Investigation of the strain transfer for surface-attached optical fiber strain sensors,” Smart Mater. Struct. 17, 035037 (2008).
[CrossRef]

Wang, L. A.

Y. B. Lin, K. C. Chang, J. C. Chern, and L. A. Wang, “Packaging methods of fiber-Bragg grating sensors in civil structure applications,” IEEE Sens. J. 5, 419–424 (2005).
[CrossRef]

Wang, Q. B.

Wang, Y. Y.

Wu, J.

W. M. Chen, J. Wu, P. Zhang, L. Liu, and H. Liu, “Metallized bonding technology of fiber Bragg grating strain sensor,” Sens. Lett. 10, 1474–1477 (2012).
[CrossRef]

H. Liu, W. M. Chen, P. Zhang, J. Wu, and L. Liu, “Optimization for metal bonding technology of optical fiber sensor,” Proc. SPIE 8199, 819910 (2011).
[CrossRef]

Zhang, A. P.

A. P. Zhang, B. O. Guan, X. M. Tao, and H. Y. Tam, “Experimental and theoretical analysis of fiber Bragg gratings under lateral compression,” Opt. Commun. 206, 81–87 (2002).
[CrossRef]

Zhang, P.

W. M. Chen, J. Wu, P. Zhang, L. Liu, and H. Liu, “Metallized bonding technology of fiber Bragg grating strain sensor,” Sens. Lett. 10, 1474–1477 (2012).
[CrossRef]

H. Liu, W. M. Chen, P. Zhang, J. Wu, and L. Liu, “Optimization for metal bonding technology of optical fiber sensor,” Proc. SPIE 8199, 819910 (2011).
[CrossRef]

Zhao, H. T.

Appl. Opt. (2)

Electron. Lett. (1)

H. Storoy and K. Johannessen, “Glue induced birefringence in surface mounted optical fibres,” Electron. Lett. 33, 800–801 (1997).
[CrossRef]

Eng. Struct. (1)

P. Moyo, J. M. W. Brownjohn, R. Suresh, and S. C. Tjin, “Development of fiber Bragg grating sensors for monitoring civil infrastructure,” Eng. Struct. 27, 1828–1834 (2005).
[CrossRef]

IEEE Sens. J. (1)

Y. B. Lin, K. C. Chang, J. C. Chern, and L. A. Wang, “Packaging methods of fiber-Bragg grating sensors in civil structure applications,” IEEE Sens. J. 5, 419–424 (2005).
[CrossRef]

Opt. Commun. (1)

A. P. Zhang, B. O. Guan, X. M. Tao, and H. Y. Tam, “Experimental and theoretical analysis of fiber Bragg gratings under lateral compression,” Opt. Commun. 206, 81–87 (2002).
[CrossRef]

Opt. Fiber Technol. (1)

R. Gafsi and M. A. El-Sherif, “Analysis of induced-birefringence effects on fiber Bragg gratings,” Opt. Fiber Technol. 6, 299–323 (2000).
[CrossRef]

Opt. Laser Technol. (1)

J. R. Lee, H. Tsuda, and B. Y. Koo, “Single-mode fibre optic Bragg grating sensing on the base of birefringence in surface-mounting and embedding applications,” Opt. Laser Technol. 39, 157–164 (2007).
[CrossRef]

Proc. SPIE (3)

J. M. Menendez and J. A. Guemes, “Bragg grating-based multiaxial strain sensing: its application to residual strain measurement in composite laminates,” Proc. SPIE 3986, 271–281 (2000).
[CrossRef]

A. Mendez, “Fiber Bragg grating sensors: a market overview,” Proc. SPIE 6619, 661905 (2007).
[CrossRef]

H. Liu, W. M. Chen, P. Zhang, J. Wu, and L. Liu, “Optimization for metal bonding technology of optical fiber sensor,” Proc. SPIE 8199, 819910 (2011).
[CrossRef]

Rev. Sci. Instrum. (1)

A. Othonos, “Fiber Bragg gratings,” Rev. Sci. Instrum. 68, 4309–4341 (1997).
[CrossRef]

Sens. Actuators A (2)

F. Surre, R. H. Scott, P. Banerji, P. A. M. Basheer, T. Sun, and K. T. V. Grattana, “Study of reliability of fibre Bragg grating fibre optic strain sensors for field-test applications,” Sens. Actuators A 185, 8–16 (2012).
[CrossRef]

W. Y. Li, C. C. Cheng, and Y. L. Lo, “Investigation of strain transmission of surface-bonded FBGs used as strain sensors,” Sens. Actuators A 149, 201–207 (2009).
[CrossRef]

Sens. Lett. (1)

W. M. Chen, J. Wu, P. Zhang, L. Liu, and H. Liu, “Metallized bonding technology of fiber Bragg grating strain sensor,” Sens. Lett. 10, 1474–1477 (2012).
[CrossRef]

Smart Mater. Struct. (1)

K. T. Wan, C. K. Y. Leung, and N. G. Olson, “Investigation of the strain transfer for surface-attached optical fiber strain sensors,” Smart Mater. Struct. 17, 035037 (2008).
[CrossRef]

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Figures (12)

Fig. 1.
Fig. 1.

(a) FBG subjected to the transversal force. (b) Cross-sectional view of FBG.

Fig. 2.
Fig. 2.

Comparison of typical spectrum and distorted spectrum caused by stress birefringence.

Fig. 3.
Fig. 3.

(a) Sketch diagram of the surface-bonded FBG and the deformation under stress. (b) Cross-sectional view of deformed FBG region (simplified to facilitate analysis).

Fig. 4.
Fig. 4.

Meshed finite element model of a surface-bonded FBG.

Fig. 5.
Fig. 5.

Evolution of the gap as a function of elastic modulus of bonding layer Eb (Poisson’s ratio of bonding layer, νb=0.33 thickness H=0.4mm, h=0.1375mm).

Fig. 6.
Fig. 6.

Evolution of the gap as a function of Poisson’s ratio of bonding layer νb (elastic modulus of bonding layer Eb=74.52GPa, thickness H=0.4mm, h=0.1375mm).

Fig. 7.
Fig. 7.

Evolution of the gap as a function of bottom thickness h (Poisson’s ratio of bonding layer νb=0.33, elastic modulus of bonding layer Eb=74.52GPa, thickness H=0.4mm).

Fig. 8.
Fig. 8.

Evolution of the gap as a function of bottom thickness h (Poisson’s ratio of bonding layer νb=0.33, elastic modulus of bonding layer Eb=74.52GPa, thickness h=0.05mm).

Fig. 9.
Fig. 9.

Evolution of reflection spectra caused by different bonding layers as functions of longitudinal strain.

Fig. 10.
Fig. 10.

Schematic diagram of the experimental system.

Fig. 11.
Fig. 11.

(a) Spectra of FBG bonded by zinc during loading. (b) Spectra of FBG bonded by zinc during unloading. (c) Spectra of FBG bonded by epoxy during loading. (d) Spectra of FBG bonded by epoxy during unloading.

Fig. 12.
Fig. 12.

3-dB bandwidth of spectra obtained by the experiment.

Tables (3)

Tables Icon

Table 1. Common Parameters Used for Calculations

Tables Icon

Table 2. Material Properties of Bonding Layers Used for Stimulation of Reflection Spectrum

Tables Icon

Table 3. Parameters and Fabrication Method of Specimen

Equations (7)

Equations on this page are rendered with MathJax. Learn more.

λB=2nΛ,
Δnx=n032EF{(p112νFp12)σx+[(1νF)p12νFp11](σy+σz)},
Δny=n032EF{(p112νFp12)σy+[(1νF)p12νFp11](σx+σz)},
Δλ=2Λ|ΔnxΔny|=Λn03EF[(1+νF)p11(1νF)p12]|(σxσy)|.
Λ=Λ0(1+εzcore)=Λ0(1+Kεz),
σx=1202π|σx(θ)|dθ,
σy=1202π|σy(θ)|dθ.

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