Effect of thermal residual stress on the reflection spectrum from FBG sensors embedded in CFRP composites

Yoji Okabe, Shigeki Yashiro, Ryohei Tsuji, Tadahito Mizutani, Nobuo Takeda

Research output: Contribution to journalConference article

3 Citations (Scopus)

Abstract

When fiber Bragg grating (FBG) sensors are embedded in carbon fiber reinforced plastic (CFRP) laminates, the reflection spectrum from the FBG sensors split into two peaks because of the non-axisymmetric thermal residual stress. This deformation of the spectrum will lead to misreading in strain measurements or crack detection in the laminates. In the present research, three types of FBG sensors: uncoated normal, polyimide-coated normal, and polyimide-coated small-diameter FBG sensors were embedded in CFRP laminates, and reflection spectra from the sensors were measured during the fabrication process of the laminates in order to evaluate the effect of thermal residual stress on the reflection spectra. Through the comparison of results obtained for the three FBG sensors, it was found that the effect of thermal residual stress on the reflection spectrum could be decreased when the optical fiber was coated with polyimide in the present laminate configuration and embedment position. Furthermore, these changes in the spectra during the curing process were simulated theoretically. Thermal residual stress components at the core were obtained by FEM analysis, and the spectra were calculated using the couple mode theory and the transfer matrix method. Considering the birefringence effect, the calculated spectra reproduced the measured spectra very well.

Original languageEnglish
Pages (from-to)59-68
Number of pages10
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume4704
DOIs
Publication statusPublished - Jan 1 2002
EventNondestructive Evaluation and Health Monitoring of Aerospace Materials and Civil Infrastructures - Newport Beach, CA, United States
Duration: Mar 18 2002Mar 19 2002

Fingerprint

carbon fiber reinforced plastics
Fiber Bragg Grating Sensor
Carbon Fiber
Thermal Stress
Carbon fiber reinforced plastics
Residual Stress
Fiber Bragg gratings
thermal stresses
Thermal stress
Bragg gratings
residual stress
Plastics
Residual stresses
Composite
Laminates
composite materials
fibers
sensors
Sensors
Composite materials

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Cite this

Effect of thermal residual stress on the reflection spectrum from FBG sensors embedded in CFRP composites. / Okabe, Yoji; Yashiro, Shigeki; Tsuji, Ryohei; Mizutani, Tadahito; Takeda, Nobuo.

In: Proceedings of SPIE - The International Society for Optical Engineering, Vol. 4704, 01.01.2002, p. 59-68.

Research output: Contribution to journalConference article

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