High Strain Monitoring during Fatigue Loading of Thermoplastic Composites Using Imbedded Draw Tower Fibre Bragg Grating Sensors

Abstract:

This paper presents the experimental study of fibre Bragg grating sensors for measuring strain inside composite laminates during fatigue loading. The optical fibres are imbedded inside thermoplastic CFRP test-coupons which have an ultimate strain of about 1.1%. Tension – tension fatigue cycling at a rate of 5Hz is been carried out at 314MPa with a maximum strain of 0.51%. At such extreme strain levels the use of high strength sensors becomes inevitable. Neither the sensor nor the composite test-coupons showed any significant degradation even after more than 500000 cycles. Fibre optic Bragg grating sensors are known to be very accurate strain sensors but one should be very careful interpreting their response once they are imbedded inside composite materials. In this study high strength fibre Bragg grating sensors with coating are imbedded in composite test coupons and a pretty good correlation was found between the strain measurements of an electrical extensometer and the imbedded sensor during the complete cycling. The high strength sensor show to be very feasible for extreme and long term strain measurements.

• Periodical: Advances in Science and Technology (Volume 56)
• Pages: 441-446
• DOI: https://doi.org/10.4028/www.scientific.net/AST.56.441
• Online since: September 2008
• Authors: Eli Voet, Geert Luyckx, Ives De Baere, Joris Degrieck, J. Vlekken, E. Jacobs, Hartmut Bartelt
• Keywords: Fatigue Cycling, Fiber Bragg Grating (FBG), Fibre Reinforced Thermoplastic Composite, Imbedding, Structural Health Monitoring (SHM)

References

This article has no references.