Behaviour of intrinsic polymer optical fibre sensor for large-strain applications

Abstract

This paper derives the phase response of a single-mode polymer optical fibre for large-strain applications. The role of the finite deformation of the optical fibre and nonlinear strain optic effects are derived using a second order strain assumption and shown to be important at strain magnitudes as small as 1%. In addition, the role of the core radius change on the propagation constant is derived, but it is shown to be negligible as compared to the previous effects. It is shown that four mechanical and six opto-mechanical parameters must be calibrated to apply the sensor under arbitrary axial and transverse loading. The mechanical nonlinearity of a typical single-mode polymer optical fibre is experimentally measured in axial tension and is shown to be more significant than that of their silica counterpart. The mechanical parameters of the single-mode polymer optical fibre are also measured for a variety of strain rates, from which it is demonstrated that the strain rate has a strong influence on yield stress and strain. The calibrated constants themselves are less affected by strain rate.

Sensing Applications for Plastic Optical Fibres in Civil Engineering

“…This may be supported by the fact that at those levels of strain observed in the study, the loss of intensity in each case did not show evidence of a plateau. In addition, studies conducted by other workers up to 45% [6,7] can be expected while other studies have shown that POF could endure stretching of more than 80% strain under certain conditions [10].…”

“…Compared to GOFs of the same diameter, POFs are lighter, cheaper and less prone to flexural damage. In addition, POF has an elastic limit of an order higher than GOF [6,7] and it has been shown that standard step-index PMMA POF can be integrated into geotextile materials to measure strains up to 40%. When it is desirable to embed sensors within concrete structures, POF sensors offer a possible solution since the extremely alkaline (pH 12) environment of the concrete mixture is known to be corrosive to standard glass fibres [8].…”

Compensation of Ultrasound Attenuation in Photoacoustic Imaging

“…Furthermore the Young's modulus is much lower in polymer fibers than in glass fibers for which reason the deformation of a polymer fiber is bigger than of a glass fiber applying the same pressure wave. As the strain optic coefficients are in the same order, this results in an enhanced change of refractive index and thus to higher signal amplitudes in the polymer fiber (Kiesel et al, 2007). (Nuster et al, 2009) did a comparison of the different implementations of an integrating line detector.…”

Measurements of polarimetric sensitivity to hydrostatic pressure, strain and temperature in birefringent dual-core microstructured polymer fiber

“…In particular, POF is biocompatible, offers greater numerical aperture, more flexibility (lower Young's modulus) and can be exposed to much greater strain compared to silica. For these reasons, conventional POF has been already studied in numerous sensing applications including measurements of large strains [7][8][9], humidity [10], and pH [11]. The inscription of Bragg gratings in POF, first demonstrated in [12], opens now new sensing possibilities [13,14].…”