We have systematically measured the differential stress-optic coefficient, ΔC, and Young's modulus, E, in a number of
PMMA fibers drawn with different stress, ranging from 2 up to 27 MPa. Effect of temperature annealing on those
parameters was also investigated. ΔC was determined in transverse illumination by measuring the dependence of
birefringence on additional axial stress applied to the fiber. Our results show that ΔC in PMMA fibers has a negative sign
and ranges from -4.5 to -1.5×10-12 Pa-1 depending on the drawing stress. Increase of the drawing stress results in greater
initial fiber birefringence and lower ΔC. The dependence of ΔC and initial birefringence upon drawing stress is nonlinear
and gradually saturates for higher drawing stress. Moreover, we find that ΔC is linearly proportional to initial fiber
birefringence and that annealing the fiber has no impact on the slope of this dependence. On the other hand, no clear
dependence was observed between the fiber drawing stress and the Young's modulus of the fibers as measured using
microscopic digital image correlation with the fibers tensioned using an Instron tension tester.
Fibre Bragg gratings (FBGs) in polymer optical fibres (POFs) have been used to measure the strain in a woven textile.
FBGs in both POFs and silica optical fibres were attached to a woven textile specimen, and their performance
characterised. It was demonstrated that the POF FBGs provide improved strain transfer coefficients and reduce local
structural reinforcement compared to silica FBGs and therefore make a more suitable proposition for textile monitoring.