Assessing Reliability of cm-Scale Optical Fiber Strain Sensing in High Gradient Configurations through Benchmarking and Mechanical Modelling

FBG-WDM, FBG-FMCW and OFDR distributed strain monitoring techniques are benchmarked and compared to FEM results, in view of assessing the performance of SHM of complex high-value structures subject to intense stress concentration. The results reveal distinct performance trade-offs: OFDR provides the highest accuracy but fails at high gradients (>100 µε/mm), while FBG-based methods are more robust, but their accuracy is algorithm-dependent due to spectral chirp. The CFG-FMCW technique systematically underestimates peak strains due to spatial filtering, confirming that no single technology is universally optimal for highgradient monitoring.