Evaluation of embedded optical fiber sensors in composites: EFPI sensor fabrication and quasi-static evaluation

This article reports on the fabrication and evaluation of extrinsic Fabry-Perot interferometric (EFPI) sensors when embedded in fiber-reinforced composites and tested under quasi-static tensile and compressive mechanical loading. The EFPI strain sensors were embedded in carbon fiber composite test specimens, and their performance was compared against a surface-mounted extensometer and electrical resistance strain gauges. When the composite was subjected to quasi-static tensile loading, the sensors failed around a strain level of 0.5%; under compressive loading, the sensors survived until the failure of the composite at 1.1% strain. The EFPI sensors used in this study were fabricated in-house and the issues relating to fabrication are discussed in the context of their performance when embedded in composites.