A novel extrinsic Fabry-Perot interferometric sensor for Inconel 718 tensile properties measurement

This paper reports on the design and implementation of an innovative fiber optic sensor based on extrinsic Fabry-Perot interferometer (EFPI) to accurately measure the tensile strain of the Inconel 718 specimen. The measurement results were compared with the strain measured simultaneously by the electronic extensometer. The fast Fourier transform (FFT) method was used to obtain the cavity length from the real-time spectrum. The proposed EFPI sensor revealed a sensitivity of 26.59 nm/με and a strain measurement range of 166,000 με. By matching strain with the stress measured by tensile testing machine, the full stress-strain curves of the Inconel 718 specimen were obtained at different strain rates from 0.00001/s to 0.001/s. The finite element method (FEM) was used to verify the accuracy of the proposed EFPI sensor.