Frequency characteristics of hetero-core fiber accelerometer with two orthogonal vibrational modes of an arch shape beam structure

In this paper, a hetero-core optical fiber accelerometer has been evaluated with respect to temporal and frequency response to dynamic vibration. The proposed accelerometer has a simple arch structure in which a hetero-core fiber sensor was located at the center of the arch supported at both ends of a curved beam. The accelerometer is devised for applications intended for in the defect diagnosis of mechanical structures based on abnormal vibration monitoring, with being capable of rejecting electromagnetic interference, temperature fluctuation, and chemical corrosions. Temporal responses and frequency characteristics were experimentally verified by giving sinusoidal vibration. The waveform of optical loss change in the in-plane mode of the semicircle was found to precisely match the given sinusoidal vibration of 50 Hz. Natural frequencies were found at near 120 - 140, 340 and 760 Hz for the orthogonal two modes for in-plane and out-of-plane. Comparing the sensitivities of the in-plane and out-of-plane modes at frequencies below 100 Hz, the in-plane mode shows more sensitive to be 1.7×10
^-4
dB/g than that of the out-of-plane, 1.9×10
^-5
dB/g.