Simultaneous determination of curvature, plane of curvature and temperature using a miniaturized sensing head based on fiber Bragg gratings

摘要

We present a novel miniaturized sensor configuration based on fiber Bragg gratings for simultaneous measurement of curvature and temperature. Due to the particular geometry of the sensing head it is possible to measure not only the curvature radius, but also to determine the plane of curvature. This is achieved by arranging three Bragg gratings in the vertices of the smallest equilateral triangle that can be defined by the cross sections of the fibers. The set is then inserted in a glue-filled capillary stainless-steel tube to provide both a suitable protection for the Bragg sensors and rotational symmetry to the sensing head. This tube also ensures isolation from axial-strain, allowing the additional determination of temperature. The proposed sensing head is particularly well suited for applications in smart structures because it can be embedded along any layer of a composite material (including the neutral line) without special concerns on the relative orientation of the Bragg gratings arrangement and the composite layers. This sensing configuration may also be used to implement more sophisticated sensors dedicated to the measurement of multi-axial acceleration or flow and temperature.