Dual Bragg grating sensor for concurrent torsion and temperature measurement

Abstract

The paper discusses a dual fibre Bragg grating sensor for the independent measurement of temperature and torsion in a rotating shaft. It shows theoretically that torsion affects the differential wavelength of the gratings in the proposed configuration, whereas temperature changes only the common-mode wavelength, allowing measurement of both torsion and temperature. For the particular system investigated experimentally, the differential wavelength change due to torque was 19.4 pm (N m)−1, and the corresponding temperature sensitivity was −0.36 pm °C−1. In contrast to these values, the temperature sensitivity of the common-mode wavelength change was 25.3 pm °C−1, and its torque cross-sensitivity was −0.19 pm (N m)−1.