Calibration of FBG strain transducers for superconductors testing
In this paper,a calibration method for FBG strain sensors at different temperatures applicable to conductor testing needs was proposed.The FBG strain sensor was tightly pasted into the V-groove opened by the rod-shaped tensile specimen u-sing low-temperature glue cured under pressure,and the experimental study of step loading calibration was carried out by using a tensile testing machine,and the strain sensitivity coefficients of the FBG strain sensors derived from the calibration were fitted by the centre wavelength and the strain.The strain sensitivity coefficients at room temperature,liquid nitrogen,and liquid helium were measured to be about 1.199 8,1.203 1,and 1.120 4,respectively.It is found that the wavelength offset of the FBG strain sensors shows a linear relationship with the strain at a fixed temperature,and the strain sensitivity coefficients at the temperature of liquid helium are smaller than those at the temperatures of room temperature and liquid nitrogen.
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