Intercomparison of Optical FBG-based Strain Sensors and Resistive Strain Gages

摘要

Intercomparison experiments with electrical strain gages and optical fibre Bragg strain sensors were performed in both, tensile strain and bending configurations for 14 FBG sensors at room temperature. The FBG sensors without coating were attached to several metal test species (aluminium, steel, stainless steel) employing a specifically developed gluing procedure. In a total of 53 stepwise load tests, the strain sensitivity of the FBG sensors was found to be reproducible in the order of 0.5%. No significant differences were observed when the FBG sensors were used in tensile strain or in bending mode or when the FBG's were attached to different test materials. Taken the electrical strain gages as reference sensors, the measured strain sensitivities of 14 FBG sensors gave a mean value of k = 0.792±0.016. The accuracy of the measurements is limited by the accuracy of the standard-type electrical strain gages used. The experiments revealed that, if the gluing process is done correctly and if temperature changes are excluded or compensated, the attainable accuracy of FBG strain sensors is at least comparable to that of their electrical counterparts.