Development Of FBG Strain Sensor Calibration System Based On Equal Strength Beam

In this paper,based on equal-strength beams,a static and dynamic calibration test system was developed for FBG strain sensors.The system includes a hardware calibration system and a software calibration system developed by Lab VIEW.The static calibration system can achieve static calibration of(-2000?+2000)??,the repeatability is less than 1.4%,and the standard uncertainty of 13.58×10-6 ?(K=2);The dynamic calibration system can realize dynamic calibration among 3-500 Hz,the calibration strain range is 0?862.48 ??,the relative error is less than 2.04%,and the standard uncertainty is 18.34×10-6 ?(K=2).The principle,advantages and application fields of FBG strain sensor are introduced.The research status of FBG strain sensor in static calibration and dynamic calibration is summarized.Based on the equal-strength beam device,the research target and content of the FBG strain sensor calibration system were proposed in this paper.The principle and application of equal-strength beams are expounded and the dimensions of equal-strength beams are designed by indicator requirements.Through the theoretical calculation and simulation analysis,the feasibility of the designed equal-strength beam was demonstrated.Combined with the characteristics of equal strain that the strain on the surface of equal-strength beams are the same,the static calibration scheme and dynamic calibration scheme of FBG strain sensors were determined.According to the requirements of the dynamic calibration scheme,the laser vibrometer of the test calibration equipment was designed and manufactured,and the accuracy and feasibility of the laser vibrometer were verified by theoretical calculation.The frequency range of the developed laser vibrometer is 0-1000 Hz,the relative uncertainty is 0.5%(K=2),and the relative deviation of the measured displacement is less than 1.4%.The FBG strain sensor calibration system was developed by the PC software Lab VIEW,which can calculate related parameters of calibration and draw the chart conveniently.It can calculate characteristic parameters that include static calibrated sensitivity and linearity and so on;It can fit the sensitivity curve of static calibration;It can relalize the calculated sensitivity andthe fitting sensitivity curve of dynamic calibration.After numerous experiments,it is confirmed that the calibration system can achieve a static calibration with±2000 ?? for FBG strain sensor.The repeatability is less than 1.18%and the accuracy of the static calibration is high.The dynamic calibration range of FBG strain sensor is 3-500 Hz.The maximum calibrated dynamic strain is 862.48 ??.The dynamic calibration system has a relative error less than 2.04%and repeatability less than 1.5%.The FBG strain sensor calibrated test system in this paper has high system stability,good repeatability and low uncertainty.The research of the paper also verifies that the FBG strain sensor has good dynamic characteristics.