Embedded gold-plated fiber Bragg grating temperature and stress sensors encapsulated in capillary copper tube

Abstract

In order to realize the non-destructive and real-time dynamic stress monitoring method of the construction machinery surface in complex and harsh environments, a fiber Bragg grating (FBG) stress sensor packaging method based on magnetron sputtering technology is proposed. Two packaging methods of complete embedding (the capillary copper tube embedded in the entire grating area) and two sides embedding (capillary copper tube nested at both ends of the grating area) are studied. The sensitization effect of the sensor is analyzed from the perspective of theory and finite element, and the results are consistent. The physical sensors are made, and temperature, stress, and comparison experiments are carried out. Simulation and experiment show that the FBG sensor improves the sensitivity by about 7.5% under this model. The temperature experiment shows that the temperature feedback correlation coefficient R2 of the second package structure reaches 0.99948, which shows good linearity in the range of 30 ℃80 ℃; the stress experiment correlation coefficient R2 also reaches 0.99924, and the sensitivity is 6.14 pm/MPa. The accuracy of demodulation system reaches 0.05 MPa, it can demodulate stress quickly and accurately. Comparative experiments show that the monitoring system composed of grating demodulator has higher accuracy than the monitoring system composed of strain gauges, and maximum deviation value smaller 59.8%. The packaging structure of metallization method of embedded capillary copper tube combined with organic glue fixed is simple, high sensitivity, and precision, can meet the needs of large-scale construction machinery surface non-destructive real-time health monitoring.