Fig. 1. Structure of FBG tension sensor

Fig. 2. FBG tensile sensing performance test device in a wide temperature range

Fig. 3. Temperature response curves of sensor without tensile force. (a) Niobium-based alloy material; (b) austenitic stainless steel material

Fig. 4. Response curves of sensor with tensile force at room temperature. (a) Niobium-based alloy material; (b) austenitic stainless steel material

Fig. 5. Response curves of FBG wavelength shift with tensile force at a set temperature of 250 ℃. (a) Niobium-based alloy material (thermometer 237.9--238.3 ℃); (b) austenitic stainless steel material (thermometer 242.1--242.5 ℃)

Fig. 6. Tensile force response curves of sensor at different temperatures. (a) Niobium-based alloy material; (b) austenitic stainless steel material

Fig. 7. Strain sensing performance parameter change curves of two materials at different temperatures. (a) Repeatability; (b) hysteresis; (c) sensitivity; (d) linearity