Fig. 1. Magnetostrictive strain-magnetic field curve of GMM

Fig. 2. Basic principle of double grating-intensity demodulation method. (a) Spectrum of broadband light source; (b) reflection spectrum of sensing FBG and reference FBG; (c) change of reflection spectrum under stress; (d) change of reflection spectrum under combined action of stress and temperature

Fig. 3. Schematic of sensor test system

Fig. 4. Magnetic flux density distribution of system

Fig. 5. Axial flux density distribution curves of sensing GMM and reference GMM

Fig. 6. Relationship among magnetic field distribution of sensing GMM and reference GMM and position of reference GMM. (a) Curve of p values changing with reference GMM position; (b) curves of m values changing with reference GMM position

Fig. 7. Relationship among p, m and length of reserved expansion space

Fig. 8. Relationship between magnetic field distribution of sensing GMM and cross-sectional side length of magnetic ring

Fig. 9. Relationship among p, m, and opening length above magnetic ring

Fig. 10. DC characteristic curves of sensor

Fig. 11. Input/output relation of sensor without bias current

Fig. 12. Amplitude frequency characteristic curve of sensor

Fig. 13. Sinusoidal input-output curves at different frequencies. (a) 50.0 Hz; (b) 2.0 kHz; (c) 4.0 kHz; (d) 6.5 kHz; (e) 8.0 kHz; (f) 10.0 kHz

Fig. 14. Layout diagram of sensor temperature characteristic test system

Fig. 15. Temperature characteristic test curves of sensor. (a) Gain; (b) phase difference