Fig. 1. Structure diagram of OFDR system and optical fiber layout scheme

Fig. 2. Wind turbine blade fluid domain model and its meshing

Fig. 3. Strain distribution of the blade at different moments

Fig. 4. Strain at the leaf root sensing location at different wind speeds. (a) Time domain diagram; (b) frequency domain diagram

Fig. 5. Blade strain distribution at different wind speeds

Fig. 6. Strain distribution per unit cross-sectional area

Fig. 7. Blade strain values at different wind speeds in forward wind. (a) Normalized strain distribution of undamaged blade; (b) normalized strain distribution of damaged blade

Fig. 8. Blade strain values at different wind speeds in reverse wind. (a) Undamaged blade strain distribution; (b) damaged blade normalized strain distribution

Fig. 9. Two-dimensional strain distribution of the blade. (a) Single damage; (b) multiple damages

Fig. 10. Strain with 10% damage degree at 2.4 m of the blade. (a) Normalized strain distribution; (b) normalized strain change rate distribution

Fig. 11. Strain distribution and damage coefficient of the damaged blade. (a) Normalized strain distribution diagram of fan blades with different damage degrees at 1.0 m damage; (b) relationship between damage level and damage factor for different damage cases

Fig. 12. Structure diagram of optical fiber sensing system based on OFDR

Fig. 13. Fiber optic paste method and paste after the specimen

Fig. 14. Strain of cantilever beams. (a) Strain distribution of damaged and undamaged cantilever beams; (b) strain distribution of damaged cantilever beams at different deformations