PSI - Issue 80

Francisco J.G. de Oliveira et al. / Procedia Structural Integrity 80 (2026) 1–10

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Author name / Structural Integrity Procedia 00 (2023) 000–000

Together, the mean and RMS strain datasets demonstrate the potential of distributed fibre-optic sensing for re solving the spatial structure of turbine blade loading. By capturing both average and fluctuating components, this methodology isolates how operating conditions redistribute structural demand along the blade span.

5. Conclusions

We presented a novel fibre optic sensing framework to investigate fluid-structure interactions in both canonical and applied settings. For the cantilevered cylinder, free-stream turbulence (FST) was shown to enhance structural loading primarily through indirect modification of vortex shedding dynamics, increasing spanwise coherence and amplifying fluctuating root stresses. For the wind turbine, tip-speed ratio ( λ ) was the dominant parameter governing the distribution of blade strain: loads peaked at the design operating point, and homogenised across the span at above optimum λ . Time-averaged and RMS strain spanwise evolution demonstrate how blade dynamics are heterogeneous across its span, and highly dependent on the dynamics of the turbine as a function of the operating regime. These results highlight two unifying mechanisms: (i) inflow turbulence modifies structural dynamics primarily via coherent wake structures, and (ii) operating condition dictates the spatial distribution and intensity of the structural response. Together, these findings show the potential of distributed fibre-optic sensing to uncover fatigue-relevant loading pathways in engineering structures, providing valuable datasets for future design and control strategies. Barthelmie, R.J., et al., 2009. Quantifying the impact of wind turbine wakes on power output at o ff shore wind farms. Journal of Atmospheric and Oceanic Technology 26, 1084–1101. Bastankhah, M., Porte´-Agel, F., 2017. A New Miniature Wind Turbine for Wind Tunnel Experiments. Part I: Design and Performance. Energies 10, 908. Bearman, P.W., Morel, T., 1983a. E ff ect of free stream turbulence on the flow around blu ff bodies. Progress in Aerospace Sciences 20, 97–123. Bearman, P.W., Morel, T., 1983b. E ff ect of free stream turbulence on the flow around blu ff bodies. Progress in Aerospace Science 20, 97–123. Chamorro, L., Porte´-Agel, F., 2011. A wind-tunnel investigation of wind-turbine wakes: boundary-layer turbulence e ff ects. Boundary-Layer Meteorology 132, 129–149. Kankanwadi, K., Buxton, O.R.H., 2023. Influence of freestream turbulence on the near-field growth of a turbulent cylinder wake: Turbulent entrainment and wake meandering. Physical Review Fluids 8, 034603. Li, Y., Sharif-Khodaei, Z., 2025. Shape sensing of composite shell using distributed fibre optic sensing. International Journal of Mechanical Sciences 286, 109859. Maryami, R., Aki, S.A.S., Azarpeyvand, M., Afshari, A., 2020. Turbulent flow intereaction with a circular cylinder. Physics of Fluids 32, 015105. de Oliveira, F.J.G., Sharif-Khodaei, Z., Buxton, O.R.H., 2024. Simultaneous measurement of distributed strain and velocity for a cantilevered cylinder in cross-flow. Experiments in Fluids 65. de Oliveira, F.J.G., Sharif-Khodaei, Z., Buxton, O.R.H., 2025. The influence of free-stream turbulence on the fluctuating loads experienced by a cylinder exposed to a turbulent cross-flow. Journal of Fluid Mechanics 1011. Pan, Y., Sharif Khodaei, Z., Aliabadi, M.H., 2025. In-service fatigue crack monitoring through baseline-free automated detection and physics informed neural network quantification. NDT & E International 153. Porteous, R., Moreau, D.J., Doolan, C.J., 2014. A review of flow-induced noise from finite wall-mounted cylinders. Journal of Fluids and Structures 51, 240–254. Rind, E., Castro, I.P., 2012. On the e ff ects of free-stream turbulence on axisymmetric disc wakes. Experiments in Fluids 53, 301–318. Stevens, R., Meneveau, C., 2017. Flow structure and turbulence in wind farms. Annual Review of Fluid Mechanics 49, 311–339. Thomsen, K., Sørensen, P., 1999. Fatigue loads for wind turbines operating in wakes. Journal of Wind Engineering and Industrial Aerodynamics 80, 121–136. Veers, P., Dykes, K., Lantz, E., Miner, S., Bir, G., et al., 2019. Grand challenges in the science of wind energy. Science 366, eaau2027. Wang, P., et al., 2019. Turbulent intensity e ff ect on axial-flow-induced cylinder vibration in the presence of a neighboring cylinder. Journal of Fluids and Structures 85, 77–93. Williamson, C.H.K., 1996. Vortex dynamics in the cylinder wake. Annual Review of Fluid Mechanics 28, 477–539. Xu, T., Sharif-Khodaei, Z., 2020. Distributed strain sensing of composite structures using rayleigh backscattering. Measurement Science and Technology 31, 075107. Zhou, Y., Mi, J., Bearman, P.W., Brøns, M.J., 1999. On fibre optic strain sensing of flow-induced loads. Journal of Fluids and Structures 13, 151–166. References