PSI - Issue 80

Francisco J.G. de Oliveira et al. / Procedia Structural Integrity 80 (2026) 1–10 Author name / Structural Integrity Procedia 00 (2023) 000–000

6

6

n − 1 j = 1

2 ∆ L × ε n − 1 l t

(i) ,

β j

β n =

+

(2)

δ n =∆ L ×

+ β n − 1 + δ n − 1 (ii) ,

2 ∆ L × ε n − 1 l t

where β n and δ n denote the local rotation and deflection, respectively, of the instrumented regions. The fibre-optic sensing lines allow the deformation and rotation at each spanwise polar location to be determined, which are then iteratively projected along the cylinder span to reconstruct the overall deflection. Although the sensing domain begins at y / D ≈ 1 . 6, the resulting reconstruction provides a su ffi ciently accurate estimate of the actual deflection to compare the time-averaged loading across di ff erent FST inflows. Figure 4 a) shows the time-averaged strain distribution obtained from the four sensing paths, together with the corresponding reconstructed deflection fields. To quantify the mean structural response, the largest deflection at the tip, averaged across all fibres, is computed as

N f ibres i

1 N f ibres

δ ( t , i , y ≈ 9 D ) .

(3)

δ tip =

This measure is presented in Figure 4 b) and represents the spatio-temporally averaged load transmitted to the can tilever, expressed through its mean deformation.

a)

b)

'

0.60

0.80

0.40

0.20

y/L

α ∈ [45 , − 45 , 135 , − 135] ◦ represented by , , and . b) :

Fig. 4. a) : Time averaged strain ( µε )( ) and deflection ( δ ) ( ) obtained by θ α f , Free-end deflection of the blu ff body for the duration of the conducted tests. Adapted from de Oliveira et al. (2025).

Figure 4 b) shows that increasing turbulence intensity TI (%) leads to larger tip deflections, reflecting a direct am plification of the spatio-temporally averaged loads acting on the cylinder (de Oliveira et al., 2025). This observation is consistent with the findings of Bearman and Morel (1983b) for three-dimensional wake-generating bodies. To further investigate the dynamic response, frequency-weighted power spectral densities (PSDs) of the normalised fluctuating deflection rate were computed from the strain signals acquired along the sensing path θ α f ,α = − 45 ◦ , − 135 ◦ ]. Results for FST cases 1 a and3 a are presented in figures 5 a) and b) , respectively, across several spanwise positions of the cylinder.