PSI - Issue 28

Daniel Mella et al. / Procedia Structural Integrity 28 (2020) 511–516

514

4 Mel la D. A. et al. / Structural Integrity Procedia 00 (2020) 000–000 Four unidimensional displacements were imposed in the cylinder free end x c = ([0 . 5 , 1 , 1 . 5 , 2] , 0) D , measuring the reaction moment M p in the fixed end of the stainless steel rod. The ratio M p / x c for all tested x c was 3.88. Thus, the bending stresses associated to a given displacement x c was calculated as

. 88 x c D 2 I

σ = 3

(1)

where I = πD 4 / 64 is the moment of inertia.

4. Results 4.1. Cylinder response

0 . 4 0 . 6 0 . 8 1 1 . 2

0 . 3

0 0 . 2 0 . 4 0 . 6 0 . 8

0 . 2

f y /f nw

A ∗ osc,x

A ∗ osc,y

0 . 1

0

3

4

5

6

3

4

5

6

3

4

5

6

U r

U r

U r

(b)

(a)

(c)

Fig. 2: Maximum response and oscillation frequency of a pivoted cylinder subjected to 2 . 26 ≤ U r ≤ 5 . 87 . a) Maximum streamwise response, error bars: A ∗ osc,x ± SD x . b) Maximum crossflow response, error bars: A ∗ osc,y ± SD y . c) Crossflow oscillation frequency

− 1 − 0 . 5 0 0 . 5 1

y/D

− 0 . 2

0

0 . 2

0 . 4

0 . 6

0 . 8

1

x/D

Fig. 3: Cylinder trajectory at different U r .

: U r = 2 . 67 ,

: U r = 4 . 81 .

: U r = 5 . 89

Figure 3 shows the trajectory traced by the cylinder at different flow velocities. A dominant crescent type trajectory is observed as U r increases. The cylinder response in a given direction was decomposed as the sum of an oscillatory A osc and mean A displacement. As shown in Figure 3, A y ≈ 0 , whereas A x