Issue 58

R. Capozucca et alii, Frattura ed Integrità Strutturale, 58 (2021) 386-401; DOI: 10.3221/IGF-ESIS.58.28

For beam B0, Tab. 5 contains the natural frequencies obtained for each position of the accelerometer at different level of damage. Fig. 4 shows the variations of the experimental frequencies with reference to the damage-free state (D0) for cracking due to the increase in bending; the variation of the experimental frequencies with respect to D0, for all damage levels, for the first four vibration modes, is expressed as:





f

f

f

r

0 D Di



(1)

100

f

f

D

D

0

0

where Di f is the frequency obtained for the damage condition Di and

0 D f is the frequency obtained in the undamaged

condition D0. For beam B1, Tab. 6 summarized the natural frequencies obtained for each position of the accelerometer at different level of damage. The variations of the experimental frequencies with reference to the damage-free state (D0) for cracking due to the increase in bending are shown in Fig. 5.

D0-D1 D0-D2 D0-D3 D0-D4

0 3 5 1 1 1 8 0 3 1 2 2 5 8 0 2 2 3 3 5 8 3 3 0 3 5

Δ f/f D0 [%]

1

2

3

4

Mode

Figure 4: Variation percent of frequencies for beam B0 at different damage degree. D0-D1 D0-D2 D0-D3 D0-D4 D0-D5 D0-D6

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

Δ f/f D0 [%]

1

2

3

4

Mode

Figure 5: Variation percent of frequencies values for beam B1 at different damage degree.

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