PSI - Issue 54

J.V. Araújo dos Santos et al. / Procedia Structural Integrity 54 (2024) 575–584

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Author name / Structural Integrity Procedia 00 (2019) 000 – 000

Case 1

Case 5

(a)

Case 1

Case 5

(b) Figure 4.2: Identification of damage scenario 1 with the norm of modal strains computed by differentiation filters with 11 points and 3rd degree polynomials: (a) 3rd mode, (b) 9th mode 4.3. Selection of Savitzky-Golay Filter The damage identifications presented in this and the following section were obtained by computing the third mode strains and their norm. Figures 4.3 and 4.4 show several damage identifications obtained by applying differentiation filters with 3rd-degree polynomials ( = =3 ) and (a) 5 points ( = =2 ), (b) 11 points ( = =5 ), (c) 21 points ( = =10 ). The results with 5 and 11 points do not seem very different, but the identifications with 21 points present some distortions, originating a slight decrease in the peak values. The results obtained by differentiation filters with 3rd, 5th, and 7th degree polynomials show that this parameter does not influence much the quality of the damage identifications. As can be observed in Figure 4.5, which presents identifications with 11 points filters, the differences are almost unnoticeable.

(a) (c) Figure 4.3: Identification of damage scenario 1, case 5 with the norm of modal strains computed by differentiation filters with 3rd-degree polynomials and: (a) 5 points, (b) 11 points, (c) 21 points (b)

(a) (c) Figure 4.4 : Identification of damage scenario 3, case 5 with the norm of modal strains computed by differentiation filters with 3rd-degree polynomials and: (a) 5 points, (b) 11 points, (c) 21 points (b)

(a) (c) Figure 4.5 : Identification of damage scenario 1, case 5 with the norm of modal strains computed by differentiation filters with 11 points and: (a) 3rd degree, (b) 5th degree, (c) 7th degree polynomials (b)