Issue 59

M. Seguini et al, Frattura ed Integrità Strutturale, 59 (2022) 18-34; DOI: 10.3221/IGF-ESIS.59.02

Crack depth (mm)

Mode 1 212.03 211.78 211.21 210.66 209.92 209.14 208.23 207.19 206.03 204.76 204.37 202.15 200.48 198.57 195.68 194.04 190.61 185.48 181.51 177.39 172.96 170.16 162.92 150.97 146.81 146.79 146.76 146.74 146.74 146.67 146.61 146.38 146.18 145.85 144.97 144.48 188.3 157.5 146.5

Mode 2 578.68 578.68 578.58 578.69 578.69 578.69 578.68 578.73 578.72 578.71 578.69 578.68 578.66 578.65 578.62 578.61 578.57 578.55 578.51 578.48 578.43 578.39 578.36 578.26 578.19 578.18 578.07 577.87 577.83 577.78 577.55 577.36 576.95 576.71 567.72 538.03 506.77 502.26 578

Mode 3 1117.4 1116.4 1114.1 1109.4 1106.4 1103.0 1099.2 1094.9 1090.2 1088.7 1080.7 1074.8 1068.2 1058.5 1053.1 1042.1 1034.9 1026.4 1014.7 991.02 983.69 965.67 952.94 938.45 924.08 896.31 886.75 882.01 856.86 838.72 832.61 812.76 1112 1003 911.8

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

802.4 794.3

785.45 781.24

Table 8: Experimental frequencies of different crack depths (beam II).

E XPERIMENTAL ANALYSIS

n this section, the healthy and damaged free-free beams have been analyzed by using M+P SO Analyzer 4.3, PCB Accelerometers 356A15, and Hammer PCB 086C03. In the first example, the accelerometer has been put on the left side of the beam (Fig. 12c) to determine the frequencies where 19 excisions have been generated by a Hammer, and ten double notches have been created in the middle of the beam I. On the other hand, in the second beam, the accelerometer is located in the right of this later where five crack depths have created in the middle of the beam, and the frequencies of 3 mode shapes have been calculated after the average of 11 positions of hammer impact. I

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