Issue 52

J. Akbari et alii, Frattura ed Integrità Strutturale, 52 (2020) 269-280; DOI: 10.3221/IGF-ESIS.52.21 274 Fig. 2 illustrates the damage detection results corresponding to the scenarios No. 1. In Figs. a and c the signal energy method has been successfully identified with the damaged elements with clear knobs. This method can identify the multiple damaged elements with a distance of the elements equal to 15cm. However, as can be seen from graphs b and d, the wavelet transform did not succeed in the detection of the damages with a low intensity equal to 5%. Figure 2: Damage detection using signal energy (a,c) and wavelet (b,d) for scenarios 1,2. According to graphs b,d in Fig. 2, in the wavelet method, the disorders (irregularities) in two ends of the support of the beams are observed. Therefore this dilemma makes damage detection a difficult task. In order to overcome this problem, the mode shape has been extended from both ends of the beams. For this purpose, from each side of the supports, 50 elements have been artificially added to the finite - element model, and the results are depicted in Fig. 3. Figure 3: Damage detection using wavelet for scenario no.3. Damages in elements 1 and 100 (a), and Damages in elements 5 and 95 (b).