PSI - Issue 54

V.M.G. Gomes et al. / Procedia Structural Integrity 54 (2024) 561–567 Author name / Structural Integrity Procedia 00 (2023) 000–000

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Fig. 5. Comparison between vertical displacement and surface stress data before and after applying the Butterworth low-pass digital filter.

The value of f cut = 25 Hz because these order of frequencies are observed in rail vehicles. In addition, the value of cut-o ff frequency is confirmed by applying the fast Fourier transform method to the signals presented in Fig. 5. According to Fig. 6 that shows the result of applying the fast Fourier transform to the vertical displacement range signal, ∆ δ v, and to the longitudinal stress range, ∆ σ , cut-o ff frequencies around 15 Hz removes the signal noise.

3.3. Comparison between Standard, Numerical and Experimental Results

The gathered data set in Fig. 5 is compared with the leaf spring structural response model obtained from the numerical model (green curve), the first point collected by the acquisition system (red point), and UIC 517 standard (UIC 517 (2007)) stress-displacement curve (dashed black curve). The red point refers to the time in which the wagon is loaded and therefore it corresponds to a static loading condition without any interference from dynamic movements.

Max δ v = 176 mm

Max Δ σ = 1833 MPa

Fig. 6. Identification of the cut-o ff frequency after applying the applying the the Fast-Fourier Transform to the vertical displacement and stress data.