PSI - Issue 65

M.A. Skotnikova et al. / Procedia Structural Integrity 65 (2024) 248–254 M.A. Skotnikova, A.Y. Ryabikin, A.D. Shestakov, L.D. Tuptei, A.D. Novokshenov / Structural Integrity Procedia 00 (2024) 000–000 5

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Smoothing was performed using the Hanna method, with a "smoothing window" width of 16 points. Next, the amplitude-frequency characteristics of the friction moment oscillations were calculated (Fig. 4, a, c, e). The Fourier transform is a function that describes the amplitude and phase of each sine wave corresponding to a certain frequency and allows you to decompose the original signal into harmonic components to separate the noise, Ilyichev (2021), Firsova (2014), Harris (1978), Yakimov (2016), Pogorelov (2019), Yurik (2021), Shlyakhtenko (2013), Kamiel (2020), Sahoo (2018). а b

c

d

e

f

Fig. 4. Amplitude-frequency characteristics: a) 09G2S; b) Quard 450; c) Hardox 450 and Frequency Spectrograms: a) 09G2S; b) Quard 450; c) Hardox 450.

As can be seen from Fig. 4 (a, c, e), the decrease in the amplitude of the sine wave of the first (main) harmonic occurred in the direction of 3.40 → 2.15 → 1.40 in steels 09G2S → Hardox 450 → Quard 450, respectively. In the same steels, the second harmonic was formed with sinusoid amplitudes in the direction of 1.50 → 1.60 → (0.85 and 0.70). Unlike the 09G2S and Hardox 450 steels, in the Quard 450 steel with maximum wear resistance, the second harmonic was split into two with amplitudes of 0.85 and 0.70. Thus, the spectra of two exciting forces (abrasive wear and structural-phase (martensitic) transformation) were found in Quard 450 steel, strengthening the surface in the contact zone and increasing its wear resistance. For greater clarity, frequency spectrograms for the studied steels were constructed for 3 studied steels (Fig. 4, b, d, f). Depending on the magnitude of the amplitude at a certain frequency at a certain point in time, the color of the spectrogram changes from dark blue for minimum amplitude values to red at frequencies where this value is maximum.