## 4 Physical Experiment
### Physical Experiment Measurement Results
#### 4.2.2 Sound Measuring Results  
Sound recordings were made using the sound measuring equipment. At the same time, video was recorded and the timestamp taken. The measured parameters include sound power, Pa; sound power level of the sound frequencies, dB; and time of sound recording, Hz. The time is recorded in the sound recording track recorded by the equipment; the \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Wheelset** & **F, kN** & **F, kN** & **F,ref, kN** & **F,ref, kN** & **L,w, dB** & **L,w, dB** \\ \hline
69 & 364.13 & 469.71 & 25 & 33 & 11.6332 & 11.5332 \\
71 & 307.84 & 414.08 & 25 & 33 & 10.796 & 10.9857 \\
85 & 300.29 & 407.38 & 25 & 33 & 10.796 & 10.9149 \\
87 & 323.61 & 427.04 & 25 & 33 & 11.1208 & 11.1195 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Sound power change calculation results are theoretical, at different forces \(F\), \(F_{r}\), \(F_{ref}\) and \(F_{ref}\), and sound force change parameters \(L_{\rm w}\) and \(L_{\rm wr}\). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Wheelset** & **F, kN** & **F, kN** & **F,ref, kN** & **F,w, kN** & **t, s** & **v, m/s** \\ \hline
69 & 364.13 & 469.71 & 183 & 290.66 & 17.738 & 12.86 \\
71 & 307.84 & 414.08 & 183 & 290.66 & 18.467 & 12.81 \\
85 & 300.29 & 407.38 & 183 & 290.66 & 22.142 & 12.62 \\
87 & 323.67 & 427.04 & 183 & 290.66 & 22.945 & 12.59 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: ATLAS LG results. Maximum force, \(F\); reduced ATLAS LG system (hereafter referred to as reduced) maximum force, \(F_{r}\); reference force, \(F_{ref}\); reduced reference force, \(F_{ref}\); time, t; wagon speed, \(v\). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Wheelset** & \multicolumn{2}{c}{**T, s**} & \multicolumn{2}{c}{**f, Hz**} \\ \cline{2-5}  & **If the Wheel Is New** & **If It Is Worn** & **If the Wheel Is New** & **If It Is Worn** \\ \hline
69 & 0.2320 & 0.2298 & 4.3111 & 4.3523 \\
71 & 0.2329 & 0.2307 & 4.2943 & 4.3354 \\
85 & 0.2364 & 0.2341 & 4.2306 & 4.2711 \\
87 & 0.2369 & 0.2347 & 4.2206 & 4.2610 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Periods (T) and frequencies (f) of the damage repetition of the new and worn wheel. changes of the sound pressure in it are entered in such time intervals with the accuracy of 0.001953125 s. Later, the data of the sound recording were compared with ATLAS LG and the data of the video recording. Measurements record changes in sound power in the environment and over time. We assume that everything surrounding what is going on is a sound benchmark, and a change in the forces acting between the wheel and the rail causes a change in sound power. We filter these changes based on the repetition time and period. Comparison of ATLAS LG data, video recordings and sound recordings allowed for determining the possible time of the defect. Data were filtered using the defect repetition period (Table 3) and the time of defect registered by the ATLAS LG system. The results are presented in the Table 5.  
Based on ATLAS LG data, defective wheels were identified. According to the instructions of this equipment, the wheel defect criteria follow:  
Fr > 450 kN--is an impermissible fault, i.e., a damage (a flat spot, or wheel flat) depth exceeding 2 mm and length exceeding 100 mm;  
450 kN > Fr > 350 kN--there is damage (a flat spot or wheel flat) within the normal range, up to 2 mm depth and up to 100 mm length. This system records the detected defect time, the wheel number, the force, the speed and the side of the wheel where the damage is. Therefore, taking into account the ATLAS LG fixed time (column 6 of Table 2), the repetition periods of possible wheelset damage (Table 3) and the recorded start time of the recording of sound pressure changes, the data of Table 5 were obtained.