## 6 Application Cases
### Operating Mechanism of EMU Bogie Wheel Pair System Fault Processing  
The fault-processing operating mechanism of an EMU bogie driven by digital twin is shown in Figure 10. The fault data of the bogie are processed and analyzed via the twin data platform of the digital twin. The bogie wheel pair fault prediction data are conveyed \begin{table}
\begin{tabular}{c c c} \hline
**No** & **Failure Mode** & **Predicted Data** \\ \hline
15 & Te equivalent taper of the tread is too large & 3 \\ \hline
16 & Oil plugging head broken & 2 \\ \hline
17 & Speed sensor resistance is abnormal & 3 \\ \hline
18 & Oil leakage of coupling & 1 \\ \hline
19 & Wear of shaft disc & 1 \\ \hline
20 & Hollow shaft deposits & 3 \\ \hline
21 & Air spring damaged & 1 \\ \hline
22 & Axle box temperature too high & 2 \\ \hline
23 & Brake valve is leaking air & 3 \\ \hline
24 & Oil leakage of gearbox & 3 \\ \hline
25 & Abnormal sound & 7 \\ \hline
26 & Axle crack & 1 \\ \hline
27 & Shock absorber connecting bolt is loose & 2 \\ \hline
28 & Gearbox magnetic bolt failure & 2 \\ \hline
29 & Damage of baffle & 1 \\ \hline
30 & Brake clamp clearance reduced & 2 \\ \hline
31 & Antisnake shock absorber oil leakage & 2 \\ \hline
32 & Damaged positioning node & 3 \\ \hline
33 & Crack in spoke plate & 3 \\ \hline
34 & Sand heating system malfunction & 2 \\ \hline
35 & Lateral acceleration exceeded & 3 \\ \hline
36 & The axis does not rotate & 2 \\ \hline
37 & Shaft height valve air leakage & 2 \\ \hline
38 & A foreign body inside the traction motor & 2 \\ \hline
39 & Disc damage & 2 \\ \hline
40 & Shaft disc damage & 2 \\ \hline
41 & Gearbox magnetic bolt failure & 2 \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._to each unit for fault processing in combination with the actual operation condition of the EMU, repair point, and parts inventory of the manufacturing workshop. The repair data and manufacturing data are fed back to the design department, which will carry out optimization design as per the actual problems. Based on the prediction results, the corresponding fault repair and data feedback are carried out in conjunction with the O&M sites, the wheelset design department, the wheelset inventory, and the axle inventory. In such an operating mechanism, the data platform conveys the processed fault data and some other fusion data to the virtual model layer for virtual simulation. After the virtual layer accepts data such as maintenance time, parts inventory, and maintenance personnel, an initial set of O&M plans can be generated promptly. Then, the optimal O&M plan is sent to the corresponding O&M point for execution and synchronizes simulation at the virtual layer to achieve repair of the EMU wheel pair. The optimal repair plan information is sent to the manufacturing center to verify whether the corresponding vehicle wheel, bearing, gearwheel inventory, etc., meets the current O&M demands. If met, the corresponding part inventory shall be allocated as per the optimal O&M plan for repair at the repair point. If not, the demand information shall be sent to the virtual manufacturing unit and the production plan is promptly formulated for production simulation. The production simulation shall be carried out simultaneously with the actual product; otherwise, the corresponding production plan is promptly adjusted untie consistency is reached. Finally, the finished products shall be sent to the O&M point for repair as required. The best maintenance plan information, production plan, scheduling information, and actual maintenance information generated during the wheel-to-wheel troubleshooting process are stored in the twin data platform. It is updated to a usable knowledge base to provide timely responses to the next occurrence of the problem.