## 3 Multi-Body Dynamics Analysis Model of Disc Brake Coupling in High-Speed Trains
### Finite Element Model of Disc Brake Braking Process
#### 3.2.3 Verification of Finite Element Model  
To ensure the accuracy of the established multi-body dynamics analysis model of the disc brake coupling effect of high-speed trains, this paper adopts a scaled inertial brake test bench (as shown in Figure 5) to test the above model. The initial braking pressure was 0.36 MPa, and the braking condition with the initial speed of 200 km/h was tested. The straight-line distance between the infrared thermal imager and the brake disc surface was 1.5 m, the test environment temperature was 20 \({}^{\circ}\)C, the emissivity was set to 0.85, and the ambient humidity was 31%. The signals of the braking time, friction coefficient, and temperature at the friction radius of the brake disc surface during the braking process were collected through a scaled inertia test bench, and the temperature of the brake disc surface was collected through an infrared thermal imaging camera.  
The results under the assumptions of the initial braking speed of 200 km/h, the initial pressure of 0.36 MPa, and the initial temperature of 20 \({}^{\circ}\)C were derived through the analysis and calculation of the model constructed in Section 3.2.2. Figure 6 illustrates a comparison between the temperature curve during the braking process obtained from the aforementioned scaled inertial braking test and the temperature curve at the surface friction radius (\(R\) = 260 mm) of the high-speed train brake disc.  
In Figure 6, the temperature curve obtained from the simulation and the test both exhibit the same overall change trend, which is a parabolic change. The temperature rose quickly during the initial stages of braking due to the high rotation speed of the brake disc, high dissipation rate of friction of the brake pads to the brake disc, and high heat flow intensity. The temperature curve obtained by simulation reached its maximum value of 226 \({}^{\circ}\)C at 30 s, while the temperature curve obtained by test reached its maximum value of 235 \({}^{\circ}\)C at 34 s. The heat flow intensity decreased, the dissipation rate of friction gradually decreased, and the speed of the brake disc further decreased as the braking process continued. The effects of heat conduction, convective heat transfer, and radiation heat dissipation of the brake disc were greater than those of the frictional heat flow. The test temperature fell to 169 \({}^{\circ}\)C until the end of braking, while the simulated temperature dropped to 190 \({}^{\circ}\)C. Comparing the two curves, the test temperature rise rate was lower than the simulation before 28 s because of the uneven contact between the brake disc and the brake pad. The temperatures of the two gradually tended to be the same, and after 42.5 s as the braking progresses, the test temperature value was marginally lower than the  
Figure 5: Scaled inertia brake test bench.  
simulated temperature value. Considering the influence of the test error comprehensively, the simulation temperature change curve of the brake disc and the temperature change curve of the test brake were both parabolic and shared the same temperature change regulations, so the accuracy of the simulation model was confirmed.