## 5 Experimental Validation
### Results and Analysis  
Figure 14 is the temperature distribution diagram of the bearing obtained with a FLUKE TI450 under various working conditions. The results show that the temperature at the inner ring raceway is the highest, and that the lowest temperature appears in the cage. The experimental results and the theoretical simulation diagram yield the same temperature distribution characteristic. Therefore, the next research will focus on the temperature distribution in the inner ring raceway. Figure 12: Overview of the test rig. Figure 13: Structure of the testing system. Figure 15 shows three-dimensional (3D) surface images of the bearing ring, which were obtained with a NewView(tm) 8000 3D optical surface profiler (Zygo inc., Middlefield, CT, USA). Figure 14 shows that the temperature at the inner ring increased from 43.0 \({}^{\circ}\)C to 55.0 \({}^{\circ}\)C in the situations (a) to (c). Figure 15 shows that the surface roughness (Ra) of the bearing inner ring increased from 0.160 \(\upmu\)m to 0.285 \(\upmu\)m and the irregular distribution of the inner ring surface profile was also exacerbated from situations (a) to (c). A more detailed analysis is shown Figures 16 and 17. The preliminary results show that there must be a direct relationship between the temperature distribution and surface topography in the rolling bearing. Figure 14: Temperature distribution diagram of the bearing: (**a**) radial load: 400 N; inner ring speed: 1200 r/min; kinematic viscosity: 15 cSt; (**b**) radial load: 400 N; inner ring speed: 1800 r/min; kinematic viscosity: 15 cSt; (**c**) radial load: 600 N; inner ring speed: 1800 r/min; kinematic viscosity: 32 cSt; and (**d**) radial load: 600 N; inner ring speed: 1200 r/min; kinematic viscosity: 46 cSt. Figure 16: Comparison between the tested and FEM simulation values of temperature under different radial loads (inner ring speed: 1800 r/min, kinematic viscosity: 15 cSt). Figure 15: Three-dimensional (3D) surface images of the bearing inner ring: (**a**) radial load: 400 N; inner ring speed: 1200 r/min; kinematic viscosity: 15 cSt; (**b**) radial load: 400 N; inner ring speed: 1800 r/min; kinematic viscosity: 15 cSt; (**c**) radial load: 600 N; inner ring speed: 1800 r/min; kinematic viscosity: 32 cSt; and (**d**) radial load: 600 N; inner ring speed: 1200 r/min; kinematic viscosity: 46 cSt. (1) The thermal characteristics analysis model of HSLLRBs considering skidding was built, and then the effect of the slip ratio, inner ring speed, and kinematic viscosity on the friction power loss distribution of the bearing were studied. The results show that, as the slip ratio increases, the friction power loss of the inner and outer raceways as well as the total friction power loss of the bearing increase, whereas the friction power loss of the guide surface of the cage and the oil churning of the roller decrease. With the increase in the inner ring speed and the kinematic viscosity, the total friction power loss of the bearing increases. (2) Based on the finite element method, the steady and transient temperature field distributions of HSLLRBs were obtained. The results show that, in the steady-state thermal analysis, the inner ring raceway of the bearing has the highest temperature, and the cage has the lowest temperature. With the increase in slip ratio, the temperatures of the inner and outer ring raceways increase, whereas the cage temperature exhibits a decreasing trend. The transient thermal analysis shows that the temperature of the rolling bearings increases rapidly at first, and thereafter the increase slows down. After a certain time, the bearing reaches the steady-state temperature distribution. (3) The temperature distribution characteristics test rig of the full-size roller bearing was constructed, and the temperature distribution mechanism with a different inner ring speed, radial load, and lubricating oil viscosity was obtained.