# Experimental Research on the Load Transfer Mechanism of Tie Plates for 400 km/h High-Speed Turnouts
## 3 Discussion and Conclusions  
### Discussion of Experiment Results  
The experiment results in Section 2.2.1 are shown in Figure 8. Experimental conditions 1 and 2 have similar curve characteristics: the curve is a nearly linear, flat curve before the cover plate makes contact with the steel sleeve, and the curve changes to a nonlinear, abrupt curve once the cover plate makes contact with the steel sleeve. Under Experimental conditions 1, before the cover plate comes in contact with the steel sleeve, the rubber was mainly compressed with a stiffness of about 0.52 kN/mm. The cover plate came into contact with the steel sleeve when the washer was compressed to about 5.91 mm. Under Experimental conditions 2, before the cover plate came into contact with the steel sleeve, the rubber boss of the tie plate was mainly compressed; for a stiffness of about 0.39 kN/mm, the cover plate came into contact with the steel sleeve when the rubber boss was compressed to about 0.42 mm. Thus, it can be seen that the rubber washer and rubber boss have small stiffnesses, but the stiffness of the rubber washer is higher than that of the rubber boss. Figure 7: Elastic iron tie plate precompression test under Experimental conditions (**a**) 5 and (**b**) 6. The experiment results in Section 2.2.2 are shown in Figure 9. In Experimental conditions 3, the rubber washer was compressed completely when the cover plate displacement was about 6 mm; beyond this point, the tie plate was compressed. In Experimental conditions 4, the rubber boss was compressed completely when the cover plate displacement was about 2 mm, and beyond this point, the tie plate was compressed. Figure 8: Load–displacement curve. Figure 9: Comparison of stiffness curves. A comparison of the tie-plate displacement curves shows that the stiffness of the new tie-plate structure is lower than that of the original tie-plate structure. It can be inferred that in the assembled state, the bolt preload force transferred to the tie plate through the rubber boss in the new structure may be smaller than the bolt preload force transferred to the tie plate through the rubber washer in the original tie-plate structure. The experiment results in Section 2.2.3 are shown in Figure 10, which indicate that with a continuous increase in the bolt preload force, the vertical compression on the new tie-plate structure was always smaller than that on the original tie-plate structure. Under the rated preload force of 100 kN, the vertical compression on the new tie-plate structure was 0.65 mm and that on the original tie-plate structure was 0.82 mm. From the time that the cover plate came into contact with the steel sleeve to the time when the rated torque was reached, the cover plate displacement can be decomposed into two parts: the rubber washer/rubber boss compression deformation before the contact was made, and the subsequent steel sleeve deflection. The displacements of the original and the new tie-plate structures under the rated torque are listed in Table 1.  
A comparison of the two tie-plate structures under the condition of the rated bolt preload shows that the deflection of the steel sleeve of the new tie-plate structure is higher than that of the original structure by 0.83 mm, while the compression of the new tie plate is less than that of the original by 0.17 mm. From the results of Experiment 2, the bolt preload force transferred through the rubber washer is calculated as 15.12 kN when the original tie plate is compressed by 0.82 mm and that transferred through the rubber boss is 9.94 kN when the new tie plate is compressed by 0.65 mm. Therefore, in field assembly, the bolt preload force in the new tie-plate structure is further transferred downward through the steel sleeve, and the force transmitted by the steel sleeve is increased by 5.18 kN.