PSI - Issue 19

T. Kato et al. / Procedia Structural Integrity 19 (2019) 238–248

241

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Author name / Structural Integrity Procedia 00 (2019) 000 – 000

Both tread braking and rolling contact loadings are applied to the wheel-rail model simultaneously. These analyses are conducted continuously after the above analyses. The rolling contact analyses are performed in two situations, when the temperature of the wheel is elevated by tread braking and after cooling of the wheel. The objective of the analyses after cooling is to evaluate the effects of the residual stress caused by tread braking on the subsurface crack initiations. A stop braking is applied in the tread braking analyses, and its time history of braking energy is shown in Figure 5. The stop braking corresponds to a braking condition with an axle load of 350 kN, maximum speed of 113 km/h, and braking time of 92 s. The heat input width at the tread surface is 69 mm, and distribution of the heat flux is uniform. The contact position of the tread center between the wheel models and the rail models is only applied in the tread braking condition. A procedure of tread braking analyses are similar to that of heat treatment analyses, which implies that the distributions of wheel temperature are calculated by the heat transfer analyses, and then, stress distributions of wheel rim are calculated by the thermal stress analyses. A commercial software ABAQUS Ver.6.12 is used for the finite element analyses.

a

b

c

Front rim side

Flange side

Tread center

30 mm

72 mm

50 mm

Fig. 3. Contact positions between the wheel and the rail model; (a) flange side; (b) tread center; (c) front rim side.

Vertical load 122.3 - 175 kN

40 mm rolling

0.5% slip

Fig. 4. Finite element analysis conditions.

Table 1. Applied vertical loadings on each wheel size. Wheel size Vertical loading (kN)

Maximum contact pressure (MPa)

B38 H36

175.0 159.0 122.3

1541 1517 1427

J33