PSI - Issue 19

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

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

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1.5

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Critical defect size (mm)

32

34

36

38

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Wheel size (inch)

Fig. 15. Critical defect size with different wheel size.

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Critical defect size (mm)

Before During

After

Tread braking

Fig. 16. Critical defect size with tread braking.

5. Conclusion To assess the effect of the wheel size and tread braking on subsurface crack initiations, the finite element analyses are performed by using different wheel size models and by applying the thermal loading corresponding to the stop braking. The critical defect sizes for subsurface crack initiations are estimated from calculated stress variations at the subsurface for each analysis condition. The equivalent shear stress   eq,max at the subsurface of the 33 – inch wheel is smaller than that of 36 and 38 – inch wheels because the 33 – inch wheel has a smaller wheel load than the other wheels. As a result, the 33 – inch wheel has a larger critical defect size than the 38 and 36 – inch wheels. This indicates that subsurface cracks are less likely to initiate in the 33-inch wheel compared with other wheels. In addition, the critical defect sizes of 38 and 36 inch wheels are almost equivalent in service conditions in accordance with the AAR standard. The critical defect sizes during stop braking or after cooling are larger than that before braking because   eq,max during stop braking or after cooling are smaller than that before braking. This suggests that the tread braking in this study has no negative effect on the subsurface crack initiations. References

[1] S.M. Cummings and D. Lauro, INSPECTIONS OF TREAD DAMAGED WHEELSETS, Proceedings of 2008 ASME Rail Transportation Division Fall Technical Conference, 2008.