The effect of partial slip on wear rate has been studied with the Dynarat program developed at the University of Sheffield. The simulations on a dry rail, with 500MPa mean initial yield stress (with 5% variation) and a smooth surface, have been performed for 80.000 to 175.000 cycles for different values of peak contact pressure (1.5GPa, 1.612GPa, 1.75GPa, 2.172GPa and 3.0GPa). The mean critical shear strain to failure y(c)= 11.5 (with 5% variation). There was work hardening with rate alpha=1, and two values for the hardening ratio beta=1.5, 2. The coefficient of friction was assumed to be constant for the duration of each simulation, and thermal effects were neglected. The results of the simulations show that as the traction coefficients increase, the wear rate increases. Wear rate is significantly influenced by existence of partial slip on the surface when the coefficient of friction is high. If the friction coefficient between the two contacting surfaces is below 0.4 the wear rates for partial slip are not very different from those for complete slip. lncreasing the creepage increases the wear rate, up to a maximum value. In the case of friction coefficient micron = 0.5, the wear rate gets to the maximum value (0.7 micron/cycle) when the creepage reaches about 1.29%. In the case of friction coefficient = 0.6, the wear rate reaches 1.0 micron/cycle when the creepage is about 1.55%. In the case of friction coefficient micron = 0.7, the wear rate becomes 1 .25micron/cycle when the creepage reaches 1.8%. And for friction coefficient micron=0.8, the wear rate attains a maximum value 1.53 micron/cycle when the creepage reaches about 2.06%. The wear rate does not change much for friction coefficients less than 0.7 if the creepage is below 0.5%. This is because neither subsurface nor surface bricks are much affected by small partial slip on the surface. When the wear rate is very low (e.g., for p(0) = 1612MPa, delta (y)=500MPa, beta=1.5, 2) and the traction coefficient is fixed, increasing the coefficient of friction increases the wear rate significantly. For t= 0.199 the wear rate increased from 0.03nm/cycle to 12.7nm/cycle as micron increased from 0.4 to 0.8, and for t = 0.3 the wear rate increased from 0.67nm/cycle to 68nm/cycle. The above wear rates are comparable with the results from the full-scale tests. The wear for the high rail gauge corner after 16 months of traffic (8.1 Mt) was approximately 0.48mm. For the same duration (about 376000 cycles) and similar operating conditions, the total wear predicted by the computer simulation for p(0)=1.55GPa is approximately 0.53mm (i.e., an average wear rate of 1 .42nm/cycle).
The effect of partial slip on the wear rate of rails
2003
8 Seiten, 8 Bilder, 3 Tabellen, 15 Quellen
Conference paper
English
The effect of partial slip on the wear rate of rails
British Library Conference Proceedings | 2003
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