A. Bhaskar et al., WHEEL-RAIL DYNAMICS WITH CLOSELY CONFORMAL CONTACT .2. FORCED RESPONSE, RESULTS AND CONCLUSIONS, Proceedings of the Institution of Mechanical Engineers. Part F, Journal of rail and rapid transit, 211(1), 1997, pp. 27-40
The linearized dynamic models for the conformal contact of a wheel and
rail presented in reference (1) have been used to calculate the dynam
ic response to a prescribed sinusoidal ripple on the railhead. Three m
odels have been developed: single-point contact with low or high confo
rmity, and two-point contact. The input comprises a normal displacemen
t Delta e(i omega t) together with a rotation psi e(i omega t) applied
to the railhead. The output comprises rail displacements and forces,
contact creepages and forces, and frictional energy dissipation. Accor
ding to the Frederick-Valdivia hypothesis, if this last quantity has a
component in phase with the input ripple, the amplitude of the ripple
will be attenuated, and vice versa. Over most of the frequency range,
a purr displacement input (psi = 0) was found to give rise, predomina
ntly, to a normal force at the railhead. A purely rotational input (De
lta = 0) caused a single point of contact to oscillate across the rail
head or, in the case of two-point contact, to give rise to fluctuating
out-of-phase forces at the two points. The general tenor of behaviour
revealed by the three models was similar: frictional energy dissipati
on, and hence wear, increases with conformity and is usually of such a
phase as to suppress corrugation growth. Thus the association, found
on the Vancouver mass transit system, of corrugations with the develop
ment of close conformity between wheel and rail profiles must arise fr
om some feature of the system not included in the present models.