Numerical modeling of wheel-rail squeal-exciting contact

Abstract

Complex frictional rolling contact and high-frequency wheel dynamic behavior make modeling squeal greatly challenging. The falling-friction effect and wheel mode-coupling behavior are believed to be the two main mechanisms that generate unstable wheel vibration and the resulting squeal noise. To rigorously consider both mechanisms in one model, we propose an explicit finite element (FE) model to simulate wheel-rail dynamic frictional rolling. Wheel-rail squeal-exciting contact is investigated with considerations of dynamic effects, unsteady lateral creepage and velocity-dependent friction. With the inclusion of the dynamic effects in the contact solution, large-creepage-induced waves, which share features with Rayleigh waves, are discovered. The solutions of the dynamic contact calculated using the proposed model indicate that the explicit FE method is able to reproduce the falling-friction effect. The transient analyses of wheel-rail frictional rolling with wheel lateral creepage show the coupling of the axial and radial dynamics of the rolling wheel model, suggesting that the explicit FE method can also reproduce the mode-coupling behavior. This study improves the understanding and modeling of squealexciting contact from the perspective of wheel-rail dynamic interaction.

A numerical study on waves induced by wheel-rail contact

“…The possible link between the generation of perturbation-induced waves and the stickslip contact behaviour is then discussed. After that, the study analyses the physical characteristics of the creepage-induced wave observed in [19] , confirming that the simulated wave is a Rayleigh wave. Although the Rayleigh wave has been extensively proposed to enable detection of the presence of rail cracking [22,23] .…”

“…Fig. 2 (a) shows a creepage-induced wave pattern calculated with the explicit FE squealexciting contact model presented in [19] , in which the wheel-rail rolling contact with a large lateral motion of the wheel is simulated; Fig. 2 (b) shows another creepage-induced wave pattern observed in the simulation of the wheel-rail two-point contact transition [18] , in which large creepage occurs at the first contact patch on the rail top when the rolling wheel negotiates with the rail via flange contact.…”

“…The perturbation initiates close to the leading edge of the contact patch in [29] and at the juncture of the adhesion-slip regions in [30] . The animations were obtained by explicit FE simulation of wheel-rail frictional rolling contact without wheel lateral motion (simulation case 1 in [19] ).…”

“…The explicit FEM has since been increasingly employed for the simulation of wheel-rail dynamic contact involving, for example, impact [6][7][8][9][10][11][12][13][14][15] , flanging [16][17][18] and friction-induced instability [19] . The overall picture of the contact-induced wave pattern was observed when the authors of this paper simulated the non-steady-state transition of wheel-rail contact from a single point to two points [18] .…”

“…The wave was found to be initiated next to the juncture of the adhesion and slip regions in the contact patch, where the maximum surface shear stress is located. After this study, the waves generated by the impacts at an insulated rail joint [11] and a crossing [13] and the waves caused by wheel-rail lateral creepage [19] were reproduced with explicit FE contact models. The explicit integration algorithm is considered to be computationally attractive and naturally suitable for analysing the contact-induced wave propagation because the total dynamic response time that must be modelled is only a few orders of magnitude longer than the stability critical time step [20] and the contact conditions are updated within a small time interval, which facilitates the analysis of high-frequency wave propagation [21] .…”