In Chinese metro lines, rail corrugation on both tangential and tight curved tracks with Cologne-egg type fasteners is very severe. Based on the viewpoint of friction-induced vibration causing rail corrugation, the rail corrugation on a tangential track with Cologne-egg type fasteners is studied in this paper. A vibration model of an elastic multiple-wheelset-track system with Cologne-egg type fasteners is established. Both the complex eigenvalue analysis and the transient dynamic analysis are performed to study the stability and the dynamic performance of the wheelset-track system. The simulation results show that a low rail support stiffness value is responsible for rail corrugation on the tangential track. When the Cologne-egg fasteners characterised by a lower stiffness value are replaced with the DTVI2 fasteners characterised by a higher stiffness value, rail corrugation disappears. However, rail corrugation on tight curved tracks cannot be suppressed using the same replacement. The above conclusions are consistent with the corrugation occurrences in actual metro tracks.

The purpose of the present paper is to investigate the correlation between the friction-induced oscillation of a wheelset-track system and curve radius and to explain a general phenomenon of rail corrugation based on the viewpoint of friction-induced oscillation. The typical phenomenon of rail corrugation in metros is that corrugation generally arises when the curve radius is quite small, whereas it rarely occurs when the curve radius is larger or on a straight track. Different multi-body models of the vehicle-track system and finite element models of the multiple-wheelset-track system with different curve radii are established respectively. According to the creep force analyses and unstable vibration analyses, the correlation between the creep force and friction-induced oscillation can be identified. Then, the effect of the track curve radius on the friction-induced oscillation of the wheelset-track system can be summarized, which provides an explanation of the typical phenomenon of corrugation.

In this work, an experimental and numerical study is performed to understand squeal generation and suppression of a pad-on-disk friction system. Several friction material specimens having various orientation degrees of grooves cut on their surfaces are tested. Numerical studies using the methods of complex eigenvalue analysis and dynamic transient analysis are conducted to simulate the experimental process with the finite element (FE) software abaqus. Both experimental and numerical results show that surface modifications of friction material specimens have a significant influence on the squeal instability: cutting a 45 deg or 90 deg groove on the material surface can significantly reduce squeal noise, cutting a 135 deg groove just reduces squeal noise moderately and cutting a 0 deg groove cannot reduce squeal noise. Moreover, the contact pressure distributions for the original surface and modified surfaces are studied to provide a physical explanation of the noise phenomenon. The major finding that friction-induced noise can be reduced by means of suitable structural modifications of the contact interface is expected to have important and much wider applications.

To study the evolution of the pantograph-catenary system dynamic under crosswind environments, this paper examines the effect of crosswind on the quality of the current collection and explores the wind stability of different longitudinal suspension forms of the catenary system. Firstly, the catenary with different longitudinal suspension forms is established based on the absolute node coordinate formulation, and the initial equilibrium configuration are accurately obtained. Secondly, the pantograph model is derived, and the pantograph-catenary system coupling model is established according to the standard EN 50318:2018 and passed the verification. Then, the random wind speed spectrum of the simulated environment is built based on the Davenport spectrum and is validated. Finally, the pantograph-catenary system dynamic behavior under the crosswind environments is simulated. The results show that the crosswind affects the low-frequency vibration part of the pantograph-catenary system, with the increase in wind speed and the standard deviation of contact force, the worse current collection quality. Different longitudinal suspension forms of catenary systems have various wind stability. Semi-inclined and inclined longitudinal suspension forms have better wind stability, and the maximum reduction of contact force standard deviation is 14.05%, which can effectively improve the current collection quality in crosswind environments.

This paper studied a special rail corrugation phenomenon occurring at a braking section of Shenzhen metro 3 line based on friction-excited oscillation. The rail corrugation is strongly related to braking operation, when the braking operation is cancelled, the corrugation did not appear again after being grinded. In this paper, a new viewpoint that the corrugation originates from the unstable vibration of the wheel-rail-brake shoe braking system is put forward. To test this point of view, a finite element model composed of two wheelsets with brake shoe braking system and two rails for complex modal analysis is established. Parameter sensitivity analysis is carried out to develop some measures to suppress rail corrugation. The results show: rail corrugation at the long downhill braking section originates from the unstable vibration at about 430 Hz of the wheel-rail-brake shoe braking system. The corrugation wavelength predicted by the finite model is about 55 mm, which shows good agreement with the on-site data. The results of parameter sensitivity analysis show: the influence of the coverage angle of brake shoe on the rail corrugation is significant. The possibility of the rail corrugation and its progression speed increase significantly with the decrease of the coverage angle of the brake shoe. To suppress the rail corrugation, the coverage angle should not be less than 48° when designing the brake shoe structure. The influence of the installation position of brake shoe on the rail corrugation is also obvious. The position of brake shoe with pressure angle of 8° can restrain rail corrugation to the greatest extent. The contact state between brake shoe and wheel tread has little influence on rail corrugation. In practice, the brake shoe should be in full contact with the tread as far as possible.

This paper studies the effect of wheel polygonalization and material properties on the fatigue failure of fastener clips in high-speed railway lines and puts forward the corresponding inhibition measures. Vibration frequencies excited by 24th-order wheel out-of-roundness (OOR) were analysed by on-site tests of the axle box vertical vibration acceleration. A finite element modelling method of polygon-shaped wheels was proposed, which was verified by comparing the field measurement with the dynamic simulation. The dynamic response of the fastener clip was simulated by using a rigid–flexible coupled model of the wheelset-track system. The effect of amplitudes as well as typical wavelengths of wheel OOR on the fracture of the clip was analysed based on the Miner fatigue damage accumulation ruler. The results show that when the wheelset ran at 237 km/h on the track, the 24th-order wheel OOR had no obvious effect on the Mises equivalent stress of the clip. When the amplitude of the 24th-order wheel OOR reached 0.225 mm and above, excited vibrations of about 1172 Hz were transmitted from the wheelset-rail system to the fastener systems, thus reducing the safe operating life of the clips. This phenomenon can be inhibited by setting a reasonable amplitude threshold for wheel re-profiling. Wheel eccentric wear (first-order OOR) and 12th-order OOR had lesser effects on the fatigue failure of the clip. The decrease of Poisson’s ratio or the increase of Young’s modulus of the material could cause the maximum Mises equivalent stress at the clip to increase, which might induce cracks, thus leading to the fracture of the clip. Therefore, during the production process, the Poisson’s ratio and Young’s modulus of fastener clips should be strictly controlled to ensure that they are within the permitted range.