The ladder track used by the Beijing subway which can be subjected to rail corrugation is considered in this paper. Dynamic models of the vehicle and the ladder track are developed to analyse the track vibration behaviour. Using these models the effect of the most significant ladder track parameters on track vibrations are analysed in the frequency and time domains. Using experimental and numerical results the vibration frequency of the rail that is responsible for rail corrugation is determined. Based on the results of the parametric study, an optimisation of the mechanical properties of the ladder track to reduce or eliminate the track vibrations at the corrugation frequency and ultimately to reduce the chance of rail corrugation is performed using a genetic algorithm-based approach. The results of the optimisation are presented and discussed.

The combination model of the vehicle and ladder track system that accounts for the wheel–rail interface has been developed to analyze the wheelset and ladder track vibration characteristics in the frequency and time domains. In the wheel–rail interface, the vertical contact is represented by contact stiffness derived from the Hertz theory of normal elastic contact, and lateral contact is idealized by linear contact used Kalker linear rolling contact theory. The considerable noise and vibration frequency of the ladder track is determined by experimental investigation results. Then the effect of the most significant ladder track parameters on the track vibration is analyzed in time domain using the vehicle–track coupling model. Based on the results of the parametric study, an optimization of the mechanical properties of the ladder track to reduce the track vibrations is performed using the multipoint approximation method. The results of the optimization are presented and discussed.

It is usually difficult to obtain the modal characteristics of the rail fastening clip analytically owing to its complex spatial structure and operating environments. Therefore, experimental modal testing is frequently adopted to identify the modal characteristics of rail fastening clips. This study takes the SKL 15 clip of the Vossloh 300-1 fastening system as the research object to analyse the following three aspects in great detail: (1) Locations of the measurement points are reasonably designed to capture all modes of the clip in the frequency range 0–1000 Hz. (2) The appropriate sensors are selected for the clip in different operating situations by comparing the measured results of three kinds of sensors, namely the accelerometer, laser vibrometer and sound pressure sensor. In addition, the test results suggest that the accelerometer which has a strong anti-disturbance ability in an ambient environment is recommended to be chosen in a noisy environment while the laser vibrometer and sound pressure sensor which have no added mass to the tested structures may be used in an indoor environment with suitable temperature and low noise. (3) In order to eliminate the effect of the additional mass on the modal characteristics of the clip, the accelerometer is recommended to be installed at the rear end of the side leg of the clips in the experimental modal test.

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