Abstract
The effect of two common types of short-wavelength irregularities (local imperfections and periodic short-wavelength irregularities) of the railway catenary on the pantograph–catenary interaction performance are studied and their potential identification approaches are explored in this paper. The analysis of the intrinsic mode functions of panhead acceleration indicates that the effect of local imperfection can be reflected in the high-order deformation mode of the contact wire. The cut-off frequency is suggested to cover the wavelength smaller than 1/8 of the dropper to dropper distance, which can be used to identify the local imperfection. The instantaneous energy obtained by the Hilbert transform is used to localise the local imperfection. The effect of periodic short-wavelength irregularities can be recognised as the introduction of non-Gaussian behaviour in the contact force at specific wavelengths. Thus, spectral kurtosis is utilised to identify the deviating wavelength. The short-wavelength irregularity can be localised by the time-frequency analysis of the intrinsic mode function containing the identified deviating wavelength. The examples with measurement data indicate the validation of the present methods with some improvements to the current equipment.
Highlights
The results indicated that the standard deviation of lowfrequency contact force was not significantly changed by the slight wear, which pointed out that the traditional assessment indicators might be invalid to evaluate the contribution of the short-wavelength contact wire irregularity (CWI)
To achieve the main goals, this paper presents a mathematical model of the pantograph–catenary interaction based on the absolute coordinate nodal formulation (ANCF), which has been proven to be an effective method to describe the geometrical nonlinearity in railway dynamics [39]
The application examples with measurement data indicate that present methods have the potential to be used in actual operation with some improvements in the current monitoring trains
Summary
The catenary suffers long-term impacts from the pantographs and various disturbances from environmental conditions. These factors, together with mounting imprecisions and inadequate maintenance, present the primary source of contact wire irregularity (CWI), which is the common early fault in the catenary and directly affects the interaction performance between the pantograph collector and the contact wire. The second and third ones present the main source of short-wavelength disturbance to the pantograph–catenary interaction, which directly causes hard-spot and contact loss. The effect of the short-wavelength irregularities is not distinct in the time-history of contact force or the contact wire height and challenging to be identified by the regular inspection [4]
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