Detection of Rail Fastener Assembly Defects Using Axle-Box Acceleration

Track roughness, irregularities and defects result in axle-box accelerations with a wide range of frequencies. In addition to track features, the axle-box acceleration is also influenced by vehicle speed, suspension parameters, track support, and axle load. Track fastener assembly failure increases track flexibility, affects axle-box acceleration, increases dynamic load factor and can deteriorate ride comfort. An onboard monitoring system is required to locate this defect and gauge its severity.

In this work, a template-based squared correlation coefficient method and continuous wavelet transform method are used to identify the track fastener assembly defect location and defect strength. The proposed methods are tested using a validated track-vehicle model as well as using experimental data. The effectiveness of the proposed methods is evaluated for different train speeds, axle loads and magnitudes of track irregularities.

Squared correlation coefficient method works well at higher speeds, higher axle loads, lower track irregularities and higher number of consecutive track fastener assembly defects. The severity of the defects is clearly evident in normalized scalogram plots.

Template matching-based squared correlation coefficient method, using axle-box acceleration for tracks with and without irregularities, can be used to identify the location of the defect(s). On the other hand, normalized continuous wavelet transform method can be used to identify the severity of defects.