Condition identification and vibration response of high-speed railway catenary steady arms under abnormal service conditions

Abstract

Abnormal wear of catenary steady arms represents a typical concealed defect that threatens the safe operation of high-speed railway pantograph-catenary systems. The essence of this defect lies in the cumulative abnormal vibration and progressive contact damage induced by service degradation of the steady arm. In this study, the traditional hook-ring steady arm was taken as the research object. Based on the mechanical characteristics of steady arm and the corresponding geometric features in dynamically measured stagger values, two typical service conditions were defined: axially tensioned (normal) and axially slackened (abnormal). A pantograph-catenary coupled dynamic simulation model was established, and a non-intrusive ground-based vibration acquisition system based on computer vision was deployed to capture the dynamic responses of steady arms under various operational conditions. Time-domain and FFT-based frequency-domain analyses revealed that, compared with the normal conditions, the vertical vibration peak values and root-mean-square values of steady arms under abnormal service conditions increased significantly, and the dominant frequency shifted toward lower values. Furthermore, the full width at half maximum and the post-peak oscillation envelope time constant of measured signals were generally elevated under abnormal conditions.The findings elucidate the dynamic evolution mechanism underlying reduced constraint stiffness and impeded energy dissipation in the abnormal service conditions, providing theoretical basis and data support for early identification and condition assessment of concealed defects in high-speed railway catenary systems.