Aobo Yang

Ice accretion and wind-induced galloping of auxiliary conductors threaten the operational reliability of electrified railway overhead contact systems. This study develops an integrated numerical framework for simulating ice-shape evolution and galloping responses of a 20.6-mm-diameter auxiliary conductor. Airflow and supercooled droplet trajectories are calculated using the SST k–ω model and the Lagrangian discrete-phase method, respectively. The Makkonen icing theory and Messinger heat-balance model are coupled to predict droplet collection, freezing, and ice growth. The effects of wind speed, droplet median volume diameter, liquid water content, and ambient temperature on ice morphology are investigated. A two-dimensional, two-degree-of-freedom fluid–structure interaction model is further established using an overset mesh and user-defined functions and validated through low-speed wind-tunnel tests. Results show that ice initially forms at the windward leading edge and extends toward both sides. Wind speed increases ice thickness and coverage, droplet size mainly enlarges the icing region, liquid water content promotes ice growth, and lower temperature concentrates ice on the windward surface. Unlike the decaying response of the bare conductor, the crescent-iced conductor exhibits sustained periodic galloping with amplitudes increasing markedly with wind speed. The proposed framework supports icing-risk assessment and anti-galloping design.

This study investigates the wind-induced vibration of railway overhead contact line additional conductors and the service safety of fittings in high-altitude canyon environments. Using the Dadu River canyon railway corridor as the engineering background, a three-dimensional stochastic wind field with temporal and spatial correlations is generated by combining the Kaimal, Tieleman and Panofsky spectra with a fourth-order autoregressive model. Wind-speed histories are converted into wind loads using quasi-steady aerodynamic theory. A geometrically nonlinear model based on the absolute nodal coordinate formulation is established, with suspension and support fittings represented by a swingable rod element and three-directional equivalent stiffness, respectively. Time-domain, rainflow-counting, power-spectral and parameter-sensitivity analyses are performed. Results show that fitting type strongly affects conductor-end response but has limited influence on mid-span vibration. Suspension fittings release wind-induced deformation through swinging, reducing stress peaks and high-amplitude cycles, whereas support fittings restrain end displacement but increase local constraint reactions and fatigue risk. The findings support fitting selection and wind-resistant fatigue design for additional conductors in canyon railway overhead contact lines.

The galloping behavior of ice-covered additional overhead contact line conductors in a high-wind environments presents a significant threat to the safe operation of electrified railways. This study investigates the galloping phenomenon of additional conductors under ice accumulation conditions, establishing a nonlinear finite element model. By integrating aerodynamic characteristics, the vibration patterns and influencing factors of the galloping behavior are systematically explored. First, aerodynamic parameters for various ice cover shapes, ice thicknesses and wind speeds are simulated using the FLUENT fluid dynamics software. The instability of the ice-covered additional conductors is evaluated using the Den Hartog coefficient criterion, and the accuracy of the simulation is validated through wind tunnel experiments, providing a foundation for galloping prediction. Next, a nonlinear finite element model of the ice-covered additional conductor is developed, and numerical simulations are carried out using the Newmark-[ ] method to replicate the galloping behavior. The formation and motion characteristics of the conductor’s vibration are thoroughly analyzed. Finally, the effect of the conductor’s structural parameters on galloping behavior is investigated. By varying parameters such as tension, span distance and the number of spans, their influence on the galloping response is examined. The results indicate that higher ice thickness, increased wind speed, and an optimal range of attack angles contribute to a greater susceptibility to galloping. The galloping behavior of ice-covered additional conductors is a gradual process, primarily characterized by vertical vibration, supplemented by horizontal oscillations, forming an elliptical trajectory. Furthermore, increasing the tension, reducing the span, and optimizing the number of spans help mitigate the galloping behavior. This study provides a theoretical foundation for the prevention and control of galloping in ice-covered additional conductors and offers valuable guidance for the design and maintenance of electrified railways.

Wind-induced vibrations in additional conductors on electrified railway catenary systems pose a risk to operational safety and long-term structural performance. This study investigates the dynamic response of these components under wind excitation through nonlinear finite element analysis. A wind speed spectrum model is developed using wind tunnel tests and field data, and the autoregressive method is used to generate realistic wind fields incorporating longitudinal, lateral, and vertical components. A detailed finite element model of the additional conductors and fittings was constructed using the Absolute Nodal Coordinate Formulation to account for large deformations. Time domain simulations with the Newmark-β method were conducted to analyze vibration responses. The results show that increased wind speeds lead to greater vibration amplitudes, and the stochastic nature of wind histories significantly affects vibration modes. Higher conductor tension effectively reduces vibrations, while longer spans increase flexibility and susceptibility to oscillation. The type of fitting also influences system stability; support-type fittings demonstrate lower stress fluctuations, reducing the likelihood of resonance. This study enhances understanding of wind-induced responses in additional conductor systems and informs strategies for vibration mitigation in high-speed railway infrastructure.