Performance and safety evaluation of rack vehicle in mountainous regions under pulsating wind loads

The operational stability and safety of rack vehicles are critically impacted by the pronounced non-stationarity of pulsating crosswinds in mountainous terrain, potentially leading to derailment. To address this issue, the coupling mechanisms among terrain, wind field, and vehicle system were systematically investigated. A comprehensive rack vehicle–track dynamic model was established, integrating vehicle–track coupling dynamics, gear dynamics, and stochastic analysis, with considerations for nonlinear wheel–rail and gear–rack contact interactions. Terrain-induced wind speed amplification was considered, and pulsating crosswinds exhibiting spatial lateral and vertical correlations were synthesized using harmonic methods and applied as stochastic excitations. A stochastic framework capturing the triple coupling effects was thereby developed to analyze the system's dynamic responses. The dynamic responses of rack vehicles under varying gradients have been analyzed, and wind speed thresholds for safe operation have been proposed. It has been found that the operational stability of rack vehicles is significantly impaired by pulsating crosswinds, and safety is directly threatened under severe conditions. Lateral gear misalignment is induced by pulsating crosswinds, the meshing contact area is reduced, and the dynamic engagement between gear and rack is degraded. Furthermore, the intensity of pulsating crosswinds is increased with gradient, markedly reducing the lateral stability of rack vehicles. At gradients of 100‰, 150‰, and 200‰, wheel unloading rates exceeding the safety threshold are caused by wind speeds at standard height of 29, 24.5, and 22.5 m·s−1, respectively.