Vertical dissipation characteristics of a vehicle–road coupled half-car system under plateau freeze–thaw conditions

Freeze–thaw degradation alters tire–road contact and upper-subgrade support, but its effect on vehicle-side vertical energy dissipation remains unclear. This study develops a six-coordinate coupled half-car–road-support model that separates effective tire–road contact stiffness from the deformable road boundary and partitions suspension, tire and road-support dissipation. The conventional four-coordinate subsystem is compared with an external benchmark, while the environmental mapping and complete formulation are assessed through literature consistency, rigid-road limits, energy-balance closure and numerical convergence. These checks assess internal consistency rather than field validity. The benchmark gives a 5.86% mean absolute percentage error and a correlation coefficient of 0.991; modulus-comparison, rigid-road and energy-balance errors are 7.67%, below 0.003% and below 0.37%, respectively. Controlled grade-C cases show that the combined − 4.55% change in E v /L reflects opposing temperature (+ 2.00%), moisture (− 0.866%) and freeze–thaw-cycle (− 6.162%) effects. Paired uncertainty propagation yields negative changes in all 1000 samples, with a median of − 5.015% and a central 95% range of − 8.319% to − 2.672%. Total modeled dissipation changes by only 0.20% because road-support dissipation increases. Tire stiffness and damping have the largest absolute PRCC associations within the prescribed domain. The results describe model-predicted energy-path redistribution rather than field-validated vehicle behavior or direct fuel, emission or ride-comfort effects.