| This study investigates the influence of interfacial vibrational friction between the inner walls of freight train carriages and combustible cargo on spontaneous ignition characteristics in high-temperature environments. Both theoretical and experimental analyses were conducted. Theoretically, an analytical model for heat generation induced by periodic vibrational friction was proposed. By introducing frictional heat flux as a boundary condition into the fundamental theory of thermal spontaneous ignition, a criterion for the critical condition under vibrational friction was derived. Numerical results indicate that at a constant ambient temperature, increases in vibration amplitude, frequency, and contact pressure lead to higher frictional heat generation. Consequently, the critical Damk?hler number decreases, the dimensionless central temperature rises, and the time for spontaneous ignition shortens. Experimentally, medium-density fiberboard (MDF) was used as a surrogate for combustible cargo. The results verified the theoretical predictions, confirming that vibrational friction accelerates the onset of spontaneous ignition. This study elucidates the coupling mechanism between frictional heating and spontaneous ignition during railway transportation, providing theoretical and experimental support for enhancing freight safety management in high-temperature environments. |
