Wheel-rail dynamic interaction induced by tread spalling integrating with pre-fatigue damage of materials

Tread spalling is a typical damage type of wheel tread of railway vehicles, which produces severe wheel-rail dynamic interaction, further aggravating the deterioration of crucial components of vehicle and track, especially for coupling with fatigue damage of wheel/rail materials generated in the long-term operation. In this study, a comprehensive three-dimensional (3-D) wheel-rail transient contact finite element model was constructed, to investigate wheel-rail dynamic interaction by tread spalling, where dynamic mechanical properties of wheel-rail material under different equivalent service cycles were considered. The time- and frequency-domain responses of wheel-rail contact forces, wheel-rail adhesion-slip distribution and stress states during wheel rolling over tread spalling region were examined, and the wheel-rail plastic deformation and wear damage were also predicted. Influences of pre-fatigue damage (PFD) and strain rate effect (SRE) of materials on wheel-rail dynamic interactions were highlighted, in terms of the effects of train speed, spalling length and spalling depth. The results indicate that wheel-rail forces and stress are greatly raised as the wheel rolls over spalling region, resulting in large plastic strain and wear damage on the wheel and rail. The SRE significantly inhibits plastic deformation and exacerbates wear of the wheel and rail, while PFD increases plastic deformation but mitigates wear damage to the wheel-rail system. The train speed and spalling length both have a notable effect on plastic strain and wear damage of wheel and rail, while spalling depth only has an obvious influence on the wheel. The detailed modelling and obtained results are beneficial for spalling identification in dynamic detection and reasonable maintenance of wheel-rail system.