Problem description and significance:
Friction control at the wheel-rail interface has been an outstanding challenge in front of the railroad engineers throughout the world. Onboard solid stick friction modifier system, simply named the stick-applicator assembly, has proved to be one of the simple and efficient ways to tackle the excessive wear and rail corrugation. Interlocking solid sticks are applied to the wheel flange and tread by means of a mechanical applicator mounted on a bracket, which is connected to the bogie. Relative sliding motion in the stick-wheel interface provokes gradual transfer of solid lubricant film to the wheel-rail interface through the wheel motion. Consequently, friction control at the wheel-rail interface could be achieved. Instability and failure of stick-applicator assembly due to stick-wheel interaction destabilize its performance. A lab-scale setup has been designed at UBC to produce consistent instability, which helps examine the behavior of the stick- applicator assembly during instability. Furthermore, full-wheel rigs at LBFoster Company are used to gain a better understanding of the dynamics of the stick-applicator assembly. Experiments revealed that lack of lateral stiffness due to the presence of clearances in the stick-applicator assembly can be one of the main factors which influence on the instability of the stick-applicator assembly. Having found the role of lateral stiffness, design modifications of the stick-applicator assembly to enhance the lateral stiffness are in progress to eliminate the instability and suppress vibration in the stick-applicator assembly. The long-term plan for this research is to have structurally robust solid stick friction control systems by optimizing the required design changes. In that regard, the findings of this research could be used to improve the stick-applicator assembly performance in the wheel-rail industry.
This project is funded by LB Foster and Natural Science and Engineering Research Council of Canada (NSERC).