Loading and resulting damages in turnout & improvement

January 11, 2016 in

PhD Research by Zilong Wei


Advisor(s)
Rolf Dollevoet, Zili Li

Period
02/01/2012 - ongoing

Theme(s)


Keywords
contact mechanics, railway structures, railway turnouts,

Funding
China Scholarship Council, TU Delft

Link or Download
Not available

Summary

Turnout is one of the most critical components in the railway infrastructure because of its multiple functions in guiding trains, supporting the load, providing traction/braking, being part of the electrical circuit for signalling and route for return current of power supply. Because of geometric discontinuities and stiffness irregularities such as the gap between wing and nose rails, dynamic Wheel/Rail interaction is more complex in railway turnouts than that in ordinary tracks. Turnout life is predominantly determined by rolling contact fatigue, plastic deformation and wear. These damages are of paramount importance for the maintenance and safeguarding of railway system. Though solutions such as movable frog turnout have been implemented to minimize the damages caused by dynamic forces, new turnout system including structure, material and maintenance method is still needed to improve defect resistance and decrease the maintenance operation. The research is expected to open up possibilities for production of a new generation of turnout with much improved defect resistance. The implementation of the new turnouts should decrease the maintenance operation greatly in comparison to the current situation. Considering the energy saving coming from increased turnout life and decrease in maintenance a significant reduction in CO2-emission should also be foreseen in the positive effects of the research. The mechanical and tribological aspects of defect appearance are recently reported and these studies provide an excellent basis for further understanding of the loading and contact conditions leading to damage development. In this project damaged turnout samples will be collected from fields, particularly from monitored sites. The loading and damage histories of these samples are known. The samples cover a broad range of loading conditions and all the stages of damage initiation and growth. State-of-the-art mathematical models will be used and further developed to systematically establish relationships between mechanical loading conditions and damage evolution. By comparing with laboratory tests and field tests, the relationships between loading conditions, materials properties and damage development are identified, thus significantly enlarging the applicability of numerical simulation for newly designed rails and materials.