Investigation on the rolling contact fatigue cracks initiation of subway fixed frogs based on transient dynamics
摘要
The issue of fatigue damage to rails has become increasingly prominent with the rise in subway traffic and speed. The hazardous space of the turnout frog significantly intensifies the dynamic interaction between the vehicle and the frog rail, leading to more pronounced fatigue damage in the turnout rail. This paper focuses on the No. 9 turnout fixed frog commonly used in subway lines. A three-dimensional explicit transient rolling contact finite element model of the fixed frog is established. The dynamic response of wheel–rail rolling contact is analyzed under various speeds and vertical stiffness conditions. Rolling contact fatigue crack locations, angles, and initiation life were investigated. The research indicates that the 30 mm top width cross-section of the nose rail is most susceptible to fatigue cracks, which initiate on the rail surface. The angle between the crack initiation surface and the lateral direction is between 70° and 95°. Higher speeds result in shorter fatigue life, while the vertical stiffness of the fastener has less of an effect. The simulation results align with findings from field surveys. The established model and research conclusions can provide theoretical support for optimizing fixed frog structures and predicting fatigue life.