Experimental study on dynamic performance and wear law of fixed frog sections on heavy-haul lines

Abstract

This study presents a comprehensive investigation into the dynamic performance and wear characteristics of heavy-haul trains negotiating fixed frog sections. Utilizing a No.12 fixed frog as the research subject, the experimental design incorporated four distinct axle loads and two operational directions to evaluate full-scale vehicle dynamics. The research methodology involved two primary phases: initial assessment of vertical and lateral forces on unworn fixed frogs, followed by derailment coefficient and wheel load reduction rate calculations to analyze dynamic behavior under varying operational conditions. Subsequently, vertical force measurements were conducted across five progressive wear stages to establish correlations between wheel-frog interaction forces and wear progression. The experimental results reveal that maximum vertical and lateral forces on unworn fixed frogs consistently occur at the nose rail position, 0.75–1.25 m from the theoretical point. Notably, the peak vertical force exceeds 150 % of the static load, identifying this location as a critical stress concentration zone. Wear progression analysis demonstrates a non-linear relationship between vertical force and wear depth, characterized by initial rapid increase, subsequent slight decrease, and final accelerated growth. Critical wear thresholds were identified at 4 mm (initiation of stable wear) and 7 mm (transition to severe wear). Based on vertical force analysis, recommended wear limits for double-track railways are proposed: 8 mm for facing direction operations and 10 mm for trailing direction operations. These findings provide significant insights for mitigating fatigue damage and optimizing maintenance strategies for fixed frog sections in heavy-haul railway systems, ultimately contributing to enhanced operational safety and extended service life.