Load spectrum extrapolation method for fatigue damage of the turnout based on kernel density estimation

The 200 km/h mixed passenger and freight railway with movable-point frog requires a comprehensive consideration of factors such as the heavy axle loads of freight trains, the high operating speeds of passenger trains, and the complex and variable wheel-rail contact in the frog areas. Components with variable cross-sections, such as the point rail, are more susceptible to fatigue damage. This study aims to propose a whole system framework for generating the load spectra of the turnout and analyzing the distribution of fatigue damage. To this end, the influence of key dynamic parameters on the time-frequency domain wheel-rail load characteristics of both freight and passenger cars was clarified. The load characteristics of the point rail under complex random operating conditions were statistically analyzed. Subsequently, extrapolating the load spectrum based on the kernel density estimation method. On this basis, analyzing the fatigue damage distribution of movable-point frog. The results indicate that the initial load-bearing region ranges from the top width of 29 mm to 44 mm for the point rail under random operating conditions. The load-bearing exhibits considerable divergence and a pronounced degree of randomness at the same top width. In comparison between passenger and freight cars, it is observed that the freight car initiates loading earlier and undergoes a more protracted wheel load transition range. The fatigue damage is mainly caused by load levels 4 to 8, and relatively significant fatigue damage occurs in the region with the top width of 40 mm to 50 mm, which is consistent with the main fatigue damage area observed in the field.