Stress-based fatigue reliability analysis of the rail fastening spring clip under traffic loads

Nowadays, the rail fastening systems play an important role for preserving the connection between the rails and sleepers in various conditions. In this paper, stress based concept is used to develop a comprehensive approach for fatigue reliability analysis of fastening spring clip. Axle load, speed and material properties are assumed to be random variables. First, track and train models are analyzed dynamically in order to achieve displacement time history of fastening spring clip. Then this displacement time history is applied to the fastening spring clip in FE software to obtain variable amplitude of stresses. Crack nucleation life is calculated by rain-flow method and Palmgren-Miner linear damage rule. First Order Reliability Method (FORM) and Monte-Carlo simulation technique are employed for the reliability index estimations. The influences of various random variables on the probability of failure are investigated by sensitivity analysis. The results show that the equivalent stress range and material parameter have significant effect on fatigue crack nucleation.