Determination of the Stress State Developed within a Non-Cushioned Rail Yoke and the Prediction of the Theoretical Fatigue Life

During service, freight railroad coupling systems experience heavy loading owing to various train actions. For non-cushioned railcars, the primary tensile component utilized to transfer these forces to the draft system is the yoke. The stress state developed within a yoke was analysed using both strain gauge data and non-linear finite-element methods for both static maximal loads and pseudo-static cyclic loads accounting for the non-linear material behaviour, including plasticity and strain hardening. From the stress profile developed within a yoke, the critical locations were determined and the theoretical fatigue life was calculated using various strain life fatigue analysis methods considering both the uniaxial and biaxial stress conditions that exist. Using these data, a possible failure mode is presented.